Annotated Example SDP for WebRTC

Internet-Draft	SDP4WebRTC	December 2020
Nandakumar & Jennings	Expires 20 June 2021	[Page]

Abstract

The Web Real Time Communications (WebRTC) family of protocols defines mechanism for direct interactive rich communication using audio, video, and data between two peers' web browsers. With in the WebRTC framework, the Session Description Protocol (SDP) is used for negotiating session capabilities between the peers. Such a negotiation happens based on the SDP offer/answer exchange mechanism¶

This document provides an informational reference in describing the role of SDP and the offer/answer exchange mechanism for the most common WebRTC use cases.¶

This document makes no changes to the SDP offer/answer exchange mechanism.¶

5. WebRTC Session Description Examples

A typical web-based real-time multimedia communication session can be characterized as follows:¶

It has zero or more audio-only, video-only or audio/video RTP sessions,¶
may contain zero or more non-media data sessions,¶
All the sessions are secured with DTLS-SRTP,¶
Supports NAT traversal using the ICE mechanism,¶
Provides RTCP-based feedback mechanisms,¶
Sessions can be over IPv4-only or IPv6-only or dual-stack based clients,¶
Supports BUNDLE-based grouping of media streams over a single 5-tuple transport.¶

5.1. Some Conventions

The examples given in this document follow the conventions listed below:¶

In all the examples, Alice and Bob are assumed to be the WebRTC peers.¶
It is assumed that for most of the examples, the support for [I-D.ietf-mmusic-sdp-bundle-negotiation] is established a priori either out-of-band or as a consequence of a successful offer/answer negotiation between Alice and Bob, unless explicitly stated otherwise.¶
Call-flow diagrams that accompany the use cases capture only the prominent aspects of the system behavior and intentionally are not detailed, to improve readability.¶
Even though the call-flow diagrams show SDP being exchanged between the parties, it doesn't represent the only way an WebRTC setup is expected to work. Other approaches may involve WebRTC applications to exchange the media setup information via non-SDP mechanisms as long as they conform to the [I-D.ietf-rtcweb-jsep] API specification.¶
The SDP examples deviate from actual on-the-wire SDP notation in several ways. This is done to facilitate readability and to conform to the restrictions imposed by the RFC formatting rules.¶
- Visual markers/Empty lines in any SDP example are inserted to make functional divisions in the SDP clearer, and are not actually part of the SDP syntax.¶
- Excepting the above two conventions, line endings are to be interpreted as <CR><LF> pairs (that is, a US-ASCII 13 followed by a US-ASCII 10).¶
Against each SDP line, pointers to the appropriate RFCs are provided for further informational reference. Also an attempt has been made to provide explanatory notes to enable better understanding of the SDP usage, wherever appropriate.¶
The following SDP details are common across all the use cases defined in this document unless mentioned otherwise.¶
- DTLS fingerprint for SRTP (a=fingerprint)¶
- RTP/RTCP Multiplexing (a=rtcp-mux)¶
- RTCP Feedback support (a=rtcp-fb)¶
- Host and server-reflexive candidate lines (a=candidate)¶
- DTLS-SRTP Setup framework parameters (a=setup)¶
- RTCP attribute (a=rtcp)¶
- RTP header extension indicating audio-levels from client to the mixer¶
For specific details, readers must refer to the [I-D.ietf-rtcweb-jsep] specification.¶
The term "session" is used rather loosely in this document to refer to either a "communication session" or an "RTP session" or a "RTP stream" depending on the context.¶
Payload type 109 is usually used for OPUS, 0 for PCMU, 8 for PCMA, 99 for H.264, and 120 for VP8 in most of the examples to maintain uniformity.¶
The IP Address:Port combinations '192.0.2.4:61665' (host) and '203.0.113.141:54609' (Server Reflexive) are typically used for Alice.¶
The IP Address:Port combinations '198.51.100.7:51556' (host) and '203.0.113.77:49203' (Server Reflexive) are typically used for Bob.¶
The IPv6 addresses 2001:db8:8101:3a55:4858:a2a9:22ff:99b9 and 2001:db8:30c:1266:5916:3779:22f6:77f7 are used to represent Alice and Bob's host addresses respectively.¶
In actual use the values that represent SSRCs, ICE candidate foundations, WebRTC MediaStream, and MediaStreamTrack IDs values shall be much larger than and/or random in comparison to the ones shown in the examples.¶
tls-id attribute values 89J2LRATQ3ULA24G9AHWVR31VJWSLB68 and UKA29UQLTF69OJW4WNPNUO2Y0GF1FJOZ are used for Alice. The values CJ6FF9ZZMJW7MDRJIR7XVIQM48GE1G31 and 9AIFS8AQ009IXF5D6QQUJ7P8BXPEZJ8G are used for Bob.¶
identity attribute values are split across multiple lines to enhance readability, thus any line breaks and indentations in the value must be ignored.¶
SDP attributes in the examples closely follow the checklist defined in Appendix A.1.¶

5.2. Basic Examples

5.2.1. Audio Only Session

This common scenario shows the SDP for a secure two-way audio session with Alice offering Opus, PCMU, PCMA and Bob accepting all the offered audio codecs.¶

This example also shows the endpoints being [RFC8445] compliant by including "ice2" ice-options attribute.¶

        Two-way Audio Only Session

Alice                                Bob
|                                     |
|                                     |
|    offer(Audio:Opus,PCMU,PCMA)      |
|------------------------------------>|
|                                     |
|                                     |
|   answer(Audio:Opus,PCMU,PCMA)      |
|<------------------------------------|
|                                     |
|                                     |
|Two-way Opus Audio (preferred-codec) |
|.....................................|
|                                     |
|                                     |

Table 1: 5.2.1 SDP Offer
Offer SDP Contents	RFC#/Notes
v=0	[RFC4566]
o=- 20518 0 IN IP4 0.0.0.0	[RFC4566] - Session Origin Information
s=-	[RFC4566]
t=0 0	[RFC4566]
a=group:BUNDLE audio	[I-D.ietf-mmusic-sdp-bundle-negotiation]
a=ice-options:trickle	[I-D.ietf-mmusic-trickle-ice]
a=ice-options:ice2	[RFC8445]
a=identity:eyJpZHAiOnsiZG9tYWluIjoibmlpZi5odSIsInByb3RvY29sIjoiaWRwLmh0bWwifSwiYXNzZXJ0a W9uIjoiZXlKaGJHY2lPaUpTVXpJMU5pSXNJblI1Y0NJNklrcFhVeUo5LmV5SmpiMjUwWlc1MGN5STZleUptYVc1b lpYSndjbWx1ZENJNlczc2lZV3huYjNKcGRHaHRJam9pYzJoaExUSTFOaUlzSW1ScFoyVnpkQ0k2SWprek9rTXdPa kl6T2pKR09rRXlPakF3T2pBd09qQkVPalV4T2tGRE9rUXlPalUwT2pZMU9rWTBPak5DT2pkRU9qa3lPa1JET2pnN E9qTXpPalV4T2pJek9qUXdPamN5T2preE9qZ3pPalZDT2pBeE9qSkdPalV3T2pjNE9qTkdJbjFkZlN3aWFXUmxib lJwZEhraU9pSnRhWE5wUUc1cGFXWXVhSFVpZlEuSTVQdGhKNFFDT05TOFVXd25OOUh3MEdaTDl3d0RBVGRrTWtFW llmdlNVTTJ6Umd5R09WSGgzRmpnc2FPZklkRnFsNUx6azBFbndVOTNQOUlCQ0xZOWtia3V1c0V1S25YRGVNLTNIN WFmdTJvZl9CTlZjUnB3MmdBdlNBbVR6SlltcEpqMFEtdmV0TmtVT1huZE9HLUIzT3ZGb3QwZVNENlZSNUdhb2wyc GduS3FSTktOd3dacEZ1eUZZbFRodHJIdGNiT19WV3o4QnZpTThKS25OdExWd1JxNUhMX2ZLTlRCNzFDYkoyWmh5W XU1UEdwWDhXcXJMWC1ybm5YSFY3RnhoTTh5OHdrLWd5cnRZazVnbFlZeUFrcTVqZklSXzRzWER5d19Qc1BWTW1aZ XltenVGV3BQTzVFWlJYR0ZpRjFET0o4Q0Q3Z3Zta2dUdlBXSWpkemtBIn0=	Section 7.4 of [I-D.ietf-rtcweb-security-arch]
**** Audio m=line *******	*****************************
m=audio 54609 UDP/TLS/RTP/SAVPF 109 0 8	[RFC4566]
c=IN IP4 203.0.113.141	[RFC4566]
a=mid:audio	[RFC5888]
a=msid:ma ta	Identifies MediaStream ID (ma) and MediaStreamTrack ID (ta)
a=sendrecv	[RFC3264] - Alice can send and recv audio
a=rtpmap:109 opus/48000/2	[RFC7587] - Opus Codec 48 kHz, 2 channels
a=rtpmap:0 PCMU/8000	[RFC3551] PCMU Audio Codec
a=rtpmap:8 PCMA/8000	[RFC3551] PCMA Audio Codec
a=maxptime:120	[RFC4566]
a=ice-ufrag:074c6550	[I-D.ietf-mmusic-ice-sip-sdp] - ICE user fragment
a=ice-pwd:a28a397a4c3f31747d1ee3474af08a068	[I-D.ietf-mmusic-ice-sip-sdp] - ICE password
a=fingerprint:sha-256 19:E2:1C:3B:4B:9F:81:E6:B8:5C:F4:A5:A8:D8:73:04:BB:05:2F:70:9F:04:A9:0E:05:E9:26:33:E8:70:88:A2	[RFC8122] - DTLS Fingerprint for SRTP
a=setup:actpass	[RFC5763] - Alice can act as DTLS client or server
a=tls-id:89J2LRATQ3ULA24G9AHWVR31VJWSLB68	[I-D.ietf-mmusic-dtls-sdp]
a=rtcp-mux	[RFC5761] - Alice can perform RTP/RTCP Muxing
a=rtcp:60065 IN IP4 203.0.113.141	[RFC3605]
a=rtcp-rsize	[RFC5506] - Alice intends to use reduced size RTCP for this session
a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-level	[RFC6464] Alice supports RTP header extension to indicate audio levels
a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid	[I-D.ietf-mmusic-sdp-bundle-negotiation]
a=candidate:0 1 UDP 2122194687 192.0.2.4 61665 typ host	[I-D.ietf-mmusic-ice-sip-sdp] - RTP Host Candidate
a=candidate:1 1 UDP 1685987071 203.0.113.141 54609 typ srflx raddr 192.0.2.4 rport 61665	[I-D.ietf-mmusic-ice-sip-sdp] - RTP Server Reflexive ICE Candidate
a=candidate:0 2 UDP 2122194687 192.0.2.4 61667 typ host	[I-D.ietf-mmusic-ice-sip-sdp] - RTCP Host Candidate
a=candidate:1 2 UDP 1685987071 203.0.113.141 60065 typ srflx raddr 192.0.2.4 rport 61667	[I-D.ietf-mmusic-ice-sip-sdp] - RTCP Server Reflexive ICE Candidate
a=end-of-candidates	[I-D.ietf-mmusic-trickle-ice]

Table 2: 5.2.1 SDP Answer
Answer SDP Contents	RFC#/Notes
v=0	[RFC4566]
o=- 16833 0 IN IP4 0.0.0.0	[RFC4566] - Session Origin Information
s=-	[RFC4566]
t=0 0	[RFC4566]
a=group:BUNDLE audio	[I-D.ietf-mmusic-sdp-bundle-negotiation]
a=ice-options:trickle	[I-D.ietf-mmusic-trickle-ice]
a=ice-options:ice2	[RFC8445]
a=identity:ew0KICAiaWRwIjp7DQogICAgImRvbWFpbiI6ICJjaXNjb3NwYXJrLmNvbSIsDQogICAg InByb3RvY29sIjogImRlZmF1bHQiDQogIH0sDQogICJhc3NlcnRpb24iOiAibEp3WkVocmFVOXBTblJo V0U1d1VVYzFjR0ZYV1hWaFNGVnBabEV1U1RWUWRHaEtORkZEVDA1VE9GVlhkMjVPT1VoM01FZGFURGwz ZDBSQlZHUnJUV3RGVw0KICAgICAgICAgICAgICBsbG1kbE5WVFRKNlVtZDVSMDlXU0dnelJtcG5jMkZQ Wmtsa1JuRnNOVXg2YXpCRmJuZFZPVE5RT1VsQ1EweFpPV3RpYTNWMWMwVjFTMjVZUkdWTkxUTklODQog ICAgICAgICAgICAgIFdGbWRUSnZabDlDVGxaalVuQjNNbWRCZGxOQmJWUjZTbGx0Y0VwcU1GRXRkbVYw VG10VlQxaHVaRTlITFVJelQzWkdiM1F3WlZORU5sWlNOVWRoYjJ3eWMNCiAgICAgICAgICAgICAgR2R1 UzNGU1RrdE9kM2RhY0VaMWVVWlpiRlJvZEhKSWRHTmlUMTlXVjNvNFFuWnBUVGhLUzI1T2RFeFdkMUp4 TlVoTVgyWkxUbFJDTnpGRFlrb3lXbWg1VyINCn0=	Section 7.4 of [I-D.ietf-rtcweb-security-arch]
**** Audio m=line *******	*****************************
m=audio 49203 UDP/TLS/RTP/SAVPF 109 0 8	[RFC4566]
c=IN IP4 203.0.113.77	[RFC4566]
a=mid:audio	[RFC5888]
a=msid:ma ta	[I-D.ietf-mmusic-msid] Identifies MediaStream ID (ma) and MediaStreamTrack ID (ta)
a=sendrecv	[RFC3264] - Bob can send and recv audio
a=rtpmap:109 opus/48000/2	[RFC7587] Opus Codec
a=rtpmap:0 PCMU/8000	[RFC3551] PCMU Audio Codec
a=rtpmap:8 PCMA/8000	[RFC3551] PCMA Audio Codec
a=maxptime:120	[RFC4566]
a=ice-ufrag:05067423	[I-D.ietf-mmusic-ice-sip-sdp] - ICE user fragment
a=ice-pwd:1747d1ee3474a28a397a4c3f3af08a068	[I-D.ietf-mmusic-ice-sip-sdp] - ICE password parameter
a=fingerprint:sha-256 6B:8B:F0:65:5F:78:E2:51:3B:AC:6F:F3:3F:46:1B:35:DC:B8:5F:64:1A:24:C2:43:F0:A1:58:D0:A1:2C:19:08	[RFC8122] - DTLS Fingerprint for SRTP
a=setup:active	[RFC5763] - Bob is the DTLS client
a=tls-id:CJ6FF9ZZMJW7MDRJIR7XVIQM48GE1G31	[I-D.ietf-mmusic-dtls-sdp]
a=rtcp-mux	[RFC5761] - Bob can perform RTP/RTCP Muxing on port 49203
a=rtcp-rsize	[RFC5506] - Bob intends to use reduced size RTCP for this session
a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-level	[RFC6464] Bob supports audio level RTP header extension as well
a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid	[I-D.ietf-mmusic-sdp-bundle-negotiation]
a=candidate:0 1 UDP 2122194687 198.51.100.7 51556 typ host	[I-D.ietf-mmusic-ice-sip-sdp] - RTP/RTCP Host ICE Candidate
a=candidate:1 1 UDP 1685987071 203.0.113.77 49203 typ srflx raddr 198.51.100.7 rport 51556	[I-D.ietf-mmusic-ice-sip-sdp] - RTP/RTCP Server Reflexive ICE Candidate
a=end-of-candidates	[I-D.ietf-mmusic-trickle-ice]

5.2.2. Audio/Video Session

Alice and Bob establish a two-way audio and video session with Opus as the audio codec and H.264 as the video codec.¶


         Two-way Audio/Video Session

Alice                                       Bob
|                                            |
|                                            |
|offer(Audio:Opus,PCMU,PCMA Video:H.264,VP8) |
|------------------------------------------->|
|                                            |
|                                            |
|      answer(Audio:Opus,Video:H.264)        |
|<-------------------------------------------|
|                                            |
|                                            |
|     Two-way Opus Audio, H.264 Video        |
|............................................|
|                                            |

5.2.2.1. IPv4 Audio/Video Session

This section shows the IPv4-only offer/answer exchange.¶

Table 3: 5.2.2.1 SDP Offer
Offer SDP Contents	RFC#/Notes
v=0	[RFC4566]
o=- 20518 0 IN IP4 0.0.0.0	[RFC4566] - Session Origin Information
s=-	[RFC4566]
t=0 0	[RFC4566]
a=group:BUNDLE audio video	[I-D.ietf-mmusic-sdp-bundle-negotiation]
a=group:LS audio video	[RFC5888] - Alice wants to lip sync her audio and video streams
a=ice-options:trickle	[I-D.ietf-mmusic-trickle-ice]
a=ice-options:ice2	[RFC8445]
**** Audio m=line *******	*****************************
m=audio 54609 UDP/TLS/RTP/SAVPF 109 0 8	[RFC4566]
c=IN IP4 203.0.113.141	[RFC4566]
a=mid:audio	[RFC5888]
a=msid:ma ta	[I-D.ietf-mmusic-msid] Identifies MediaStream ID (ma) and MediaStreamTrack ID (ta)
a=sendrecv	[RFC3264] - Alice can send and recv audio
a=rtpmap:109 opus/48000/2	[RFC7587] - Opus Codec 48 kHz, 2 channels
a=rtpmap:0 PCMU/8000	[RFC3551] PCMU Audio Codec
a=rtpmap:8 PCMA/8000	[RFC3551] PCMA Audio Codec
a=maxptime:120	[RFC4566]
a=ice-ufrag:074c6550	[I-D.ietf-mmusic-ice-sip-sdp] - ICE user fragment
a=ice-pwd:a28a397a4c3f31747d1ee3474af08a068	[I-D.ietf-mmusic-ice-sip-sdp] - ICE password parameter
a=fingerprint:sha-256 19:E2:1C:3B:4B:9F:81:E6:B8:5C:F4:A5:A8:D8:73:04:BB:05:2F:70:9F:04:A9:0E:05:E9:26:33:E8:70:88:A2	[RFC8122] - DTLS Fingerprint for SRTP
a=setup:actpass	[RFC5763] - Alice can act as DTLS client or server
a=tls-id:89J2LRATQ3ULA24G9AHWVR31VJWSLB68	[I-D.ietf-mmusic-dtls-sdp]
a=rtcp-mux	[RFC5761] - Alice can perform RTP/RTCP Muxing
a=rtcp-mux-only	[I-D.ietf-mmusic-mux-exclusive]
a=rtcp-rsize	[RFC5506] - Alice intends to use reduced size RTCP for this session
a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-level	[RFC6464]
a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid	[I-D.ietf-mmusic-sdp-bundle-negotiation]
a=candidate:0 1 UDP 2122194687 192.0.2.4 61665 typ host	[I-D.ietf-mmusic-ice-sip-sdp] - RTP/RTCP Host Candidate
a=candidate:1 1 UDP 1685987071 203.0.113.141 54609 typ srflx raddr 192.0.2.4 rport 61665	[I-D.ietf-mmusic-ice-sip-sdp] - RTP/RTCP Server Reflexive ICE Candidate
a=end-of-candidates	[I-D.ietf-mmusic-trickle-ice]
**** Video m=line *******	*****************************
m=video 0 UDP/TLS/RTP/SAVPF 99 120	[RFC4566]
c=IN IP4 203.0.113.141	[RFC4566]
a=bundle-only	[I-D.ietf-mmusic-sdp-bundle-negotiation]
a=mid:video	[RFC5888]
a=msid:ma tb	Identifies MediaStream ID (ma) and MediaStreamTrack ID (tb)
a=sendrecv	[RFC3264] - Alice can send and recv video
a=rtpmap:99 H264/90000	[RFC6184] - H.264 Video Codec
a=fmtp:99 profile-level-id=4d0028;packetization-mode=1	[RFC6184]
a=rtpmap:120 VP8/90000	[RFC7741] - VP8 video codec
a=rtcp-fb:99 nack	[RFC4585] - Indicates NACK RTCP feedback support
a=rtcp-fb:99 nack pli	[RFC4585] - Indicates support for Picture loss Indication and NACK
a=rtcp-fb:99 ccm fir	[RFC5104] - Full Intra Frame Request-Codec Control Message support
a=rtcp-fb:120 nack	[RFC4585] - Indicates NACK RTCP feedback support
a=rtcp-fb:120 nack pli	[RFC4585] - Indicates support for Picture loss Indication and NACK
a=rtcp-fb:120 ccm fir	[RFC5104] - Full Intra Request-Codec Control Message support
a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid	[I-D.ietf-mmusic-sdp-bundle-negotiation]

Table 4: 5.2.2.1 SDP Answer
Answer SDP Contents	RFC#/Notes
v=0	[RFC4566]
o=- 16833 0 IN IP4 0.0.0.0	[RFC4566] - Session Origin Information
s=-	[RFC4566]
t=0 0	[RFC4566]
a=group:BUNDLE audio video	[I-D.ietf-mmusic-sdp-bundle-negotiation]
a=group:LS audio video	[RFC5888] - Bob agrees to do the same
a=ice-options:trickle	[I-D.ietf-mmusic-trickle-ice]
a=ice-options:ice2	[RFC8445]
**** Audio m=line *******	*****************************
m=audio 49203 UDP/TLS/RTP/SAVPF 109	[RFC4566]
c=IN IP4 203.0.113.77	[RFC4566]
a=mid:audio	[RFC5888]
a=msid:ma ta	Identifies MediaStream ID (ma) and MediaStreamTrack ID (ta)
a=sendrecv	[RFC3264] - Bob can send and recv audio
a=rtpmap:109 opus/48000/2	[RFC7587] - Bob accepts only Opus Codec
a=maxptime:120	[RFC4566]
a=ice-ufrag:c300d85b	[I-D.ietf-mmusic-ice-sip-sdp] - ICE username frag
a=ice-pwd:de4e99bd291c325921d5d47efbabd9a2	[I-D.ietf-mmusic-ice-sip-sdp] - ICE password
a=fingerprint:sha-256 6B:8B:F0:65:5F:78:E2:51:3B:AC:6F:F3:3F:46:1B:35:DC:B8:5F:64:1A:24:C2:43:F0:A1:58:D0:A1:2C:19:08	[RFC8122] - DTLS Fingerprint for SRTP
a=setup:active	[RFC5763] - Bob is the DTLS client
a=tls-id:CJ6FF9ZZMJW7MDRJIR7XVIQM48GE1G31	[I-D.ietf-mmusic-dtls-sdp]
a=rtcp-mux	[RFC5761] - Bob can perform RTP/RTCP Muxing
a=rtcp-mux-only	[I-D.ietf-mmusic-mux-exclusive]
a=rtcp-rsize	[RFC5506] - Bob intends to use reduced size RTCP for this session
a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-level	[RFC6464]
a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid	[I-D.ietf-mmusic-sdp-bundle-negotiation]
a=candidate:0 1 UDP 3618095783 198.51.100.7 49203 typ host	[I-D.ietf-mmusic-ice-sip-sdp] - RTP/RTCP Host ICE Candidate
a=candidate:1 1 UDP 565689203 203.0.113.77 49203 typ srflx raddr 198.51.100.7 rport 51556	[I-D.ietf-mmusic-ice-sip-sdp] - RTP/RTCP Server Reflexive ICE Candidate
a=end-of-candidates	[I-D.ietf-mmusic-trickle-ice]
**** Video m=line *******	*****************************
m=video 0 UDP/TLS/RTP/SAVPF 99	[RFC4566]
c=IN IP4 203.0.113.77	[RFC4566]
a=bundle-only	[I-D.ietf-mmusic-sdp-bundle-negotiation]
a=mid:video	[RFC5888]
a=msid:ma tb	Identifies MediaStream ID (ma) and MediaStreamTrack ID (tb)
a=sendrecv	[RFC3264] - Bob can send and recv video
a=rtpmap:99 H264/90000	[RFC6184] - Bob accepts H.264 Video Codec.
a=fmtp:99 profile-level-id=4d0028;packetization-mode=1	[RFC6184]
a=rtcp-fb:99 nack	[RFC4585] - Indicates support for NACK-based RTCP feedback
a=rtcp-fb:99 nack pli	[RFC4585] - Indicates support for Picture loss Indication and NACK
a=rtcp-fb:99 ccm fir	[RFC5104] - Full Intra Request-Codec Control Message support
a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid	[I-D.ietf-mmusic-sdp-bundle-negotiation]

5.2.2.2. Dual Stack Audio/Video Session

This section captures offer/answer exchange when Alice and Bob support both IPv4 and IPv6 host addresses.¶

Table 5: 5.2.2.2 SDP Offer
Offer SDP Contents	RFC#/Notes
v=0	[RFC4566]
o=- 20518 0 IN IP4 0.0.0.0	[RFC4566] - Session Origin Information
s=-	[RFC4566]
t=0 0	[RFC4566]
a=group:BUNDLE audio video	[I-D.ietf-mmusic-sdp-bundle-negotiation]
a=group:LS audio video	[RFC5888] - Alice wants to lip sync her audio and video streams
a=ice-options:trickle	[I-D.ietf-mmusic-trickle-ice]
a=ice-options:ice2	[RFC8445]
**** Audio m=line *******	*****************************
m=audio 54609 UDP/TLS/RTP/SAVPF 109 0 8	[RFC4566]
c=IN IP4 203.0.113.141	[RFC4566]
a=mid:audio	[RFC5888]
a=msid:ma ta	Identifies MediaStream ID (ma) and MediaStreamTrack ID (ta)
a=sendrecv	[RFC3264] - Alice can send and recv audio
a=rtpmap:109 opus/48000/2	[RFC7587] - Opus Codec 48 kHz, 2 channels
a=rtpmap:0 PCMU/8000	[RFC3551] PCMU Audio Codec
a=rtpmap:8 PCMA/8000	[RFC3551] PCMA Audio Codec
a=maxptime:120	[RFC4566]
a=ice-ufrag:074c6550	[I-D.ietf-mmusic-ice-sip-sdp] - ICE user fragment
a=ice-pwd:a28a397a4c3f31747d1ee3474af08a068	[I-D.ietf-mmusic-ice-sip-sdp] - ICE password parameter
a=fingerprint:sha-256 19:E2:1C:3B:4B:9F:81:E6:B8:5C:F4:A5:A8:D8:73:04:BB:05:2F:70:9F:04:A9:0E:05:E9:26:33:E8:70:88:A2	[RFC8122] - DTLS Fingerprint for SRTP
a=setup:actpass	[RFC5763] - Alice can act as DTLS client or server
a=tls-id:89J2LRATQ3ULA24G9AHWVR31VJWSLB68	[I-D.ietf-mmusic-dtls-sdp]
a=rtcp-mux	[RFC5761] - Alice can perform RTP/RTCP Muxing
a=rtcp-mux-only	[I-D.ietf-mmusic-mux-exclusive]
a=rtcp-rsize	[RFC5506] - Alice intends to use reduced size RTCP for this session
a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-level	[RFC6464]
a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid	[I-D.ietf-mmusic-sdp-bundle-negotiation]
a=candidate:0 1 UDP 2122194687 192.0.2.4 61665 typ host	[I-D.ietf-mmusic-ice-sip-sdp] - RTP/RTCP Host Candidate
a=candidate:0 1 UDP 2122194687 2001:db8:8101:3a55:4858:a2a9:22ff:99b9 61665 typ host	[I-D.ietf-mmusic-ice-sip-sdp] - RTP/RTCP IPv6 Host Candidate
a=end-of-candidates	[I-D.ietf-mmusic-trickle-ice]
**** Video m=line *******	*****************************
m=video 0 UDP/TLS/RTP/SAVPF 99 120	[RFC4566]
c=IN IP4 203.0.113.141	[RFC4566]
a=bundle-only	[I-D.ietf-mmusic-sdp-bundle-negotiation]
a=mid:video	[RFC5888]
a=msid:ma tb	Identifies MediaStream ID (ma) and MediaStreamTrack ID (tb)
a=sendrecv	[RFC3264] - Alice can send and recv video
a=rtpmap:99 H264/90000	[RFC6184] - H.264 Video Codec
a=fmtp:99 profile-level-id=4d0028;packetization-mode=1	[RFC6184]
a=rtpmap:120 VP8/90000	[RFC7741] - VP8 video codec
a=rtcp-fb:99 nack	[RFC4585] - Indicates NACK RTCP feedback support
a=rtcp-fb:99 nack pli	[RFC4585] - Indicates support for Picture loss Indication and NACK
a=rtcp-fb:99 ccm fir	[RFC5104] - Full Intra Request-Codec Control Message support
a=rtcp-fb:120 nack	[RFC4585] - Indicates NACK RTCP feedback support
a=rtcp-fb:120 nack pli	[RFC4585] - Indicates support for Picture loss Indication and NACK
a=rtcp-fb:120 ccm fir	[RFC5104] - Full Intra Request-Codec Control Message support
a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid	[I-D.ietf-mmusic-sdp-bundle-negotiation]

Table 6: 5.2.2.2 SDP Answer
Answer SDP Contents	RFC#/Notes
v=0	[RFC4566]
o=- 16833 0 IN IP4 0.0.0.0	[RFC4566] - Session Origin Information
s=-	[RFC4566]
t=0 0	[RFC4566]
a=group:BUNDLE audio video	[I-D.ietf-mmusic-sdp-bundle-negotiation]
a=group:LS audio video	[RFC5888] - Bob agrees to do the same
a=ice-options:trickle	[I-D.ietf-mmusic-trickle-ice]
a=ice-options:ice2	[RFC8445]
**** Audio m=line *******	*****************************
m=audio 49203 UDP/TLS/RTP/SAVPF 109	[RFC4566]
c=IN IP4 203.0.113.77	[RFC4566]
a=mid:audio	[RFC5888]
a=msid:ma ta	Identifies MediaStream ID (ma) and MediaStreamTrack ID (ta)
a=sendrecv	[RFC3264] - Bob can send and recv audio
a=rtpmap:109 opus/48000/2	[RFC7587] - Bob accepts only Opus Codec
a=maxptime:120	[RFC4566]
a=ice-ufrag:c300d85b	[I-D.ietf-mmusic-ice-sip-sdp] - ICE username frag
a=ice-pwd:de4e99bd291c325921d5d47efbabd9a2	[I-D.ietf-mmusic-ice-sip-sdp] - ICE password
a=fingerprint:sha-256 6B:8B:F0:65:5F:78:E2:51:3B:AC:6F:F3:3F:46:1B:35:DC:B8:5F:64:1A:24:C2:43:F0:A1:58:D0:A1:2C:19:08	[RFC8122] - DTLS Fingerprint for SRTP
a=setup:active	[RFC5763] - Bob is the DTLS client
a=tls-id:CJ6FF9ZZMJW7MDRJIR7XVIQM48GE1G31	[I-D.ietf-mmusic-dtls-sdp]
a=rtcp-mux	[RFC5761] - Bob can perform RTP/RTCP Muxing
a=rtcp-mux-only	[I-D.ietf-mmusic-mux-exclusive]
a=rtcp-rsize	[RFC5506] - Bob intends to use reduced size RTCP for this session
a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-level	[RFC6464]
a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid	[I-D.ietf-mmusic-sdp-bundle-negotiation]
a=candidate:0 1 UDP 3618095783 198.51.100.7 49203 typ host	[I-D.ietf-mmusic-ice-sip-sdp] - RTP/RTCP Host ICE Candidate
a=candidate:0 1 UDP 3618095783 2001:db8:30c:1266:5916:3779:22f6:77f7 49203 typ host	[I-D.ietf-mmusic-ice-sip-sdp] - RTP/RTCP IPv6 Host ICE Candidate
a=end-of-candidates	[I-D.ietf-mmusic-trickle-ice]
**** Video m=line *******	*****************************
m=video 0 UDP/TLS/RTP/SAVPF 99	[RFC4566]
c=IN IP4 203.0.113.77	[RFC4566]
a=bundle-only	[I-D.ietf-mmusic-sdp-bundle-negotiation]
a=mid:video	[RFC5888]
a=msid:ma tb	Identifies MediaStream ID (ma) and MediaStreamTrack ID (tb)
a=sendrecv	[RFC3264] - Bob can send and recv video
a=rtpmap:99 H264/90000	[RFC6184] - Bob accepts H.264 Video Codec.
a=fmtp:99 profile-level-id=4d0028;packetization-mode=1	[RFC6184]
a=rtcp-fb:99 nack	[RFC4585] - Indicates support for NACK-based RTCP feedback
a=rtcp-fb:99 nack pli	[RFC4585] - Indicates support for Picture loss Indication and NACK
a=rtcp-fb:99 ccm fir	[RFC5104] - Full Intra Request- Codec Control Message support
a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid	[I-D.ietf-mmusic-sdp-bundle-negotiation]

5.2.3. Data-only Session

This scenario illustrates the SDP negotiated to set up a data-only session based on the SCTP Data Channel, thus enabling use cases such as file transfer or real-time game control, for example.¶


      Two-way Data channel Session

Alice                            Bob
|                                 |
|                                 |
|                                 |
|      offer(Data Channel)        |
|-------------------------------->|
|                                 |
|                                 |
|      answer(Data Channel)       |
|<--------------------------------|
|                                 |
|                                 |
| Two-way SCTP-based data channel |
|.................................|
|                                 |
|                                 |

Table 7: 5.2.3 SDP Offer
Offer SDP Contents	RFC#/Notes
v=0	[RFC4566]
o=- 20518 0 IN IP4 0.0.0.0	[RFC4566] - Session Origin Information
s=-	[RFC4566]
t=0 0	[RFC4566]
a=group:BUNDLE data	[I-D.ietf-mmusic-sdp-bundle-negotiation]
a=ice-options:trickle	[I-D.ietf-mmusic-trickle-ice]
a=ice-options:ice2	[RFC8445]
**** Application m=line *******	*****************************
m=application 54609 UDP/DTLS/SCTP webrtc-datachannel	[I-D.ietf-rtcweb-data-channel]
c=IN IP4 203.0.113.141	[RFC4566]
a=mid:data	[RFC5888]
a=sendrecv	[RFC3264] - Alice can send and recv non-media data
a=sctp-port:5000	[I-D.ietf-mmusic-sctp-sdp]
a=max-message-size:100000	[I-D.ietf-mmusic-sctp-sdp]
a=setup:actpass	[RFC5763] - Alice can act as DTLS client or server
a=tls-id:89J2LRATQ3ULA24G9AHWVR31VJWSLB68	[I-D.ietf-mmusic-dtls-sdp]
a=ice-ufrag:074c6550	[I-D.ietf-mmusic-ice-sip-sdp] - Session Level ICE parameter
a=ice-pwd:a28a397a4c3f31747d1ee3474af08a068	[I-D.ietf-mmusic-ice-sip-sdp] - Session Level ICE parameter
a=fingerprint:sha-256 19:E2:1C:3B:4B:9F:81:E6:B8:5C:F4:A5:A8:D8:73:04:BB:05:2F:70:9F:04:A9:0E:05:E9:26:33:E8:70:88:A2	[RFC8122] - Session DTLS Fingerprint for SRTP
a=candidate:0 1 UDP 2113667327 192.0.2.4 61665 typ host	[I-D.ietf-mmusic-ice-sip-sdp]
a=candidate:1 1 UDP 1694302207 203.0.113.141 54609 typ srflx raddr 192.0.2.4 rport 61665	[I-D.ietf-mmusic-ice-sip-sdp]
a=end-of-candidates	[I-D.ietf-mmusic-trickle-ice]

Table 8: 5.2.3 SDP Answer
Answer SDP Contents	RFC#/Notes
v=0	[RFC4566]
o=- 16833 0 IN IP4 0.0.0.0	[RFC4566] - Session Origin Information
s=-	[RFC4566]
t=0 0	[RFC4566]
a=group:BUNDLE data	[I-D.ietf-mmusic-sdp-bundle-negotiation]
**** Application m=line *******	*****************************
m=application 49203 UDP/DTLS/SCTP webrtc-datachannel	[I-D.ietf-mmusic-sctp-sdp]
c=IN IP4 203.0.113.77	[RFC4566]
a=mid:data	[RFC5888]
a=sendrecv	[RFC3264] - Bob can send and recv non-media data
a=sctp-port:5000	[I-D.ietf-mmusic-sctp-sdp]
a=max-message-size:100000	[I-D.ietf-mmusic-sctp-sdp]
a=setup:active	[RFC5763] - Bob is the DTLS client
a=tls-id:CJ6FF9ZZMJW7MDRJIR7XVIQM48GE1G31	[I-D.ietf-mmusic-dtls-sdp]
a=ice-ufrag:c300d85b	[I-D.ietf-mmusic-ice-sip-sdp] - Session Level ICE username frag
a=ice-pwd:de4e99bd291c325921d5d47efbabd9a2	[I-D.ietf-mmusic-ice-sip-sdp] - Session Level ICE password
a=fingerprint:sha-256 6B:8B:F0:65:5F:78:E2:51:3B:AC:6F:F3:3F:46:1B:35:DC:B8:5F:64:1A:24:C2:43:F0:A1:58:D0:A1:2C:19:08	[RFC8122] - Session DTLS Fingerprint for SRTP
a=candidate:0 1 UDP 2113667327 198.51.100.7 51556 typ host	[I-D.ietf-mmusic-ice-sip-sdp]
a=candidate:1 1 UDP 1694302207 203.0.113.77 49203 typ srflx raddr 198.51.100.7 rport 51556	[I-D.ietf-mmusic-ice-sip-sdp]
a=end-of-candidates	[I-D.ietf-mmusic-trickle-ice]

5.2.4. Audio Call On Hold

Alice calls Bob, but when Bob answers he places Alice on hold by setting the SDP direction attribute to a=inactive in the answer.¶


           Audio On Hold

Alice                            Bob
|                                 |
|                                 |
|      offer(Audio:Opus)          |
|-------------------------------->|
|                                 |
|                                 |
|  answer(Audio:Opus,a=inactive)  |
|<--------------------------------|
|                                 |
|                                 |
|      One-way Opus Audio         |
|.................................|
|                                 |
|

Table 9: 5.2.4 SDP Offer
Offer SDP Contents	RFC#/Notes
v=0	[RFC4566]
o=- 20518 0 IN IP4 0.0.0.0	[RFC4566] - Session Origin Information
s=-	[RFC4566]
t=0 0	[RFC4566]
a=group:BUNDLE audio	[I-D.ietf-mmusic-sdp-bundle-negotiation]
a=ice-options:trickle	[I-D.ietf-mmusic-trickle-ice]
a=ice-options:ice2	[RFC8445]
**** Audio m=line *******	*****************************
m=audio 54609 UDP/TLS/RTP/SAVPF 109	[RFC4566]
c=IN IP4 203.0.113.141	[RFC4566]
a=mid:audio	[RFC5888]
a=msid:ma ta	Identifies MediaStream ID (ma) and MediaStreamTrack ID (ta)
a=sendrecv	[RFC3264] - Alice can send and recv audio
a=rtpmap:109 opus/48000/2	[RFC7587] - Opus Codec 48 kHz, 2 channels
a=maxptime:120	[RFC4566]
a=ice-ufrag:074c6550	[I-D.ietf-mmusic-ice-sip-sdp] - ICE user fragment
a=ice-pwd:a28a397a4c3f31747d1ee3474af08a068	[I-D.ietf-mmusic-ice-sip-sdp] - ICE password
a=fingerprint:sha-256 19:E2:1C:3B:4B:9F:81:E6:B8:5C:F4:A5:A8:D8:73:04:BB:05:2F:70:9F:04:A9:0E:05:E9:26:33:E8:70:88:A2	[RFC8122] - DTLS Fingerprint for SRTP
a=setup:actpass	[RFC5763] - Alice can act as DTLS client or server
a=tls-id:89J2LRATQ3ULA24G9AHWVR31VJWSLB68	[I-D.ietf-mmusic-dtls-sdp]
a=rtcp-mux	[RFC5761] - Alice can perform RTP/RTCP Muxing
a=rtcp-mux-only	[I-D.ietf-mmusic-mux-exclusive]
a=rtcp-rsize	[RFC5506]
a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-level	[RFC6464]
a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid	[I-D.ietf-mmusic-sdp-bundle-negotiation]
a=candidate:0 1 UDP 2113667327 192.0.2.4 61665 typ host	[I-D.ietf-mmusic-ice-sip-sdp]
a=candidate:1 1 UDP 1685987071 203.0.113.141 54609 typ srflx raddr 192.0.2.4 rport 61665	[I-D.ietf-mmusic-ice-sip-sdp]
a=end-of-candidates	[I-D.ietf-mmusic-trickle-ice]

Table 10: 5.2.4 SDP Answer
Answer SDP Contents	RFC#/Notes
v=0	[RFC4566]
o=- 16833 0 IN IP4 0.0.0.0	[RFC4566] - Session Origin Information
s=-	[RFC4566]
t=0 0	[RFC4566]
a=group:BUNDLE audio	[I-D.ietf-mmusic-sdp-bundle-negotiation]
**** Audio m=line *******	*****************************
m=audio 49203 UDP/TLS/RTP/SAVPF 109	[RFC4566]
c=IN IP4 203.0.113.77	[RFC4566]
a=mid:audio	[RFC5888]
a=msid:ma ta	Identifies MediaStream ID (ma) and MediaStreamTrack ID (ta)
a=inactive	[RFC3264] - Bob puts call On Hold
a=rtpmap:109 opus/48000/2	[RFC7587] - Bob accepts Opus Codec
a=maxptime:120	[RFC4566]
a=ice-ufrag:c300d85b	[I-D.ietf-mmusic-ice-sip-sdp] - ICE username frag
a=ice-pwd:de4e99bd291c325921d5d47efbabd9a2	[I-D.ietf-mmusic-ice-sip-sdp] - ICE password
a=fingerprint:sha-256 6B:8B:F0:65:5F:78:E2:51:3B:AC:6F:F3:3F:46:1B:35:DC:B8:5F:64:1A:24:C2:43:F0:A1:58:D0:A1:2C:19:08	[RFC8122] - DTLS Fingerprint for SRTP
a=setup:active	[RFC5763] - Bob is the DTLS client
a=tls-id:CJ6FF9ZZMJW7MDRJIR7XVIQM48GE1G31	[I-D.ietf-mmusic-dtls-sdp]
a=rtcp-mux	[RFC5761] - Bob can perform RTP/RTCP Muxing
a=rtcp-mux-only	[I-D.ietf-mmusic-mux-exclusive]
a=rtcp-rsize	[RFC5506]
a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-level	[RFC6464]
a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid	[I-D.ietf-mmusic-sdp-bundle-negotiation]
a=candidate:0 1 UDP 2113667327 198.51.100.7 51556 typ host	[I-D.ietf-mmusic-ice-sip-sdp] - Host candidate
a=candidate:1 1 UDP 1685987071 203.0.113.141 49203 typ srflx raddr 198.51.100.7 rport 51556	[I-D.ietf-mmusic-ice-sip-sdp] - Server Reflexive candidate
a=end-of-candidates	[I-D.ietf-mmusic-trickle-ice]

5.2.5. Audio with DTMF Session

In this example, Alice wishes to establish two separate audio streams, one for normal audio and the other for telephone-events. Alice offers the first audio stream with three codecs and the other with [RFC4733] tones (for DTMF). Bob accepts both the audio streams by choosing Opus as the audio codec and telephone-event for the other stream.¶


            Audio Session with DTMF

Alice                                              Bob
|                                                   |
|                                                   |
|                                                   |
|  offer(Audio:Opus,PCMU,PCMA Audio:telephone-event)|
|-------------------------------------------------->|
|                                                   |
|                                                   |
|    answer(Audio:Opus, Audio:telephone-event)      |
|<--------------------------------------------------|
|                                                   |
|                                                   |
|   Opus audio stream and telephone-event stream    |
|...................................................|
|                                                   |

Table 11: 5.2.5 SDP Offer
Offer SDP Contents	RFC#/Notes
v=0	[RFC4566]
o=- 20518 0 IN IP4 0.0.0.0	[RFC4566] - Session Origin Information
s=-	[RFC4566]
t=0 0	[RFC4566]
a=group:BUNDLE audio dtmf	[I-D.ietf-mmusic-sdp-bundle-negotiation]
a=ice-options:trickle	[I-D.ietf-mmusic-trickle-ice]
a=ice-options:ice2	[RFC8445]
**** Audio m=line *******	*****************************
m=audio 54609 UDP/TLS/RTP/SAVPF 109 0 8	[RFC4566]
c=IN IP4 203.0.113.141	[RFC4566]
a=mid:audio	[RFC5888]
a=msid:ma ta	Identifies MediaStream ID (ma) and MediaStreamTrack ID (ta)
a=sendrecv	[RFC3264] - Alice can send and recv audio
a=rtpmap:109 opus/48000/2	[RFC7587] - Opus Codec 48 kHz, 2 channels
a=rtpmap:0 PCMU/8000	[RFC3551] PCMU audio Codec
a=rtpmap:8 PCMA/8000	[RFC3551] PCMA audio Codec
a=maxptime:120	[RFC4566]
a=ice-ufrag:074c6550	[I-D.ietf-mmusic-ice-sip-sdp] - ICE user fragment
a=ice-pwd:a28a397a4c3f31747d1ee3474af08a068	[I-D.ietf-mmusic-ice-sip-sdp] - ICE password parameter
a=fingerprint:sha-256 19:E2:1C:3B:4B:9F:81:E6:B8:5C:F4:A5:A8:D8:73:04:BB:05:2F:70:9F:04:A9:0E:05:E9:26:33:E8:70:88:A2	[RFC8122] - DTLS Fingerprint for SRTP
a=setup:actpass	[RFC5763] - Alice can act as DTLS client or server
a=tls-id:89J2LRATQ3ULA24G9AHWVR31VJWSLB68	[I-D.ietf-mmusic-dtls-sdp]
a=rtcp-mux	[RFC5761] - Alice can perform RTP/RTCP Muxing
a=rtcp-mux-only	[I-D.ietf-mmusic-mux-exclusive]
a=rtcp-rsize	[RFC5506]
a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-level	[RFC6464]
a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid	[I-D.ietf-mmusic-sdp-bundle-negotiation]
a=candidate:0 1 UDP 2122194687 192.0.2.4 61665 typ host	[I-D.ietf-mmusic-ice-sip-sdp]
a=candidate:1 1 UDP 1685987071 203.0.113.141 54609 typ srflx raddr 192.0.2.4 rport 61665	[I-D.ietf-mmusic-ice-sip-sdp]
a=end-of-candidates	[I-D.ietf-mmusic-trickle-ice]
**** DTMF m=line *******	*****************************
m=audio 0 UDP/TLS/RTP/SAVPF 126	[RFC4566]
c=IN IP4 203.0.113.141	[RFC4566]
a=bundle-only	[I-D.ietf-mmusic-sdp-bundle-negotiation]
a=mid:dtmf	[RFC5888]
a=msid:ma tb	Identifies MediaStream ID (ma) and MediaStreamTrack ID (tb)
a=sendonly	[RFC3264] - Alice can send DTMF Events
a=rtpmap:126 telephone-event/8000	[RFC4733]
a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid	[I-D.ietf-mmusic-sdp-bundle-negotiation]

Table 12: 5.2.5 SDP Answer
Answer SDP Contents	RFC#/Notes
v=0	[RFC4566]
o=- 16833 0 IN IP4 0.0.0.0	[RFC4566] - Session Origin Information
s=-	[RFC4566]
t=0 0	[RFC4566]
a=group:BUNDLE audio dtmf	[I-D.ietf-mmusic-sdp-bundle-negotiation]
**** Audio m=line *******	*****************************
m=audio 49203 UDP/TLS/RTP/SAVPF 109	[RFC4566]
c=IN IP4 203.0.113.77	[RFC4566]
a=mid:audio	[RFC5888]
a=msid:ma ta	Identifies MediaStream ID (ma) and MediaStreamTrack ID (ta)
a=sendrecv	[RFC3264] - Bob can send and receive Opus audio
a=rtpmap:109 opus/48000/2	[RFC7587] - Bob accepts Opus Codec
a=maxptime:120	[RFC4566]
a=ice-ufrag:c300d85b	[I-D.ietf-mmusic-ice-sip-sdp] - ICE username frag
a=ice-pwd:de4e99bd291c325921d5d47efbabd9a2	[I-D.ietf-mmusic-ice-sip-sdp] - ICE password
a=fingerprint:sha-256 6B:8B:F0:65:5F:78:E2:51:3B:AC:6F:F3:3F:46:1B:35:DC:B8:5F:64:1A:24:C2:43:F0:A1:58:D0:A1:2C:19:08	[RFC8122] - Fingerprint for SRTP
a=setup:active	[RFC5763] - Bob is the DTLS client
a=tls-id:CJ6FF9ZZMJW7MDRJIR7XVIQM48GE1G31	[I-D.ietf-mmusic-dtls-sdp]
a=rtcp-mux	[RFC5761] - Bob can perform RTP/RTCP Muxing on port 49203
a=rtcp-mux-only	[I-D.ietf-mmusic-mux-exclusive]
a=rtcp-rsize	[RFC5506] - Alice intends to use reduced-size RTCP for this session
a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-level	[RFC6464]
a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid	[I-D.ietf-mmusic-sdp-bundle-negotiation]
a=candidate:0 1 UDP 2122194687 198.51.100.7 51556 typ host	[I-D.ietf-mmusic-ice-sip-sdp]
a=candidate:1 1 UDP 1685987071 203.0.113.77 49203 typ srflx raddr 198.51.100.7 rport 51556	[I-D.ietf-mmusic-ice-sip-sdp]
a=end-of-candidates	[I-D.ietf-mmusic-trickle-ice]
**** DTMF m=line *******	*****************************
m=audio 0 UDP/TLS/RTP/SAVPF 126	[RFC4566]
c=IN IP4 203.0.113.77	[RFC4566]
a=bundle-only	[I-D.ietf-mmusic-sdp-bundle-negotiation]
a=mid:dtmf	[RFC5888]
a=msid:ma tb	Identifies MediaStream ID (ma) and MediaStreamTrack ID (tb)
a=recvonly	[RFC3264] - Alice can receive DTMF events
a=rtpmap:126 telephone-event/8000	[RFC4733]
a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid	[I-D.ietf-mmusic-sdp-bundle-negotiation]

5.2.6. One-way Audio/Video Session - Document Camera

In this scenario Alice and Bob engage in a One-way audio and video session with Bob receiving Alice's audio and her presentation slides as video stream.¶



   One-way Audio & Video Session - Document Camera


Alice                                                 Bob
|                                                      |
|                                                      |
|                                                      |
|   Alice offers send-only audio and video streams.    |
|  The video stream corresponds to her presentation    |
|                                                      |
|           offer(Audio:Opus, Video: VP8)              |
|----------------------------------------------------->|
|                                                      |
|                                                      |
|            (Audio:Opus, Video: VP8)                  |
|<-----------------------------------------------------|
|                                                      |
|                                                      |
|          One-way Opus Audio, VP8 Video               |
|......................................................|
|   Bob can hear Alice and see her presentation slides.|
|                                                      |
|                                                      |

Table 13: 5.2.6 SDP Offer
Offer SDP Contents	RFC#/Notes
v=0	[RFC4566]
o=- 20519 0 IN IP4 0.0.0.0	[RFC4566]
s=-	[RFC4566]
t=0 0	[RFC4566]
a=group:BUNDLE audio video	[I-D.ietf-mmusic-sdp-bundle-negotiation]
a=group:LS audio video	[RFC5888]
a=ice-options:trickle	[I-D.ietf-mmusic-trickle-ice]
a=ice-options:ice2	[RFC8445]
**** Audio m=line *******	*****************************
m=audio 54609 UDP/TLS/RTP/SAVPF 109	[RFC4566]
c=IN IP4 203.0.113.141	[RFC4566]
a=mid:audio	[RFC5888]
a=msid:ma ta	Identifies MediaStream ID (ma) and MediaStreamTrack ID (ta)
a=sendonly	[RFC3264] - Send-only audio stream
a=rtpmap:109 opus/48000/2	[RFC7587]
a=maxptime:120	[RFC4566]
a=ice-ufrag:074c6550	[I-D.ietf-mmusic-ice-sip-sdp]
a=ice-pwd:a28a397a4c3f31747d1ee3474af08a068	[I-D.ietf-mmusic-ice-sip-sdp]
a=fingerprint:sha-256 19:E2:1C:3B:4B:9F:81:E6:B8:5C:F4:A5:A8:D8:73:04:BB:05:2F:70:9F:04:A9:0E:05:E9:26:33:E8:70:88:A2	[RFC8122]
a=setup:actpass	[RFC5763] - Alice can act as DTLS client or server
a=tls-id:89J2LRATQ3ULA24G9AHWVR31VJWSLB68	[I-D.ietf-mmusic-dtls-sdp]
a=rtcp-mux	[RFC5761]
a=rtcp-mux-only	[I-D.ietf-mmusic-mux-exclusive]
a=rtcp-rsize	[RFC5506]
a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-level	[RFC6464]
a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid	[I-D.ietf-mmusic-sdp-bundle-negotiation]
a=candidate:0 1 UDP 2122194687 203.0.113.141 54609 typ host	[I-D.ietf-mmusic-ice-sip-sdp]
a=end-of-candidates	[I-D.ietf-mmusic-trickle-ice]
**** Video m=line *******	*****************************
m=video 0 UDP/TLS/RTP/SAVPF 120	[RFC4566]
c=IN IP4 203.0.113.141	[RFC4566]
a=bundle-only	[I-D.ietf-mmusic-sdp-bundle-negotiation]
a=mid:video	[RFC5888]
a=msid:ma tb	Identifies MediaStream ID (ma) and MediaStreamTrack ID (tb)
a=sendonly	[RFC3264] - Send-only video stream
a=rtpmap:120 VP8/90000	[RFC7741]
a=content:slides	[RFC4796] - Alice's presentation video stream
a=rtcp-fb:120 nack	[RFC4585]
a=rtcp-fb:120 nack pli	[RFC4585]
a=rtcp-fb:120 ccm fir	[RFC5104]
a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid	[I-D.ietf-mmusic-sdp-bundle-negotiation]

Table 14: 5.2.6 SDP Answer
Answer SDP Contents	RFC#/Notes
v=0	[RFC4566]
o=- 16833 0 IN IP4 0.0.0.0	[RFC4566]
s=-	[RFC4566]
t=0 0	[RFC4566]
a=group:BUNDLE audio video	[I-D.ietf-mmusic-sdp-bundle-negotiation]
a=group:LS audio video	[RFC5888]
a=ice-options:trickle	[I-D.ietf-mmusic-trickle-ice]
a=ice-options:ice2	[RFC8445]
**** Audio m=line *******	*****************************
m=audio 49203 UDP/TLS/RTP/SAVPF 109	[RFC4566]
c=IN IP4 203.0.113.77	[RFC4566]
a=mid:audio	[RFC5888]
a=msid:ma ta	Identifies MediaStream ID (ma) and MediaStreamTrack ID (ta)
a=recvonly	[RFC3264] - Receive-only audio stream
a=rtpmap:109 opus/48000/2	[RFC7587]
a=maxptime:120	[RFC4566]
a=ice-ufrag:c300d85b	[I-D.ietf-mmusic-ice-sip-sdp]
a=ice-pwd:de4e99bd291c325921d5d47efbabd9a2	[I-D.ietf-mmusic-ice-sip-sdp]
a=fingerprint:sha-256 6B:8B:F0:65:5F:78:E2:51:3B:AC:6F:F3:3F:46:1B:35:DC:B8:5F:64:1A:24:C2:43:F0:A1:58:D0:A1:2C:19:08	[RFC8122]
a=setup:active	[RFC5763] - Bob is the DTLS client
a=tls-id:CJ6FF9ZZMJW7MDRJIR7XVIQM48GE1G31	[I-D.ietf-mmusic-dtls-sdp]
a=rtcp-mux	[RFC5761]
a=rtcp-mux-only	[I-D.ietf-mmusic-mux-exclusive]
a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-level	[RFC6464]
a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid	[I-D.ietf-mmusic-sdp-bundle-negotiation]
a=candidate:0 1 UDP 2113667327 203.0.113.77 49203 typ host	[I-D.ietf-mmusic-ice-sip-sdp]
a=end-of-candidates	[I-D.ietf-mmusic-trickle-ice]
**** Video m=line *******	*****************************
m=video 0 UDP/TLS/RTP/SAVPF 120	[RFC4566]
c=IN IP4 203.0.113.77	[RFC4566]
a=bundle-only	[I-D.ietf-mmusic-sdp-bundle-negotiation]
a=mid:video	[RFC5888]
a=msid:ma tb	Identifies MediaStream ID (ma) and MediaStreamTrack ID (tb)
a=recvonly	[RFC3264]
a=rtpmap:120 VP8/90000	[RFC7741]
a=content:slides	[RFC4796] - presentation stream
a=rtcp-fb:120 nack	[RFC4585]
a=rtcp-fb:120 nack pli	[RFC4585]
a=rtcp-fb:120 ccm fir	[RFC5104]
a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid	[I-D.ietf-mmusic-sdp-bundle-negotiation]

5.2.7. Audio, Video Session with BUNDLE Support Unknown

In this example, since Alice is unsure of the Bob's support of the BUNDLE framework, the following steps are performed in order to negotiate and set up a BUNDLE Address for the session.¶

An SDP offer, in which Alice assigns unique addresses to each "m=" line in the BUNDLE group, and requests the answerer to select the offerer's BUNDLE address.¶
An SDP answer, in which Bob indicates support for BUNDLE, selects the offerer's BUNDLE address, selects its own BUNDLE address and associates it with each BUNDLED m=line within the BUNDLE group.¶

Once the offer/answer exchange completes, both Alice and Bob each end up using a single RTP session for both of the media streams.¶



 Two-way Secure Audio and Video with BUNDLE support unknown

Alice                                                 Bob
|                                                      |
|                                                      |
|   Alice offers BUNDLE support with unique addresses  |
|        for the audio and video m-line                |
|                                                      |
|                                                      |
|          offer(Audio:Opus Video:VP8)                 |
|----------------------------------------------------->|
|                                                      |Bob
|                                                      |supports
|                                                      |BUNDLE,
|                                                      |Uses
|                                                      |identical
|                                                      |address
|          answer(Audio:Opus Video:VP8)                |
|<-----------------------------------------------------|
|                                                      |
|    Two-way Call with Audio and Video Multiplexed     |
|......................................................|
|                                                      |

Table 15: 5.2.7 SDP Offer w/BUNDLE
Offer SDP Contents	RFC#/Notes
v=0	[RFC4566]
o=- 20518 0 IN IP4 0.0.0.0	[RFC4566]
s=-	[RFC4566]
t=0 0	[RFC4566]
a=group:BUNDLE audio video	[I-D.ietf-mmusic-sdp-bundle-negotiation] Alice supports grouping of m=lines under BUNDLE semantics
a=group:LS audio video	[RFC5888]
a=ice-options:trickle	[I-D.ietf-mmusic-trickle-ice]
a=ice-options:ice2	[RFC8445]
**** Audio m=line *******	*****************************
m=audio 54609 UDP/TLS/RTP/SAVPF 109	[RFC4566]
c=IN IP4 203.0.113.141	[RFC4566]
a=mid:audio	[RFC5888] Audio m=line part of BUNDLE group with a unique port number
a=msid:ma ta	Identifies MediaStream ID (ma) and MediaStreamTrack ID (ta)
a=sendrecv	[RFC3264]
a=rtpmap:109 opus/48000/2	[RFC7587]
a=maxptime:120	[RFC4566]
a=ice-ufrag:074c6550	[I-D.ietf-mmusic-ice-sip-sdp]
a=ice-pwd:a28a397a4c3f31747d1ee3474af08a068	[I-D.ietf-mmusic-ice-sip-sdp]
a=fingerprint:sha-256 19:E2:1C:3B:4B:9F:81:E6:B8:5C:F4:A5:A8:D8:73:04:BB:05:2F:70:9F:04:A9:0E:05:E9:26:33:E8:70:88:A2	[RFC8122]
a=setup:actpass	[RFC5763] - Alice can act as DTLS client or server
a=tls-id:89J2LRATQ3ULA24G9AHWVR31VJWSLB68	[I-D.ietf-mmusic-dtls-sdp]
a=rtcp-mux	[RFC5761]
a=rtcp:54610 IN IP4 203.0.113.141	[RFC3605] - RTCP port different from RTP Port
a=rtcp-rsize	[RFC5506]
a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-level	[RFC6464]
a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid	[I-D.ietf-mmusic-sdp-bundle-negotiation]
a=candidate:0 1 UDP 2122194687 192.0.2.4 61665 typ host	[I-D.ietf-mmusic-ice-sip-sdp] - RTP host candidate
a=candidate:1 1 UDP 1685987071 203.0.113.141 54609 typ srflx raddr 192.0.2.4 rport 61665	[I-D.ietf-mmusic-ice-sip-sdp] - RTP Server Reflexive candidate
a=candidate:0 2 UDP 2122194687 192.0.2.4 61666 typ host	[I-D.ietf-mmusic-ice-sip-sdp] - RTCP host candidate
a=candidate:1 2 UDP 1685987071 203.0.113.141 54610 typ srflx raddr 192.0.2.4 rport 61666	[I-D.ietf-mmusic-ice-sip-sdp] - RTCP Server Reflexive candidate
**** Video m=line *******	*****************************
m=video 62537 UDP/TLS/RTP/SAVPF 120	[RFC4566]
c=IN IP4 203.0.113.141	[RFC4566]
a=mid:video	[RFC5888] Video m=line part of the Bundle group with a unique port number
a=msid:ma tb	Identifies MediaStream ID (ma) and MediaStreamTrack ID (tb)
a=sendrecv	[RFC3264]
a=rtpmap:120 VP8/90000	[RFC7741]
a=ice-ufrag:6550074c	[I-D.ietf-mmusic-ice-sip-sdp]
a=ice-pwd:74af08a068a28a397a4c3f31747d1ee34	[I-D.ietf-mmusic-ice-sip-sdp]
a=fingerprint:sha-256 19:E2:1C:3B:4B:9F:81:E6:B8:5C:F4:A5:A8:D8:73:04:BB:05:2F:70:9F:04:A9:0E:05:E9:26:33:E8:70:88:A2	[RFC8122]
a=setup:actpass	[RFC5763] - Alice can act as DTLS client or server
a=tls-id:UKA29UQLTF69OJW4WNPNUO2Y0GF1FJOZ	[I-D.ietf-mmusic-dtls-sdp]
a=rtcp-mux	[RFC5761]
a=rtcp:62538 IN IP4 203.0.113.141	[RFC3605]
a=rtcp-rsize	[RFC5506]
a=rtcp-fb:120 nack	[RFC4585]
a=rtcp-fb:120 nack pli	[RFC4585]
a=rtcp-fb:120 ccm fir	[RFC5104]
a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid	[I-D.ietf-mmusic-sdp-bundle-negotiation]
a=candidate:0 1 UDP 2122194687 192.0.2.4 61886 typ host	[I-D.ietf-mmusic-ice-sip-sdp] - RTP Host candidate
a=candidate:1 1 UDP 1685987071 203.0.113.141 62537 typ srflx raddr 192.0.2.4 rport 61886	[I-D.ietf-mmusic-ice-sip-sdp] - RTP Server Reflexive candidate
a=candidate:0 2 UDP 2122194687 192.0.2.4 61888 typ host	[I-D.ietf-mmusic-ice-sip-sdp] - RTCP host candidate
a=candidate:1 2 UDP 1685987071 203.0.113.141 62538 typ srflx raddr 192.0.2.4 rport 61888	[I-D.ietf-mmusic-ice-sip-sdp] - RTCP Server Reflexive candidate

Table 16: 5.2.7 SDP Answer w/BUNDLE
Answer SDP Contents	RFC#/Notes
v=0	[RFC4566]
o=- 16833 0 IN IP4 0.0.0.0	[RFC4566]
s=-	[RFC4566]
t=0 0	[RFC4566]
a=group:BUNDLE audio video	[I-D.ietf-mmusic-sdp-bundle-negotiation] Bob supports BUNDLE semantics.
a=group:LS audio video	[RFC5888]
a=ice-options:trickle	[I-D.ietf-mmusic-trickle-ice]
a=ice-options:ice2	[RFC8445]
**** Audio m=line *******	*****************************
m=audio 49203 UDP/TLS/RTP/SAVPF 109	[RFC4566]
c=IN IP4 203.0.113.77	[RFC4566]
a=mid:audio	[RFC5888] Audio m=line part of the BUNDLE group
a=msid:ma ta	Identifies MediaStream ID (ma) and MediaStreamTrack ID (ta)
a=sendrecv	[RFC3264]
a=rtpmap:109 opus/48000/2	[RFC7587]
a=maxptime:120	[RFC4566]
a=ice-ufrag:c300d85b	[I-D.ietf-mmusic-ice-sip-sdp]
a=ice-pwd:de4e99bd291c325921d5d47efbabd9a2	[I-D.ietf-mmusic-ice-sip-sdp]
a=fingerprint:sha-256 6B:8B:F0:65:5F:78:E2:51:3B:AC:6F:F3:3F:46:1B:35:DC:B8:5F:64:1A:24:C2:43:F0:A1:58:D0:A1:2C:19:08	[RFC8122]
a=setup:active	[RFC5763] - Bob is the DTLS client
a=tls-id:CJ6FF9ZZMJW7MDRJIR7XVIQM48GE1G31	[I-D.ietf-mmusic-dtls-sdp]
a=rtcp-mux	[RFC5761]
a=rtcp-rsize	[RFC5506]
a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-level	[RFC6464]
a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid	[I-D.ietf-mmusic-sdp-bundle-negotiation]
a=candidate:0 1 UDP 2122194687 198.51.100.7 49203 typ host	[I-D.ietf-mmusic-ice-sip-sdp]
a=candidate:1 1 UDP 1685987071 203.0.113.77 51556 typ srflx raddr 198.51.100.7 rport 49203	[I-D.ietf-mmusic-ice-sip-sdp]
**** Video m=line *******	*****************************
m=video 0 UDP/TLS/RTP/SAVPF 120	[RFC4566]
c=IN IP4 203.0.113.77	[RFC4566]
a=bundle-only	[I-D.ietf-mmusic-sdp-bundle-negotiation]
a=mid:video	[RFC5888] Video m=line part of the BUNDLE group with the port from audio line repeated
a=msid:ma tb	Identifies MediaStream ID (ma) and MediaStreamTrack ID (tb)
a=sendrecv	[RFC3264]
a=rtpmap:120 VP8/90000	[RFC7741]
a=rtcp-fb:120 nack	[RFC4585]
a=rtcp-fb:120 nack pli	[RFC4585]
a=rtcp-fb:120 ccm fir	[RFC5104]
a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid	[I-D.ietf-mmusic-sdp-bundle-negotiation]

5.2.8. Audio, Video, and Data Session

This example shows SDP for negotiating a session with Audio, Video and data streams between Alice and Bob with BUNDLE support known.¶



    Audio,Video, and Data with BUNDLE support known

Alice                                       Bob
|                                            |
|                                            |
|   Alice indicates BUNDLE support with  an  |
|  identical address across all the m=lines  |
|                                            |
|                                            |
|     offer(Audio:Opus Video:VP8 Data)       |
|------------------------------------------->|
|                                            |Bob does
|                                            |the same
|    answer(Audio:Opus,Video:VP8 Data)       |
|<-------------------------------------------|
|                                            |
|                                            |
|                                            |
|    Two-way Audio,Video, Data multiplexed   |
|............................................|
|                                            |
|                                            |

Table 17: 5.2.8 SDP Offer
Offer SDP Contents	RFC#/Notes
v=0	[RFC4566]
o=- 20518 0 IN IP4 0.0.0.0	[RFC4566]
s=-	[RFC4566]
t=0 0	[RFC4566]
a=group:BUNDLE audio video data	[I-D.ietf-mmusic-sdp-bundle-negotiation]
a=group:LS audio video	[RFC5888]
a=ice-options:trickle	[I-D.ietf-mmusic-trickle-ice]
a=ice-options:ice2	[RFC8445]
**** Audio m=line *******	*****************************
m=audio 54609 UDP/TLS/RTP/SAVPF 109	[RFC4566]
c=IN IP4 203.0.113.141	[RFC4566]
a=msid:ma ta	Identifies MediaStream ID (ma) and MediaStreamTrack ID (ta)
a=mid:audio	[RFC5888]
a=sendrecv	[RFC3264]
a=rtpmap:109 opus/48000/2	[RFC7587]
a=maxptime:120	[RFC4566]
a=ice-ufrag:074c6550	[I-D.ietf-mmusic-ice-sip-sdp]
a=ice-pwd:a28a397a4c3f31747d1ee3474af08a068	[I-D.ietf-mmusic-ice-sip-sdp]
a=fingerprint:sha-256 19:E2:1C:3B:4B:9F:81:E6:B8:5C:F4:A5:A8:D8:73:04:BB:05:2F:70:9F:04:A9:0E:05:E9:26:33:E8:70:88:A2	[RFC8122]
a=setup:actpass	[RFC5763]
a=tls-id:89J2LRATQ3ULA24G9AHWVR31VJWSLB68	[I-D.ietf-mmusic-dtls-sdp]
a=rtcp-mux	[RFC5761]
a=rtcp-mux-only	[I-D.ietf-mmusic-mux-exclusive]
a=rtcp-rsize	[RFC5506]
a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-level	[RFC6464]
a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid	[I-D.ietf-mmusic-sdp-bundle-negotiation]
a=candidate:0 1 UDP 2122194687 192.0.2.4 61665 typ host	[I-D.ietf-mmusic-ice-sip-sdp]
a=candidate:1 1 UDP 1685987071 203.0.113.141 54609 typ srflx raddr 192.0.2.4 rport 61665	[I-D.ietf-mmusic-ice-sip-sdp]
a=end-of-candidates	[I-D.ietf-mmusic-trickle-ice]
**** Video m=line *******	*****************************
m=video 0 UDP/TLS/RTP/SAVPF 120	[RFC4566]
c=IN IP4 203.0.113.141	[RFC4566]
a=bundle-only	[I-D.ietf-mmusic-sdp-bundle-negotiation]
a=mid:video	[RFC5888]
a=msid:ma tb	Identifies MediaStream ID (ma) and MediaStreamTrack ID (tb)
a=sendrecv	[RFC3264]
a=rtpmap:120 VP8/90000	[RFC7741]
a=rtcp-fb:120 nack	[RFC4585]
a=rtcp-fb:120 nack pli	[RFC4585]
a=rtcp-fb:120 ccm fir	[RFC5104]
a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid	[I-D.ietf-mmusic-sdp-bundle-negotiation]
**** Application m=line *******	*****************************
m=application 0 UDP/DTLS/SCTP webrtc-datachannel	[I-D.ietf-rtcweb-data-channel]
c=IN IP4 203.0.113.141	[RFC4566]
a=bundle-only	[I-D.ietf-mmusic-sdp-bundle-negotiation]
a=mid:data	[RFC5888]
a=sctp-port:5000	[I-D.ietf-mmusic-sctp-sdp]
a=max-message-size:100000	[I-D.ietf-mmusic-sctp-sdp]
a=sendrecv	[RFC3264]

Table 18: 5.2.8 SDP Answer
Answer SDP Contents	RFC#/Notes
v=0	[RFC4566]
o=- 16833 0 IN IP4 0.0.0.0	[RFC4566] - Session Origin Information
s=-	[RFC4566]
t=0 0	[RFC4566]
a=group:BUNDLE audio video data	[I-D.ietf-mmusic-sdp-bundle-negotiation]
a=group:LS audio video	[RFC5888]
a=ice-options:trickle	[I-D.ietf-mmusic-trickle-ice]
a=ice-options:ice2	[RFC8445]
**** Audio m=line *******	*****************************
m=audio 49203 UDP/TLS/RTP/SAVPF 109	[RFC4566]
c=IN IP4 203.0.113.77	[RFC4566]
a=msid:ma ta	Identifies MediaStream ID (ma) and MediaStreamTrack ID (ta)
a=mid:audio	[RFC5888]
a=sendrecv	[RFC3264]
a=rtpmap:109 opus/48000/2	[RFC7587]
a=maxptime:120	[RFC4566]
a=ice-ufrag:c300d85b	[I-D.ietf-mmusic-ice-sip-sdp]
a=ice-pwd:de4e99bd291c325921d5d47efbabd9a2	[I-D.ietf-mmusic-ice-sip-sdp]
a=fingerprint:sha-256 6B:8B:F0:65:5F:78:E2:51:3B:AC:6F:F3:3F:46:1B:35:DC:B8:5F:64:1A:24:C2:43:F0:A1:58:D0:A1:2C:19:08	[RFC8122]
a=setup:active	[RFC5763]
a=tls-id:CJ6FF9ZZMJW7MDRJIR7XVIQM48GE1G31	[I-D.ietf-mmusic-dtls-sdp]
a=rtcp-mux	[RFC5761]
a=rtcp-mux-only	[I-D.ietf-mmusic-mux-exclusive]
a=rtcp-rsize	[RFC5506]
a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-level	[RFC6464]
a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid	[I-D.ietf-mmusic-sdp-bundle-negotiation]
a=candidate:0 1 UDP 2122194687 198.51.100.7 51556 typ host	[I-D.ietf-mmusic-ice-sip-sdp]
a=candidate:1 1 UDP 1685987071 203.0.113.77 49203 typ srflx raddr 198.51.100.7 rport 51556	[I-D.ietf-mmusic-ice-sip-sdp]
a=end-of-candidates	[I-D.ietf-mmusic-trickle-ice]
**** Video m=line *******	*****************************
m=video 0 UDP/TLS/RTP/SAVPF 120	[RFC4566]
c=IN IP4 203.0.113.77	[RFC4566]
a=bundle-only	[I-D.ietf-mmusic-sdp-bundle-negotiation]
a=mid:video	[RFC5888]
a=msid:ma tb	Identifies MediaStream ID (ma) and MediaStreamTrack ID (tb)
a=sendrecv	[RFC3264]
a=rtpmap:120 VP8/90000	[RFC7741]
a=rtcp-fb:120 nack	[RFC4585]
a=rtcp-fb:120 nack pli	[RFC4585]
a=rtcp-fb:120 ccm fir	[RFC5104]
a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid	[I-D.ietf-mmusic-sdp-bundle-negotiation]
**** Application m=line *******	*****************************
m=application 0 UDP/DTLS/SCTP webrtc-datachannel	[I-D.ietf-mmusic-sctp-sdp]
c=IN IP4 203.0.113.77	[RFC4566]
a=bundle-only	[I-D.ietf-mmusic-sdp-bundle-negotiation]
a=mid:data	[RFC5888]
a=sctp-port:5000	[I-D.ietf-mmusic-sctp-sdp]
a=max-message-size:100000	[I-D.ietf-mmusic-sctp-sdp]
a=sendrecv	[RFC3264]

5.2.9. Audioa andVideo Session with BUNDLE Unsupported

This use case illustrates SDP offer/answer exchange where the far-end (Bob) either doesn't support media bundling or doesn't want to group m=lines over a single 5-tuple.¶

This is indicated by dropping the "a=group:BUNDLE" line and BUNDLE RTP header extension in the answer SDP.¶

On successful offer/answer exchange, Alice and Bob each end up using unique 5-tuple for audio and video media streams respectively.¶



   Two-way Secure Audio and Video with BUNDLE Unsupported

Alice                                                 Bob
|                                                      |
|                                                      |
|     Alice offers BUNDLE support with unique address  |
|           for the audio and video m-line             |
|                                                      |
|                                                      |
|           offer(Audio:Opus Video:VP8)                |
|----------------------------------------------------->|
|                                                      |Bob
|                                                      |doesn't
|                                                      |support
|                                                      |BUNDLE
|           answer(Audio:Opus Video:VP8)               |
|<-----------------------------------------------------|
|                                                      |Bob uses
|                                                      |unique
|                                                      |addresses
|                                                      |across the
|                                                      |m=lines
|                                                      |
|    Two-way Call with Audio and Video on              |
|    different 5-tuples                                |
|......................................................|
|                                                      |
|                                                      |

Table 19: 5.2.9 SDP Offer w/BUNDLE
Offer SDP Contents	RFC#/Notes
v=0	[RFC4566]
o=- 20518 0 IN IP4 0.0.0.0	[RFC4566]
s=-	[RFC4566]
t=0 0	[RFC4566]
a=group:BUNDLE audio video	[I-D.ietf-mmusic-sdp-bundle-negotiation] Alice supports grouping of m=lines under BUNDLE semantics
a=group:LS audio video	[RFC5888]
a=ice-options:trickle	[I-D.ietf-mmusic-trickle-ice]
a=ice-options:ice2	[RFC8445]
**** Audio m=line *******	*****************************
m=audio 54609 UDP/TLS/RTP/SAVPF 109	[RFC4566]
c=IN IP4 203.0.113.141	[RFC4566]
a=mid:audio	[RFC5888] Audio m=line part of BUNDLE group with a unique port number
a=msid:ma ta	Identifies MediaStream ID (ma) and MediaStreamTrack ID (ta)
a=sendrecv	[RFC3264]
a=rtpmap:109 opus/48000/2	[RFC7587]
a=maxptime:120	[RFC4566]
a=ice-ufrag:074c6550	[I-D.ietf-mmusic-ice-sip-sdp]
a=ice-pwd:a28a397a4c3f31747d1ee3474af08a068	[I-D.ietf-mmusic-ice-sip-sdp]
a=fingerprint:sha-256 19:E2:1C:3B:4B:9F:81:E6:B8:5C:F4:A5:A8:D8:73:04:BB:05:2F:70:9F:04:A9:0E:05:E9:26:33:E8:70:88:A2	[RFC8122]
a=setup:actpass	[RFC5763] - Alice can act as DTLS client or server
a=tls-id:89J2LRATQ3ULA24G9AHWVR31VJWSLB68	[I-D.ietf-mmusic-dtls-sdp]
a=rtcp-mux	[RFC5761]
a=rtcp:55232 IN IP4 203.0.113.141	[RFC3605] - RTCP port different from RTP port
a=rtcp-rsize	[RFC5506]
a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-level	[RFC6464]
a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid	[I-D.ietf-mmusic-sdp-bundle-negotiation]
a=candidate:0 1 UDP 2122194687 192.0.2.4 61665 typ host	[I-D.ietf-mmusic-ice-sip-sdp]
a=candidate:1 1 UDP 1685987071 203.0.113.141 54609 typ srflx raddr 192.0.2.4 rport 61665	[I-D.ietf-mmusic-ice-sip-sdp]
a=candidate:0 2 UDP 2122194687 192.0.2.4 61666 typ host	[I-D.ietf-mmusic-ice-sip-sdp]
a=candidate:1 2 UDP 1685987071 203.0.113.141 55232 typ srflx raddr 192.0.2.4 rport 61666	[I-D.ietf-mmusic-ice-sip-sdp]
a=end-of-candidates	[I-D.ietf-mmusic-trickle-ice]
**** Video m=line *******	*****************************
m=video 54332 UDP/TLS/RTP/SAVPF 120	[RFC4566]
c=IN IP4 203.0.113.141	[RFC4566]
a=mid:video	[RFC5888] Video m=line part of the BUNDLE group with a unique port number
a=msid:ma tb	Identifies MediaStream ID (ma) and MediaStreamTrack ID (tb)
a=sendrecv	[RFC3264]
a=rtpmap:120 VP8/90000	[RFC7741]
a=ice-ufrag:7872093	[I-D.ietf-mmusic-ice-sip-sdp]
a=ice-pwd:ee3474af08a068a28a397a4c3f31747d1	[I-D.ietf-mmusic-ice-sip-sdp]
a=fingerprint:sha-256 19:E2:1C:3B:4B:9F:81:E6:B8:5C:F4:A5:A8:D8:73:04:BB:05:2F:70:9F:04:A9:0E:05:E9:26:33:E8:70:88:A2	[RFC8122]
a=setup:actpass	[RFC5763] - Alice can act as DTLS client or server
a=tls-id:UKA29UQLTF69OJW4WNPNUO2Y0GF1FJOZ	[I-D.ietf-mmusic-dtls-sdp]
a=rtcp-mux	[RFC5761]
a=rtcp:60052 IN IP4 203.0.113.141	[RFC3605]
a=rtcp-rsize	[RFC5506]
a=rtcp-fb:120 nack	[RFC4585]
a=rtcp-fb:120 nack pli	[RFC4585]
a=rtcp-fb:120 ccm fir	[RFC5104]
a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid	[I-D.ietf-mmusic-sdp-bundle-negotiation]
a=candidate:0 1 UDP 2122194687 192.0.2.4 71775 typ host	[I-D.ietf-mmusic-ice-sip-sdp]
a=candidate:1 1 UDP 1685987071 203.0.113.141 54332 typ srflx raddr 192.0.2.4 rport 71775	[I-D.ietf-mmusic-ice-sip-sdp]
a=candidate:0 2 UDP 2122194687 192.0.2.4 71776 typ host	[I-D.ietf-mmusic-ice-sip-sdp]
a=candidate:1 2 UDP 1685987071 203.0.113.141 60052 typ srflx raddr 192.0.2.4 rport 71776	[I-D.ietf-mmusic-ice-sip-sdp]
a=end-of-candidates	[I-D.ietf-mmusic-trickle-ice]

Table 20: 5.2.9 SDP Answer without BUNDLE
Answer SDP Contents	RFC#/Notes
v=0	[RFC4566]
o=- 16833 0 IN IP4 0.0.0.0	[RFC4566]
s=-	[RFC4566]
t=0 0	[RFC4566]
a=group:LS audio video	[RFC5888]
a=ice-options:trickle	[I-D.ietf-mmusic-trickle-ice]
a=ice-options:ice2	[RFC8445]
**** Audio m=line *******	*****************************
m=audio 53214 UDP/TLS/RTP/SAVPF 109	[RFC4566]
c=IN IP4 203.0.113.77	[RFC4566]
a=mid:audio	[RFC5888]
a=msid:ma ta	Identifies MediaStream ID (ma) and MediaStreamTrack ID (ta)
a=sendrecv	[RFC3264]
a=rtpmap:109 opus/48000/2	[RFC7587]
a=maxptime:120	[RFC4566]
a=ice-ufrag:c300d85b	[I-D.ietf-mmusic-ice-sip-sdp]
a=ice-pwd:de4e99bd291c325921d5d47efbabd9a2	[I-D.ietf-mmusic-ice-sip-sdp]
a=fingerprint:sha-256 6B:8B:F0:65:5F:78:E2:51:3B:AC:6F:F3:3F:46:1B:35:DC:B8:5F:64:1A:24:C2:43:F0:A1:58:D0:A1:2C:19:08	[RFC8122]
a=setup:active	[RFC5763] - Bob is the DTLS client
a=tls-id:CJ6FF9ZZMJW7MDRJIR7XVIQM48GE1G31	[I-D.ietf-mmusic-dtls-sdp]
a=rtcp-mux	[RFC5761]
a=rtcp-rsize	[RFC5506]
a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-level	[RFC6464]
a=candidate:0 1 UDP 2122194687 198.51.100.7 51556 typ host	[I-D.ietf-mmusic-ice-sip-sdp]
a=candidate:1 1 UDP 1685987071 203.0.113.77 53214 typ srflx raddr 198.51.100.7 rport 51556	[I-D.ietf-mmusic-ice-sip-sdp]
a=candidate:0 2 UDP 2122194687 198.51.100.7 51558 typ host	[I-D.ietf-mmusic-ice-sip-sdp]
a=candidate:1 2 UDP 1685987071 203.0.113.77 60065 typ srflx raddr 198.51.100.7 rport 51558	[I-D.ietf-mmusic-ice-sip-sdp]
**** Video m=line *******	*****************************
m=video 58679 UDP/TLS/RTP/SAVPF 120	[RFC4566]
c=IN IP4 203.0.113.77	[RFC4566]
a=mid:video	[RFC5888]
a=msid:ma tb	Identifies MediaStream ID (ma) and MediaStreamTrack ID (tb)
a=sendrecv	[RFC3264]
a=rtpmap:120 VP8/90000	[RFC7741]
a=ice-ufrag:85bC300	[I-D.ietf-mmusic-ice-sip-sdp]
a=ice-pwd:325921d5d47efbabd9a2de4e99bd291c	[I-D.ietf-mmusic-ice-sip-sdp]
a=fingerprint:sha-256 6B:8B:F0:65:5F:78:E2:51:3B:AC:6F:F3:3F:46:1B:35 :DC:B8:5F:64:1A:24:C2:43:F0:A1:58:D0:A1:2C:19:08	[RFC8122]
a=setup:active	[RFC5763] - Bob is the DTLS client
a=tls-id:9AIFS8AQ009IXF5D6QQUJ7P8BXPEZJ8G	[I-D.ietf-mmusic-dtls-sdp]
a=rtcp-mux	[RFC5761]
a=rtcp-rsize	[RFC5506]
a=rtcp-fb:120 nack	[RFC4585]
a=rtcp-fb:120 nack pli	[RFC4585]
a=rtcp-fb:120 ccm fir	[RFC5104]
a=candidate:0 1 UDP 2122194687 198.51.100.7 61556 typ host	[I-D.ietf-mmusic-ice-sip-sdp]
a=candidate:1 1 UDP 1685987071 203.0.113.77 58679 typ srflx raddr 198.51.100.7 rport 61556	[I-D.ietf-mmusic-ice-sip-sdp]
a=end-of-candidates	[I-D.ietf-mmusic-trickle-ice]

5.2.10. Audio, Video BUNDLED, but Data Not BUNDLED

This example showcases SDP for negotiating a session with audio, video, and the data streams between Alice and Bob with data stream not being part of the BUNDLE group. This is shown by assigning a unique port for the data media section and not adding the "mid" identification tag to the BUNDLE group.¶


       Audio, Video, with Data (Not in BUNDLE)

Alice                                                 Bob
|                                                      |
|                                                      |
|Alice wants to multiplex audio, video but not data    |
|                                                      |
|                                                      |
|  offer(Audio:Opus Video:VP8, Data(not in BUNDLE))    |
|----------------------------------------------------->|
|                                                      |
|                                                      |
|       answer(Audio:Opus Video:VP8, Data)             |
|<-----------------------------------------------------|
|                                                      |
|                                                      |
|Two-way Call with Audio, Video Multiplexed except data|
|......................................................|
|                                                      |

Table 21: 5.2.10 SDP Offer
Offer SDP Contents	RFC#/Notes
v=0	[RFC4566]
o=- 20518 0 IN IP4 0.0.0.0	[RFC4566]
s=-	[RFC4566]
t=0 0	[RFC4566]
a=group:BUNDLE audio video	[I-D.ietf-mmusic-sdp-bundle-negotiation] Alice wants to BUNDLE only audio and video media.
a=group:LS audio video	[RFC5888]
a=ice-options:trickle	[I-D.ietf-mmusic-trickle-ice]
a=ice-options:ice2	[RFC8445]
**** Audio m=line *******	*****************************
m=audio 54609 UDP/TLS/RTP/SAVPF 109	[RFC4566]
c=IN IP4 203.0.113.141	[RFC4566]
a=mid:audio	[RFC5888]
a=msid:ma ta	Identifies MediaStream ID (ma) and MediaStreamTrack ID (ta)
a=sendrecv	[RFC3264]
a=rtpmap:109 opus/48000/2	[RFC7587]
a=maxptime:120	[RFC4566]
a=ice-ufrag:074c6550	[I-D.ietf-mmusic-ice-sip-sdp]
a=ice-pwd:a28a397a4c3f31747d1ee3474af08a068	[I-D.ietf-mmusic-ice-sip-sdp]
a=fingerprint:sha-256 19:E2:1C:3B:4B:9F:81:E6:B8:5C:F4:A5:A8:D8:73:04:BB:05:2F:70:9F:04:A9:0E:05:E9:26:33:E8:70:88:A2	[RFC8122]
a=setup:actpass	[RFC5763]
a=tls-id:89J2LRATQ3ULA24G9AHWVR31VJWSLB68	[I-D.ietf-mmusic-dtls-sdp]
a=rtcp-mux	[RFC5761]
a=rtcp-mux-only	[I-D.ietf-mmusic-mux-exclusive]
a=rtcp-rsize	[RFC5506]
a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-level	[RFC6464]
a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid	[I-D.ietf-mmusic-sdp-bundle-negotiation]
a=candidate:0 1 UDP 2113667327 192.0.2.4 54609 typ host	[I-D.ietf-mmusic-ice-sip-sdp]
a=end-of-candidates	[I-D.ietf-mmusic-trickle-ice]
**** Video m=line *******	*****************************
m=video 0 UDP/TLS/RTP/SAVPF 120	[RFC4566]
c=IN IP4 203.0.113.141	[RFC4566]
a=bundle-only	[I-D.ietf-mmusic-sdp-bundle-negotiation]
a=mid:video	[RFC5888]
a=msid:ma tb	Identifies MediaStream ID (ma) and MediaStreamTrack ID (tb)
a=sendrecv	[RFC3264]
a=rtpmap:120 VP8/90000	[RFC7741]
a=rtcp-fb:120 nack	[RFC4585]
a=rtcp-fb:120 nack pli	[RFC4585]
a=rtcp-fb:120 ccm fir	[RFC5104]
a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid	[I-D.ietf-mmusic-sdp-bundle-negotiation]
**** Application m=line *******	*****************************
m=application 10000 UDP/DTLS/SCTP webrtc-datachannel	[I-D.ietf-rtcweb-data-channel]
c=IN IP4 203.0.113.141	[RFC4566]
a=mid:data	[RFC5888]
a=sctp-port:5000	[I-D.ietf-mmusic-sctp-sdp]
a=max-message-size:100000	[I-D.ietf-mmusic-sctp-sdp]
a=sendrecv	[RFC3264]
a=setup:actpass	[RFC5763]
a=tls-id:UKA29UQLTF69OJW4WNPNUO2Y0GF1FJOZ	[I-D.ietf-mmusic-dtls-sdp]
a=ice-ufrag:89819013	[I-D.ietf-mmusic-ice-sip-sdp]
a=ice-pwd:1747d1ee3474af08a068a28a397a4c3f3	[I-D.ietf-mmusic-ice-sip-sdp]
a=fingerprint:sha-256 29:E2:1C:3B:4B:9F:81:E6:B8:5C:F4:A5:A8:D8:73:04:BB:05:2F:70:9F:04:A9:0E:05:E9:26:33:E8:70:88:A2	[RFC8122]
a=candidate:0 1 UDP 2113667327 192.0.2.4 10000 typ host	[I-D.ietf-mmusic-ice-sip-sdp]
a=end-of-candidates	[I-D.ietf-mmusic-trickle-ice]

Table 22: 5.2.10 SDP Answer
Answer SDP Contents	RFC#/Notes
v=0	[RFC4566]
o=- 16833 0 IN IP4 0.0.0.0	[RFC4566] - Session Origin Information
s=-	[RFC4566]
t=0 0	[RFC4566]
a=group:BUNDLE audio video	[I-D.ietf-mmusic-sdp-bundle-negotiation]
a=group:LS audio video	[RFC5888]
a=ice-options:trickle	[I-D.ietf-mmusic-trickle-ice]
a=ice-options:ice2	[RFC8445]
**** Audio m=line *******	*****************************
m=audio 49203 UDP/TLS/RTP/SAVPF 109	[RFC4566]
c=IN IP4 203.0.113.77	[RFC4566]
a=mid:audio	[RFC5888]
a=msid:ma ta	Identifies MediaStream ID (ma) and MediaStreamTrack ID (ta)
a=sendrecv	[RFC3264]
a=rtpmap:109 opus/48000/2	[RFC7587]
a=maxptime:120	[RFC4566]
a=ice-ufrag:c300d85b	[I-D.ietf-mmusic-ice-sip-sdp]
a=ice-pwd:de4e99bd291c325921d5d47efbabd9a2	[I-D.ietf-mmusic-ice-sip-sdp]
a=fingerprint:sha-256 6B:8B:F0:65:5F:78:E2:51:3B:AC:6F:F3:3F:46:1B:35:DC:B8:5F:64:1A:24:C2:43:F0:A1:58:D0:A1:2C:19:08	[RFC8122]
a=setup:active	[RFC5763]
a=tls-id:CJ6FF9ZZMJW7MDRJIR7XVIQM48GE1G31	[I-D.ietf-mmusic-dtls-sdp]
a=rtcp-mux	[RFC5761]
a=rtcp-mux-only	[I-D.ietf-mmusic-mux-exclusive]
a=rtcp-rsize	[RFC5506]
a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-level	[RFC6464]
a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid	[I-D.ietf-mmusic-sdp-bundle-negotiation]
a=candidate:0 1 UDP 2113667327 198.51.100.7 49203 typ host	[I-D.ietf-mmusic-ice-sip-sdp]
a=end-of-candidates	[I-D.ietf-mmusic-trickle-ice]
**** Video m=line *******	*****************************
m=video 0 UDP/TLS/RTP/SAVPF 120	[RFC4566]
c=IN IP4 203.0.113.77	[RFC4566]
a=bundle-only	[I-D.ietf-mmusic-sdp-bundle-negotiation]
a=mid:video	[RFC5888]
a=msid:ma tb	Identifies MediaStream ID (ma) and MediaStreamTrack ID (tb)
a=sendrecv	[RFC3264]
a=rtpmap:120 VP8/90000	[RFC7741]
a=rtcp-fb:120 nack	[RFC4585]
a=rtcp-fb:120 nack pli	[RFC4585]
a=rtcp-fb:120 ccm fir	[RFC5104]
a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid	[I-D.ietf-mmusic-sdp-bundle-negotiation]
**** Application m=line *******	*****************************
m=application 20000 UDP/DTLS/SCTP webrtc-datachannel	[I-D.ietf-mmusic-sctp-sdp]
c=IN IP4 203.0.113.77	[RFC4566]
a=mid:data	[RFC5888]
a=sctp-port:5000	[I-D.ietf-mmusic-sctp-sdp]
a=max-message-size:100000	[I-D.ietf-mmusic-sctp-sdp]
a=setup:active	[RFC5763]
a=tls-id:9AIFS8AQ009IXF5D6QQUJ7P8BXPEZJ8G	[I-D.ietf-mmusic-dtls-sdp]
a=sendrecv	[RFC3264]
a=ice-ufrag:991Ca2a5e	[I-D.ietf-mmusic-ice-sip-sdp]
a=ice-pwd:921d5d47efbabd9a2de4e99bd291c325	[I-D.ietf-mmusic-ice-sip-sdp]
a=fingerprint:sha-256 7B:8B:F0:65:5F:78:E2:51:3B:AC:6F:F3:3F:46:1B:35:DC:B8:5F:64:1A:24:C2:43:F0:A1:58:D0:A1:2C:19:08	[RFC8122]
a=candidate:0 1 UDP 2113667327 198.51.100.7 20000 typ host	[I-D.ietf-mmusic-ice-sip-sdp]
a=end-of-candidates	[I-D.ietf-mmusic-trickle-ice]

5.2.11. Audio Only, Add Video to BUNDLE

This example involves 2 offer/answer exchanges. The first one is used to negotiate and set up BUNDLE support for audio-only session followed by an updated offer/answer exchange to add video stream to the ongoing session. Also the newly added video stream is BUNDLED with the audio stream.¶



         Audio, Add Video and BUNDLE

Alice                                                 Bob
|                                                      |
|                                                      |
|        Alice indicates support for BUNDLE            |
|                                                      |
|                offer(Audio:Opus)                     |
|----------------------------------------------------->|
|                                                      |Bob
|                                                      |supports
|                                                      |BUNDLE
|                answer(Audio:Opus)                    |
|<-----------------------------------------------------|
|                                                      |Alice adds
|                                                      |video stream
|        Updated offer(Audio:Opus, Video:VP8)          |to BUNDLE
|----------------------------------------------------->|
|                                                      |
|                                                      |Bob accepts
|        Updated answer(Audio:Opus, Video:VP8)         |
|<-----------------------------------------------------|
|                                                      |
|   Two-way Call with Audio and Video Multiplexed      |
|......................................................|
|                                                      |
|                                                      |

Table 23: 5.2.11 SDP Offer
Offer SDP Contents	RFC#/Notes
v=0	[RFC4566]
o=- 20518 0 IN IP4 0.0.0.0	[RFC4566]
s=-	[RFC4566]
t=0 0	[RFC4566]
a=group:BUNDLE audio	[I-D.ietf-mmusic-sdp-bundle-negotiation] Alice adds audio m=line to the BUNDLE group
a=ice-options:trickle	[I-D.ietf-mmusic-trickle-ice]
a=ice-options:ice2	[RFC8445]
**** Audio m=line *******	*****************************
m=audio 54609 UDP/TLS/RTP/SAVPF 109	[RFC4566]
c=IN IP4 203.0.113.141	[RFC4566]
a=mid:audio	[RFC5888]
a=msid:ma ta	Identifies MediaStream ID (ma) and MediaStreamTrack ID (ta)
a=sendrecv	[RFC3264]
a=rtpmap:109 opus/48000/2	[RFC7587]
a=maxptime:120	[RFC4566]
a=ice-ufrag:074c6550	[I-D.ietf-mmusic-ice-sip-sdp]
a=ice-pwd:a28a397a4c3f31747d1ee3474af08a068	[I-D.ietf-mmusic-ice-sip-sdp]
a=fingerprint:sha-256 19:E2:1C:3B:4B:9F:81:E6:B8:5C:F4:A5:A8:D8:73:04:BB:05:2F:70:9F:04:A9:0E:05:E9:26:33:E8:70:88:A2	[RFC8122]
a=setup:actpass	[RFC5763]
a=tls-id:89J2LRATQ3ULA24G9AHWVR31VJWSLB68	[I-D.ietf-mmusic-dtls-sdp]
a=rtcp-mux	[RFC5761]
a=rtcp-mux-only	[I-D.ietf-mmusic-mux-exclusive]
a=rtcp-rsize	[RFC5506]
a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-level	[RFC6464]
a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid	[I-D.ietf-mmusic-sdp-bundle-negotiation]
a=candidate:0 1 UDP 2113667327 192.0.2.4 61665 typ host	[I-D.ietf-mmusic-ice-sip-sdp]
a=candidate:1 1 UDP 694302207 203.0.113.141 54609 typ srflx raddr 192.0.2.4 rport 61665	[I-D.ietf-mmusic-ice-sip-sdp]
a=end-of-candidates	[I-D.ietf-mmusic-trickle-ice]

Table 24: 5.2.10 SDP Answer
Answer SDP Contents	RFC#/Notes
v=0	[RFC4566]
o=- 16833 0 IN IP4 0.0.0.0	[RFC4566] - Session Origin Information
s=-	[RFC4566]
t=0 0	[RFC4566]
a=group:BUNDLE audio	[I-D.ietf-mmusic-sdp-bundle-negotiation]
a=ice-options:trickle	[I-D.ietf-mmusic-trickle-ice]
a=ice-options:ice2	[RFC8445]
**** Audio m=line *******	*****************************
m=audio 49203 UDP/TLS/RTP/SAVPF 109	[RFC4566]
c=IN IP4 203.0.113.77	[RFC4566]
a=mid:audio	[RFC5888]
a=msid:ma ta	Identifies MediaStream ID (ma) and MediaStreamTrack ID (ta)
a=sendrecv	[RFC3264]
a=rtpmap:109 opus/48000/2	[RFC7587]
a=maxptime:120	[RFC4566]
a=ice-ufrag:c300d85b	[I-D.ietf-mmusic-ice-sip-sdp]
a=ice-pwd:de4e99bd291c325921d5d47efbabd9a2	[I-D.ietf-mmusic-ice-sip-sdp]
a=fingerprint:sha-256 6B:8B:F0:65:5F:78:E2:51:3B:AC:6F:F3:3F:46:1B:35:DC:B8:5F:64:1A:24:C2:43:F0:A1:58:D0:A1:2C:19:08	[RFC8122]
a=setup:active	[RFC5763]
a=tls-id:CJ6FF9ZZMJW7MDRJIR7XVIQM48GE1G31	[I-D.ietf-mmusic-dtls-sdp]
a=rtcp-mux	[RFC5761]
a=rtcp-mux-only	[I-D.ietf-mmusic-mux-exclusive]
a=rtcp-rsize	[RFC5506]
a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-level	[RFC6464]
a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid	[I-D.ietf-mmusic-sdp-bundle-negotiation]
a=candidate:0 1 UDP 2113667327 198.51.100.7 51556 typ host	[I-D.ietf-mmusic-ice-sip-sdp]
a=candidate:1 1 UDP 1694302207 203.0.113.77 49203 typ srflx raddr 198.51.100.7 rport 51556	[I-D.ietf-mmusic-ice-sip-sdp]
a=end-of-candidates	[I-D.ietf-mmusic-trickle-ice]

Table 25: 5.2.11 SDP Updated Offer
Updated Offer SDP Contents	RFC#/Notes
v=0	[RFC4566]
o=- 20518 1 IN IP4 0.0.0.0	Version number incremented [RFC4566]
s=-	[RFC4566]
t=0 0	[RFC4566]
a=group:BUNDLE audio video	[I-D.ietf-mmusic-sdp-bundle-negotiation]
a=group:LS audio video	[RFC5888]
a=ice-options:trickle	[I-D.ietf-mmusic-trickle-ice]
a=ice-options:ice2	[RFC8445]
**** Audio m=line *******	*****************************
m=audio 54609 UDP/TLS/RTP/SAVPF 109	[RFC4566]
c=IN IP4 203.0.113.141	[RFC4566]
a=mid:audio	[RFC5888]
a=msid:ma ta	Identifies MediaStream ID (ma) and MediaStreamTrack ID (ta)
a=sendrecv	[RFC3264]
a=rtpmap:109 opus/48000/2	[RFC7587]
a=maxptime:120	[RFC4566]
a=ice-ufrag:074c6550	[I-D.ietf-mmusic-ice-sip-sdp]
a=ice-pwd:a28a397a4c3f31747d1ee3474af08a068	[I-D.ietf-mmusic-ice-sip-sdp]
a=fingerprint:sha-256 19:E2:1C:3B:4B:9F:81:E6:B8:5C:F4:A5:A8:D8:73:04:BB:05:2F:70:9F:04:A9:0E:05:E9:26:33:E8:70:88:A2	[RFC8122]
a=setup:actpass	[RFC5763]
a=tls-id:89J2LRATQ3ULA24G9AHWVR31VJWSLB68	[I-D.ietf-mmusic-dtls-sdp]Alice wants to use the same DTLS association
a=rtcp-mux	[RFC5761]
a=rtcp-mux-only	[I-D.ietf-mmusic-mux-exclusive]
a=rtcp-rsize	[RFC5506]
a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-level	[RFC6464]
a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid	[I-D.ietf-mmusic-sdp-bundle-negotiation]
a=candidate:0 1 UDP 2113667327 192.0.2.4 61665 typ host	[I-D.ietf-mmusic-ice-sip-sdp]
a=candidate:1 1 UDP 694302207 203.0.113.141 54609 typ srflx raddr 192.0.2.4 rport 61665	[I-D.ietf-mmusic-ice-sip-sdp]
a=end-of-candidates	[I-D.ietf-mmusic-trickle-ice]
**** Video m=line *******	*****************************
m=video 0 UDP/TLS/RTP/SAVPF 120	[RFC4566]
c=IN IP4 203.0.113.141	[RFC4566]
a=bundle-only	[I-D.ietf-mmusic-sdp-bundle-negotiation]
a=mid:video	[RFC5888]
a=msid:ma tb	Identifies MediaStream ID (ma) and MediaStreamTrack ID (tb)
a=sendrecv	[RFC3264]
a=rtpmap:120 VP8/90000	[RFC7741]
a=rtcp-fb:120 nack	[RFC4585]
a=rtcp-fb:120 nack pli	[RFC4585]
a=rtcp-fb:120 ccm fir	[RFC5104]
a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid	[I-D.ietf-mmusic-sdp-bundle-negotiation]

Table 26: 5.2.11 SDP Updated Answer
Updated Answer SDP Contents	RFC#/Notes
v=0	[RFC4566] Version number incremented
o=- 16833 1 IN IP4 0.0.0.0	[RFC4566] - Session Origin Information
s=-	[RFC4566]
t=0 0	[RFC4566]
a=group:BUNDLE audio video	[I-D.ietf-mmusic-sdp-bundle-negotiation]
a=group:LS audio video	[RFC5888]
a=ice-options:trickle	[I-D.ietf-mmusic-trickle-ice]
a=ice-options:ice2	[RFC8445]
**** Audio m=line *******	*****************************
m=audio 49203 UDP/TLS/RTP/SAVPF 109	[RFC4566]
c=IN IP4 203.0.113.77	[RFC4566]
a=mid:audio	[RFC5888]
a=msid:ma ta	Identifies MediaStream ID (ma) and MediaStreamTrack ID (ta)
a=sendrecv	[RFC3264]
a=rtpmap:109 opus/48000/2	[RFC7587]
a=maxptime:120	[RFC4566]
a=ice-ufrag:c300d85b	[I-D.ietf-mmusic-ice-sip-sdp]
a=ice-pwd:de4e99bd291c325921d5d47efbabd9a2	[I-D.ietf-mmusic-ice-sip-sdp]
a=fingerprint:sha-256 6B:8B:F0:65:5F:78:E2:51:3B:AC:6F:F3:3F:46:1B:35:DC:B8:5F:64:1A:24:C2:43:F0:A1:58:D0:A1:2C:19:08	[RFC8122]
a=setup:active	[RFC5763]
a=tls-id:CJ6FF9ZZMJW7MDRJIR7XVIQM48GE1G31	[I-D.ietf-mmusic-dtls-sdp] - Bob agrees to use the same DTLS association
a=rtcp-mux	[RFC5761]
a=rtcp-mux-only	[I-D.ietf-mmusic-mux-exclusive]
a=rtcp-rsize	[RFC5506]
a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-level	[RFC6464]
a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid	[I-D.ietf-mmusic-sdp-bundle-negotiation]
a=candidate:0 1 UDP 2113667327 198.51.100.7 51556 typ host	[I-D.ietf-mmusic-ice-sip-sdp]
a=candidate:1 1 UDP 1694302207 203.0.113.77 49203 typ srflx raddr 198.51.100.7 rport 51556	[I-D.ietf-mmusic-ice-sip-sdp]
a=end-of-candidates	[I-D.ietf-mmusic-trickle-ice]
**** Video m=line *******	*****************************
m=video 0 UDP/TLS/RTP/SAVPF 120	[RFC4566]
c=IN IP4 203.0.113.77	[RFC4566]
a=bundle-only	[I-D.ietf-mmusic-sdp-bundle-negotiation]
a=mid:video	[RFC5888]
a=msid:ma tb	Identifies MediaStream ID (ma) and MediaStreamTrack ID (tb)
a=sendrecv	[RFC3264]
a=rtpmap:120 VP8/90000	[RFC7741]
a=rtcp-fb:120 nack	[RFC4585]
a=rtcp-fb:120 nack pli	[RFC4585]
a=rtcp-fb:120 ccm fir	[RFC5104]
a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid	[I-D.ietf-mmusic-sdp-bundle-negotiation]

5.3. MultiResolution, RTX, FEC Examples

This section provides examples related to multi-source, multi-stream negotiation such as layered coding and simulcast. Further included are a few examples that cover techniques to deal with providing robustness against transmission errors such as FEC and RTX. Also, mechanisms such as FEC and RTX could be envisioned in the above basic scenarios as well.¶

5.3.1. Send-only Simulcast Session with 2 Cameras and 2 Encodings per Camera

The SDP example below shows an offer/answer exchange with one audio and two video sources (say 2 video cameras). Each of the video sources can be sent at two different resolutions.¶

One video source corresponds to VP8 encoding, while the other corresponds to H.264 encoding.¶

The [I-D.ietf-mmusic-rid] framework is used to further constrain the media format encodings and map the payload types (PT) to the 'rid' identifiers.¶

The [I-D.ietf-mmusic-sdp-simulcast] framework identifies the simulcast streams via their 'rid' identifiers.¶

The bundle-only attribute is used for the video sources in the offer to ensure enabling video sources solely in the context of BUNDLE alone.¶

The BUNDLE grouping framework enables multiplexing of all 5 Source RTP Streams (1 audio stream + 4 video streams) over a single RTP session.¶

Also, the audio and one video source RTP stream form a lip sync group while the other video source RTP stream represents non-interactive media data.¶


       One-way Successful Simulcast w/BUNDLE

Alice                                            Bob
|                                                 |
|                                                 |
|     Alice offers 2 send-only video sources      |
|     with 2 simulcast encodings per source       |
|           and bundle-only for video             |
|                                                 |
|                                                 |
|   offer(Audio:Opus,Video1:VP8,Video2:H.264)     |
|------------------------------------------------>|
|                                                 |
|                                                 |
|    answer(Audio:Opus Video1:VP8,Video2:H.264)   |
|<------------------------------------------------|
|                                                 |
|One-way 1 Opus, 2 H.264, and 2 VP8 video streams,|
| all multiplexed                                 |
|.................................................|
|                                                 |
|                                                 |

Table 27: 5.3.1 SDP Offer
Offer SDP Contents	RFC#/Notes
v=0	[RFC4566]
o=- 20519 0 IN IP4 0.0.0.0	[RFC4566]
s=-	[RFC4566]
t=0 0	[RFC4566]
a=group:BUNDLE m0 m1 m2	[I-D.ietf-mmusic-sdp-bundle-negotiation] Alice supports grouping of m=lines under BUNDLE semantics
a=group:LS m0 m1	[RFC5888]
a=ice-options:trickle	[I-D.ietf-mmusic-trickle-ice]
a=ice-options:ice2	[RFC8445]
**** Audio m=line *******	*****************************
m=audio 54609 UDP/TLS/RTP/SAVPF 109	[RFC4566]
c=IN IP4 203.0.113.141	[RFC4566]
a=mid:m0	[RFC5888]
a=msid:ma ta	Identifies MediaStream ID (ma) and MediaStreamTrack ID (ta)
a=sendonly	[RFC3264]
a=rtpmap:109 opus/48000/2	[RFC7587]
a=maxptime:120	[RFC4566]
a=ice-ufrag:074c6550	[I-D.ietf-mmusic-ice-sip-sdp]
a=ice-pwd:a28a397a4c3f31747d1ee3474af08a068	[I-D.ietf-mmusic-ice-sip-sdp]
a=fingerprint:sha-256 19:E2:1C:3B:4B:9F:81:E6:B8:5C:F4:A5:A8:D8:73:04:BB:05:2F:70:9F:04:A9:0E:05:E9:26:33:E8:70:88:A2	[RFC8122]
a=setup:actpass	[RFC5763]
a=tls-id:89J2LRATQ3ULA24G9AHWVR31VJWSLB68	[I-D.ietf-mmusic-dtls-sdp]
a=rtcp-mux	[RFC5761]
a=rtcp-rsize	[RFC5506]
a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-level	[RFC6464]
a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid	[I-D.ietf-mmusic-sdp-bundle-negotiation]
a=candidate:0 1 UDP 2113667327 192.0.2.4 61665 typ host	[I-D.ietf-mmusic-ice-sip-sdp]
a=candidate:1 1 UDP 694302207 203.0.113.141 54609 typ srflx raddr 192.0.2.4 rport 61665	[I-D.ietf-mmusic-ice-sip-sdp]
a=end-of-candidates	[I-D.ietf-mmusic-trickle-ice]
**** Video-1 m=line *******	*****************************
m=video 0 UDP/TLS/RTP/SAVPF 98 100	bundle-only video line with port number set to zero
c=IN IP4 203.0.113.141	[RFC4566]
a=bundle-only	[I-D.ietf-mmusic-sdp-bundle-negotiation]
a=mid:m1	[RFC5888] Video m=line part of BUNDLE group
a=msid:ma tb	Identifies MediaStream ID (ma) and MediaStreamTrack ID (tb)
a=sendonly	[RFC3264] - Send-only video stream
a=rtpmap:98 VP8/90000	[RFC7741]
a=fmtp:98 max-fr=30	[RFC4566]
a=rtpmap:100 VP8/90000	[RFC7741]
a=fmtp:100 max-fr=15	[RFC4566]
a=rtcp-fb:* nack	[RFC4585]
a=rtcp-fb:* nack pli	[RFC4585]
a=rtcp-fb:* ccm fir	[RFC5104]
a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid	[I-D.ietf-mmusic-sdp-bundle-negotiation]
a=extmap:3 urn:ietf:params:rtp-hdrext:sdes:rtp-stream-id	[I-D.ietf-avtext-rid]
a=rid:1 send pt=98;max-width=1280;max-height=720	[I-D.ietf-mmusic-rid] 1:1 rid mapping to payload type and specify resolution constraints
a=rid:2 send pt=100;max-width=640;max-height=480	[I-D.ietf-mmusic-rid] 1:1 rid mapping to payload type and specify resolution constraints
a=simulcast:send 1;~2	[I-D.ietf-mmusic-sdp-simulcast] Alice can send 2 resolutions identified by the 'rid' identifiers Also, the second stream is initially paused.
**** Video-2 m=line *******	*****************************
m=video 0 UDP/TLS/RTP/SAVPF 101 102	bundle-only video line with port number set to zero
c=IN IP4 203.0.113.141	[RFC4566]
a=bundle-only	[I-D.ietf-mmusic-sdp-bundle-negotiation]
a=mid:m2	[RFC5888] Video m=line part of BUNDLE group
a=msid:ma tc	Identifies MediaStream ID (ma) and MediaStreamTrack ID (tc)
a=sendonly	[RFC3264] - Send only video stream
a=rtpmap:101 H264/90000	[RFC6184]
a=rtpmap:102 H264/90000	[RFC6184]
a=fmtp:101 profile-level-id=42401f;packetization-mode=0	[RFC6184]Camera-2,Encoding-1
a=fmtp:102 profile-level-id=42401f;packetization-mode=1	[RFC6184]Camera-2,Encoding-2
a=rtcp-fb:* nack	[RFC4585]
a=rtcp-fb:* nack pli	[RFC4585]
a=rtcp-fb:* ccm fir	[RFC5104]
a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid	[I-D.ietf-mmusic-sdp-bundle-negotiation]
a=extmap:3 urn:ietf:params:rtp-hdrext:sdes:rtp-stream-id	[I-D.ietf-avtext-rid]
a=rid:3 send pt=101;max-width=1280;max-height=720;max-fr=30	[I-D.ietf-mmusic-rid] 1:1 rid mapping to payload type and specify resolution constraints
a=rid:4 send pt=102;max-width=640;max-height=360;max-fr=15	[I-D.ietf-mmusic-rid] 1:1 rid mapping to payload type and specify resolution constraints
a=simulcast:send 3;4	[I-D.ietf-mmusic-sdp-simulcast] Alice can send 2 resolutions identified by the 'rid' identifiers

Table 28: 5.3.1 SDP Answer
Answer SDP Contents	RFC#/Notes
v=0	[RFC4566]
o=- 20519 0 IN IP4 0.0.0.0	[RFC4566]
s=-	[RFC4566]
t=0 0	[RFC4566]
a=group:BUNDLE m0 m1 m2	[I-D.ietf-mmusic-sdp-bundle-negotiation] Alice supports grouping of m=lines under BUNDLE semantics
a=group:LS m0 m1	[RFC5888]
a=ice-options:trickle	[I-D.ietf-mmusic-trickle-ice]
a=ice-options:ice2	[RFC8445]
**** Audio m=line *******	*****************************
m=audio 49203 UDP/TLS/RTP/SAVPF 109	[RFC4566]
c=IN IP4 203.0.113.77	[RFC4566]
a=mid:m0	[RFC5888]
a=msid:ma ta	Identifies MediaStream ID (ma) and MediaStreamTrack ID (ta)
a=recvonly	[RFC3264]
a=rtpmap:109 opus/48000/2	[RFC7587]
a=maxptime:120	[RFC4566]
a=ice-ufrag:c300d85b	[I-D.ietf-mmusic-ice-sip-sdp]
a=ice-pwd:de4e99bd291c325921d5d47efbabd9a2	[I-D.ietf-mmusic-ice-sip-sdp]
a=fingerprint:sha-256 6B:8B:F0:65:5F:78:E2:51:3B:AC:6F:F3:3F:46:1B:35:DC:B8:5F:64:1A:24:C2:43:F0:A1:58:D0:A1:2C:19:08	[RFC8122]
a=setup:active	[RFC5763]
a=tls-id:CJ6FF9ZZMJW7MDRJIR7XVIQM48GE1G31	[I-D.ietf-mmusic-dtls-sdp]
a=rtcp-mux	[RFC5761]
a=rtcp-rsize	[RFC5506]
a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-level	[RFC6464]
a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid	[I-D.ietf-mmusic-sdp-bundle-negotiation]
a=candidate:0 1 UDP 2113667327 198.51.100.7 61665 typ host	[I-D.ietf-mmusic-ice-sip-sdp]
a=candidate:1 1 UDP 694302207 203.0.113.77 49203 typ srflx raddr 198.51.100.7 rport 61665	[I-D.ietf-mmusic-ice-sip-sdp]
a=end-of-candidates	[I-D.ietf-mmusic-trickle-ice]
**** Video-1 m=line *******	*****************************
m=video 0 UDP/TLS/RTP/SAVPF 98 100	BUNDLE accepted
c=IN IP4 203.0.113.77	[RFC4566]
a=bundle-only	[I-D.ietf-mmusic-sdp-bundle-negotiation]
a=mid:m1	[RFC5888] Video m=line part of BUNDLE group
a=msid:ma tb	Identifies MediaStream ID (ma) and MediaStreamTrack ID (tb)
a=recvonly	[RFC3264] - receive only video stream
a=rtpmap:98 VP8/90000	[RFC7741]
a=rtpmap:100 VP8/90000	[RFC7741]
a=fmtp:98 max-fr=30	[RFC4566]
a=fmtp:100 max-fr=15	[RFC4566]
a=rtcp-fb:* nack	[RFC4585]
a=rtcp-fb:* nack pli	[RFC4585]
a=rtcp-fb:* ccm fir	[RFC5104]
a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid	[I-D.ietf-mmusic-sdp-bundle-negotiation]
a=extmap:3 urn:ietf:params:rtp-hdrext:sdes:rtp-stream-id	[I-D.ietf-avtext-rid]
a=rid:1 recv pt=98;max-width=1280;max-height=720	[I-D.ietf-mmusic-rid] Bob accepts the offered payload format constraints
a=rid:2 recv pt=100;max-width=640;max-height=480	[I-D.ietf-mmusic-rid] Bob accepts the offered payload format constraints
a=simulcast:recv 1;2	[I-D.ietf-mmusic-sdp-simulcast] Bob accepts the offered simulcast streams and removes the paused state of stream with 'rid' value 2.
**** Video-2 m=line *******	*****************************
m=video 0 UDP/TLS/RTP/SAVPF 101 102	BUNDLE accepted
c=IN IP4 203.0.113.77	[RFC4566]
a=bundle-only	[I-D.ietf-mmusic-sdp-bundle-negotiation]
a=mid:m2	[RFC5888] Video m=line part of BUNDLE group
a=msid:ma tc	Identifies MediaStream ID (ma) and MediaStreamTrack ID (tc)
a=recvonly	[RFC3264]
a=rtpmap:101 H264/90000	[RFC6184]
a=rtpmap:102 H264/90000	[RFC6184]
a=fmtp:101 profile-level-id=42401f;packetization-mode=1	[RFC6184]
a=fmtp:102 profile-level-id=42401f;packetization-mode=1	[RFC6184]
a=rtcp-fb:* nack	[RFC4585]
a=rtcp-fb:* nack pli	[RFC4585]
a=rtcp-fb:* ccm fir	[RFC5104]
a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid	[I-D.ietf-mmusic-sdp-bundle-negotiation]
a=extmap:3 urn:ietf:params:rtp-hdrext:sdes:rtp-stream-id	[I-D.ietf-avtext-rid]
a=rid:3 recv pt=101;max-width=1280;max-height=720;max-fr=30	[I-D.ietf-mmusic-rid] Bob accepts the offered payload format constraints
a=rid:4 recv pt=102;max-width=640;max-height=360;max-fr=15	[I-D.ietf-mmusic-rid] Bob accepts the offered payload format constraints
a=simulcast:recv 3;4	[I-D.ietf-mmusic-sdp-simulcast] Bob accepts the offered simulcast streams.

5.3.2. Successful SVC Video Session

This section shows an SDP offer/answer for a session with an audio and a single video source. The video source is being encoded both as non-scalable and scalable H.264-SVC RTP streams (in the SST mode).¶

The answerer picks the payload type corresponding to scalable encoding.¶


        SVC Session - 3 Layers w/BUNDLE

Alice                                            Bob
|                                                 |
|                                                 |
|      Alice offers a send-only video stream      |
|      with non-scalable and scalable encodings.  |
|                                                 |
|                                                 |
|  offer(Audio:Opus, Video:H.264/H.264-SVC)       |
|------------------------------------------------>|
|                                                 |
|                                                 |Bob accepts Alice's
|                                                 |offered codec
|                                                 |operation points
|                                                 |for scalable encoding
|                                                 |
|  answer(Audio:Opus, Video:H.264-SVC)            |
|<------------------------------------------------|
|                                                 |
| One-way Opus, H.264-SVC video streams           |
|.................................................|
|                                                 |
|                                                 |

Table 29: 5.3.2 SDP Offer with SVC
Offer SDP Contents	RFC#/Notes
v=0	[RFC4566]
o=- 20519 0 IN IP4 0.0.0.0	[RFC4566]
s=-	[RFC4566]
t=0 0	[RFC4566]
a=group:BUNDLE m0 m1	[I-D.ietf-mmusic-sdp-bundle-negotiation] Alice supports grouping of m=lines under BUNDLE semantics
a=group:LS m0 m1	[RFC5888]
a=ice-options:trickle	[I-D.ietf-mmusic-trickle-ice]
a=ice-options:ice2	[RFC8445]
**** Audio m=line *******	*****************************
m=audio 54609 UDP/TLS/RTP/SAVPF 109	[RFC4566]
c=IN IP4 203.0.113.141	[RFC4566]
a=mid:m0	[RFC5888] Audio m=line part of BUNDLE group with a unique port number
a=msid:ma ta	Identifies MediaStream ID (ma) and MediaStreamTrack ID (ta)
a=sendonly	[RFC3264]
a=rtpmap:109 opus/48000/2	[RFC7587]
a=maxptime:120	[RFC4566]
a=ice-ufrag:074c6550	[I-D.ietf-mmusic-ice-sip-sdp]
a=ice-pwd:a28a397a4c3f31747d1ee3474af08a068	[I-D.ietf-mmusic-ice-sip-sdp]
a=fingerprint:sha-256 19:E2:1C:3B:4B:9F:81:E6:B8:5C:F4:A5:A8:D8:73:04:BB:05:2F:70:9F:04:A9:0E:05:E9:26:33:E8:70:88:A2	[RFC8122]
a=setup:actpass	[RFC5763]
a=tls-id:89J2LRATQ3ULA24G9AHWVR31VJWSLB68	[I-D.ietf-mmusic-dtls-sdp]
a=rtcp-mux	[RFC5761]
a=rtcp-rsize	[RFC5506]
a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-level	[RFC6464]
a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid	[I-D.ietf-mmusic-sdp-bundle-negotiation]
a=candidate:0 1 UDP 2113667327 192.0.2.4 61665 typ host	[I-D.ietf-mmusic-ice-sip-sdp]
a=candidate:1 1 UDP 694302207 203.0.113.141 54609 typ srflx raddr 192.0.2.4 rport 61665	[I-D.ietf-mmusic-ice-sip-sdp]
a=end-of-candidates	[I-D.ietf-mmusic-trickle-ice]
**** Video m=line *******	*****************************
m=video 0 UDP/TLS/RTP/SAVPF 96 100	bundle-only video line with port number set to zero
c=IN IP4 203.0.113.141	[RFC4566]
a=bundle-only	[I-D.ietf-mmusic-sdp-bundle-negotiation]
a=mid:m1	[RFC5888] Video m=line part of BUNDLE group
a=msid:ma tb	Identifies MediaStream ID (ma) and MediaStreamTrack ID (tb)
a=sendonly	[RFC3264] - Send only video stream
a=rtpmap:96 H264/90000	[RFC6184]
a=fmtp:96 profile-level-id=4d0028; packetization-mode=1;max-fs=8040	[RFC6184]H.264 Non Scalable
a=rtpmap:100 H264-SVC/90000	[RFC6190]
a=fmtp:100 profile-level-id=53001f;packetization-mode=0	[RFC6190] H.264 Scalable Encoding
a=rtcp-fb:* nack	[RFC4585]
a=rtcp-fb:* nack pli	[RFC4585]
a=rtcp-fb:* ccm fir	[RFC5104]
a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid	[I-D.ietf-mmusic-sdp-bundle-negotiation]

Table 30: 5.3.2 SDP Answer with SVC
Answer SDP Contents	RFC#/Notes
v=0	[RFC4566]
o=- 20519 0 IN IP4 0.0.0.0	[RFC4566]
s=-	[RFC4566]
t=0 0	[RFC4566]
a=group:BUNDLE m0 m1	[I-D.ietf-mmusic-sdp-bundle-negotiation]
a=group:LS m0 m1	[RFC5888]
a=ice-options:trickle	[I-D.ietf-mmusic-trickle-ice]
a=ice-options:ice2	[RFC8445]
**** Audio m=line *******	*****************************
m=audio 49203 UDP/TLS/RTP/SAVPF 109	[RFC4566]
c=IN IP4 203.0.113.77	[RFC4566]
a=mid:m0	[RFC5888]
a=msid:ma ta	Identifies MediaStream ID (ma) and MediaStreamTrack ID (ta)
a=recvonly	[RFC3264]
a=rtpmap:109 opus/48000/2	[RFC7587]
a=maxptime:120	[RFC4566]
a=ice-ufrag:074c6550	[I-D.ietf-mmusic-ice-sip-sdp]
a=ice-pwd:a28a397a4c3f31747d1ee3474af08a068	[I-D.ietf-mmusic-ice-sip-sdp]
a=fingerprint:sha-256 6B:8B:F0:65:5F:78:E2:51:3B:AC:6F:F3:3F:46:1B:35:DC:B8:5F:64:1A:24:C2:43:F0:A1:58:D0:A1:2C:19:08	[RFC8122]
a=setup:active	[RFC5763]
a=tls-id:CJ6FF9ZZMJW7MDRJIR7XVIQM48GE1G31	[I-D.ietf-mmusic-dtls-sdp]
a=rtcp-mux	[RFC5761]
a=rtcp-rsize	[RFC5506]
a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-level	[RFC6464]
a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid	[I-D.ietf-mmusic-sdp-bundle-negotiation]
a=candidate:0 1 UDP 2113667326 198.51.100.7 51556 typ host	[I-D.ietf-mmusic-ice-sip-sdp]
a=candidate:1 1 UDP 1694302206 203.0.113.77 49203 typ srflx raddr 198.51.100.7 rport 51556	[I-D.ietf-mmusic-ice-sip-sdp]
a=end-of-candidates	[I-D.ietf-mmusic-trickle-ice]
**** Video m=line *******	*****************************
m=video 0 UDP/TLS/RTP/SAVPF 100	BUNDLE accepted.
c=IN IP4 203.0.113.77	[RFC4566]
a=bundle-only	[I-D.ietf-mmusic-sdp-bundle-negotiation]
a=mid:m1	[RFC5888] Video m=line part of BUNDLE group
a=msid:ma tb	Identifies MediaStream ID (ma) and MediaStreamTrack ID (tb)
a=recvonly	[RFC3264] - Receive only video stream
a=rtpmap:100 H264-SVC/90000	[RFC6190]
a=fmtp:100 profile-level-id=53001f;packetization-mode=0	[RFC6190]
a=rtcp-fb:* nack	[RFC4585]
a=rtcp-fb:* nack pli	[RFC4585]
a=rtcp-fb:* ccm fir	[RFC5104]
a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid	[I-D.ietf-mmusic-sdp-bundle-negotiation]

5.3.3. Successful Simulcast Video Session with Retransmission

This section shows an SDP offer/answer exchange for a simulcast scenario with 3 resolutions and has [RFC4588]-style retransmission flows.¶

The [I-D.ietf-mmusic-rid] framework is used to specify all the (3) resolution constraints mapped to a single Payload Type (98).¶

The [I-D.ietf-mmusic-sdp-simulcast] framework identifies the simulcast streams via their 'rid' identifiers.¶



        Simulcast Streams with Retransmission

Alice                                                    Bob
|                                                         |
|                                                         |
|Alice offers single audio and simulcasted video streams  |
|                                                         |
|                                                         |
|    offer(Audio:Opus Video:VP8 with 3 resolutions)       |
|    and RTX stream                                       |
|-------------------------------------------------------->|
|                                                         |
|                                                         |
|          answer (Bob accepts Alice's offer)             |
|<--------------------------------------------------------|
|                                                         |
|                                                         |
|One-way 1 Opus, 3 VP8 and RTX video streams, all muxed   |
|.........................................................|
|                                                         |
|                                                         |

Table 31: 5.3.3 SDP Offer w/Simulcast, RTX
Offer SDP Contents	RFC#/Notes
v=0	[RFC4566]
o=- 20519 0 IN IP4 0.0.0.0	[RFC4566]
s=-	[RFC4566]
t=0 0	[RFC4566]
a=group:BUNDLE m0 m1	[I-D.ietf-mmusic-sdp-bundle-negotiation] Alice supports grouping of m=lines under BUNDLE semantics
a=group:LS m0 m1	[RFC5888]
a=ice-options:trickle	[I-D.ietf-mmusic-trickle-ice]
a=ice-options:ice2	[RFC8445]
**** Audio m=line *******	*****************************
m=audio 54609 UDP/TLS/RTP/SAVPF 109	[RFC4566]
c=IN IP4 203.0.113.141	[RFC4566]
a=mid:m0	[RFC5888] Audio m=line part of BUNDLE group with a unique port number
a=msid:ma ta	Identifies MediaStream ID (ma) and MediaStreamTrack ID (ta)
a=sendonly	[RFC3264]
a=rtpmap:109 opus/48000/2	[RFC7587]
a=maxptime:120	[RFC4566]
a=ice-ufrag:074c6550	[I-D.ietf-mmusic-ice-sip-sdp]
a=ice-pwd:a28a397a4c3f31747d1ee3474af08a068	[I-D.ietf-mmusic-ice-sip-sdp]
a=fingerprint:sha-256 19:E2:1C:3B:4B:9F:81:E6:B8:5C:F4:A5:A8:D8:73:04:BB:05:2F:70:9F:04:A9:0E:05:E9:26:33:E8:70:88:A2	[RFC8122]
a=setup:actpass	[RFC5763]
a=tls-id:89J2LRATQ3ULA24G9AHWVR31VJWSLB68	[I-D.ietf-mmusic-dtls-sdp]
a=rtcp-mux	[RFC5761]
a=rtcp-rsize	[RFC5506]
a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-level	[RFC6464]
a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid	[I-D.ietf-mmusic-sdp-bundle-negotiation]
a=candidate:0 1 UDP 2113667327 192.0.2.4 61665 typ host	[I-D.ietf-mmusic-ice-sip-sdp]
a=candidate:1 1 UDP 694302207 203.0.113.141 54609 typ srflx raddr 192.0.2.4 rport 61665	[I-D.ietf-mmusic-ice-sip-sdp]
a=end-of-candidates	[I-D.ietf-mmusic-trickle-ice]
**** Video m=line *******	*****************************
m=video 0 UDP/TLS/RTP/SAVPF 98 103	bundle-only video line with port number set to zero
c=IN IP4 203.0.113.141	[RFC4566]
a=bundle-only	[I-D.ietf-mmusic-sdp-bundle-negotiation]
a=mid:m1	[RFC5888]
a=msid:ma tb	Identifies MediaStream ID (ma) and MediaStreamTrack ID (tb)
a=sendonly	[RFC3264]
a=rtpmap:98 VP8/90000	[RFC7741]
a=fmtp:98 max-fr=30	[RFC4566]
a=rtpmap:103 rtx/90000	[RFC4588]
a=fmtp:103 apt=98;rtx-time=200	[RFC4588]
a=rtcp-fb:* nack	[RFC4585]
a=rtcp-fb:* nack pli	[RFC4585]
a=rtcp-fb:* ccm fir	[RFC5104]
a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid	[I-D.ietf-mmusic-sdp-bundle-negotiation]
a=extmap:3 urn:ietf:params:rtp-hdrext:sdes:rtp-stream-id	[I-D.ietf-avtext-rid]
a=extmap:4 urn:ietf:params:rtp-hdrext:sdes:repaired-rtp-stream-id	[I-D.ietf-avtext-rid]
a=rid:1 send pt=98;max-fs=921600;max-fr=30	[I-D.ietf-mmusic-rid]
a=rid:2 send pt=98;max-fs=614400;max-fr=15	[I-D.ietf-mmusic-rid]
a=rid:3 send pt=98;max-fs=230400;max-fr=30	[I-D.ietf-mmusic-rid]
a=simulcast:send 1;2;3	[I-D.ietf-mmusic-sdp-simulcast] Alice can send all the simulcast streams

Table 32: 5.3.3 SDP Answer w/Simulcast, RTX
Answer SDP Contents	RFC#/Notes
v=0	[RFC4566]
o=- 20519 0 IN IP4 0.0.0.0	[RFC4566]
s=-	[RFC4566]
t=0 0	[RFC4566]
a=group:BUNDLE m0 m1	[I-D.ietf-mmusic-sdp-bundle-negotiation] Bob supports grouping of m=lines under BUNDLE semantics
a=group:LS m0 m1	[RFC5888]
a=ice-options:trickle	[I-D.ietf-mmusic-trickle-ice]
a=ice-options:ice2	[RFC8445]
**** Audio m=line *******	*****************************
m=audio 49203 UDP/TLS/RTP/SAVPF 109	[RFC4566]
c=IN IP4 203.0.113.77	[RFC4566]
a=mid:m0	[RFC5888]
a=msid:ma ta	Identifies MediaStream ID (ma) and MediaStreamTrack ID (ta)
a=recvonly	[RFC3264]
a=rtpmap:109 opus/48000/2	[RFC7587]
a=maxptime:120	[RFC4566]
a=ice-ufrag:074c6550	[I-D.ietf-mmusic-ice-sip-sdp]
a=ice-pwd:a28a397a4c3f31747d1ee3474af08a068	[I-D.ietf-mmusic-ice-sip-sdp]
a=fingerprint:sha-256 6B:8B:F0:65:5F:78:E2:51:3B:AC:6F:F3:3F:46:1B:35:DC:B8:5F:64:1A:24:C2:43:F0:A1:58:D0:A1:2C:19:08	[RFC8122]
a=setup:active	[RFC5763]
a=tls-id:CJ6FF9ZZMJW7MDRJIR7XVIQM48GE1G31	[I-D.ietf-mmusic-dtls-sdp]
a=rtcp-mux	[RFC5761]
a=rtcp-rsize	[RFC5506]
a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-level	[RFC6464]
a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid	[I-D.ietf-mmusic-sdp-bundle-negotiation]
a=candidate:0 1 UDP 2113667326 198.51.100.7 51556 typ host	[I-D.ietf-mmusic-ice-sip-sdp]
a=candidate:1 1 UDP 1694302206 203.0.113.77 49203 typ srflx raddr 198.51.100.7 rport 51556	[I-D.ietf-mmusic-ice-sip-sdp]
a=end-of-candidates	[I-D.ietf-mmusic-trickle-ice]
**** Video m=line *******	*****************************
m=video 0 UDP/TLS/RTP/SAVPF 98 103	BUNDLE accepted
c=IN IP4 203.0.113.77	[RFC4566]
a=bundle-only	[I-D.ietf-mmusic-sdp-bundle-negotiation]
a=mid:m1	[RFC5888] Video m=line part of BUNDLE group
a=msid:ma tb	Identifies MediaStream ID (ma) and MediaStreamTrack ID (tb)
a=recvonly	[RFC3264]
a=rtpmap:98 VP8/90000	[RFC7741]
a=fmtp:98 max-fr=30	[RFC4566]
a=rtpmap:103 rtx/90000	[RFC4588]
a=fmtp:103 apt=98;rtx-time=200	[RFC4588]
a=rtcp-fb:* nack	[RFC4585]
a=rtcp-fb:* nack pli	[RFC4585]
a=rtcp-fb:* ccm fir	[RFC5104]
a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid	[I-D.ietf-mmusic-sdp-bundle-negotiation]
a=extmap:3 urn:ietf:params:rtp-hdrext:sdes:rtp-stream-id	[I-D.ietf-avtext-rid]
a=extmap:4 urn:ietf:params:rtp-hdrext:sdes:repaired-rtp-stream-id	[I-D.ietf-avtext-rid]
a=rid:1 recv pt=98;max-fs=921600;max-fr=30	[I-D.ietf-mmusic-rid]
a=rid:2 recv pt=98;max-fs=614400;max-fr=15	[I-D.ietf-mmusic-rid]
a=rid:3 recv pt=98;max-fs=230400;max-fr=30	[I-D.ietf-mmusic-rid]
a=simulcast:recv 1;2;3	[I-D.ietf-mmusic-sdp-simulcast] Bob accepts the offered simulcast streams

5.3.4. Successful One-way Simulcast Session with 2 resolutions and RTX - One resolution rejected

This section shows an SDP offer/answer exchange for a simulcast scenario with two resolutions.¶

It also showcases where Bob rejects one of the Simulcast Video streams, which results in the rejection of the associated repair stream implicitly.¶



     Simulcast Streams with Retransmission Rejected

Alice                                                    Bob
|                                                         |
|                                                         |
|Alice offers single audio and simulcasted video streams  |
| with bundle-only for video                              |
|                                                         |
|                                                         |
|offer(Audio:Opus Video:VP8 with 2 resolutions,RTX Stream)|
|-------------------------------------------------------->|
|                                                         |
|                                                         |Bob accepts 1
|                                                         |simulcast,rtx
|                                                         |rejects the
|                                                         |other
|   answer(Audio:Opus Video:VP8 with 1 res & RTX Stream)  |
|<--------------------------------------------------------|
|                                                         |
|                                                         |
|    One-way audio and video session and its associated   |
|    RTX stream, all multiplexed                          |
|.........................................................|
|                                                         |
|                                                         |

Table 33: 5.3.4 SDP Offer w/Simulcast, RTX
Offer SDP Contents	RFC#/Notes
v=0	[RFC4566]
o=- 20519 0 IN IP4 0.0.0.0	[RFC4566]
s=-	[RFC4566]
t=0 0	[RFC4566]
a=group:BUNDLE m0 m1	[I-D.ietf-mmusic-sdp-bundle-negotiation] Alice supports grouping of m=lines under BUNDLE semantics
a=group:LS m0 m1	[RFC5888]
a=ice-options:trickle	[I-D.ietf-mmusic-trickle-ice]
a=ice-options:ice2	[RFC8445]
**** Audio m=line *******	*****************************
m=audio 54609 UDP/TLS/RTP/SAVPF 109	[RFC4566]
c=IN IP4 203.0.113.141	[RFC4566]
a=mid:m0	[RFC5888]
a=msid:ma ta	Identifies MediaStream ID (ma) and MediaStreamTrack ID (ta)
a=sendonly	[RFC3264]
a=rtpmap:109 opus/48000/2	[RFC7587]
a=maxptime:120	[RFC4566]
a=ice-ufrag:074c6550	[I-D.ietf-mmusic-ice-sip-sdp]
a=ice-pwd:a28a397a4c3f31747d1ee3474af08a068	[I-D.ietf-mmusic-ice-sip-sdp]
a=fingerprint:sha-256 19:E2:1C:3B:4B:9F:81:E6:B8:5C:F4:A5:A8:D8:73:04:BB:05:2F:70:9F:04:A9:0E:05:E9:26:33:E8:70:88:A2	[RFC8122]
a=setup:actpass	[RFC5763]
a=tls-id:89J2LRATQ3ULA24G9AHWVR31VJWSLB68	[I-D.ietf-mmusic-dtls-sdp]
a=rtcp-mux	[RFC5761]
a=rtcp-rsize	[RFC5506]
a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-level	[RFC6464]
a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid	[I-D.ietf-mmusic-sdp-bundle-negotiation]
a=candidate:0 1 UDP 2113667327 192.0.2.4 61665 typ host	[I-D.ietf-mmusic-ice-sip-sdp]
a=candidate:1 1 UDP 694302207 203.0.113.141 54609 typ srflx raddr 192.0.2.4 rport 61665	[I-D.ietf-mmusic-ice-sip-sdp]
a=end-of-candidates	[I-D.ietf-mmusic-trickle-ice]
**** Video m=line *******	*****************************
m=video 0 UDP/TLS/RTP/SAVPF 98 100 101 103	bundle-only video line with port number set to zero
c=IN IP4 203.0.113.141	[RFC4566]
a=bundle-only	[I-D.ietf-mmusic-sdp-bundle-negotiation]
a=mid:m1	[RFC5888]
a=msid:ma tb	Identifies MediaStream ID (ma) and MediaStreamTrack ID (tb
a=sendonly	[RFC3264]
a=rtpmap:98 VP8/90000	[RFC7741]
a=rtpmap:100 VP8/90000	[RFC7741]
a=rtpmap:101 rtx/90000	[RFC4588]
a=rtpmap:103 rtx/90000	[RFC4588]
a=fmtp:98 max-fr=30;max-fs=8040	[RFC4566]
a=fmtp:100 max-fr=15;max-fs=1200	[RFC4566]
a=fmtp:101 apt=98;rtx-time=200	[RFC4588]
a=fmtp:103 apt=100;rtx-time=200	[RFC4588]
a=rtcp-fb:* nack	[RFC4585]
a=rtcp-fb:* nack pli	[RFC4585]
a=rtcp-fb:* ccm fir	[RFC5104]
a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid	[I-D.ietf-mmusic-sdp-bundle-negotiation]
a=extmap:3 urn:ietf:params:rtp-hdrext:sdes:rtp-stream-id	[I-D.ietf-avtext-rid]
a=extmap:4 urn:ietf:params:rtp-hdrext:sdes:repaired-rtp-stream-id	[I-D.ietf-avtext-rid]
a=rid:1 send pt=98	[I-D.ietf-mmusic-rid] 1:1 mapping between the PT and the 'rid' identifier
a=rid:2 send pt=100	[I-D.ietf-mmusic-rid] 1:1 mapping between the PT and the 'rid' identifier
a=simulcast:send 1;2	[I-D.ietf-mmusic-sdp-simulcast]

Table 34: 5.3.4 SDP Answer (one Simulcast Rejected)
Answer SDP Contents	RFC#/Notes
v=0	[RFC4566]
o=- 20519 0 IN IP4 0.0.0.0	[RFC4566]
s=-	[RFC4566]
t=0 0	[RFC4566]
a=group:BUNDLE m0 m1	[I-D.ietf-mmusic-sdp-bundle-negotiation] Bob supports grouping of m=lines under BUNDLE semantics
a=group:LS m0 m1	[RFC5888]
a=ice-options:trickle	[I-D.ietf-mmusic-trickle-ice]
a=ice-options:ice2	[RFC8445]
**** Audio m=line *******	*****************************
m=audio 49203 UDP/TLS/RTP/SAVPF 109	[RFC4566]
c=IN IP4 203.0.113.77	[RFC4566]
a=mid:m0	[RFC5888]
a=msid:ma ta	Identifies MediaStream ID (ma) and MediaStreamTrack ID (ta)
a=recvonly	[RFC3264]
a=rtpmap:109 opus/48000/2	[RFC7587]
a=maxptime:120	[RFC4566]
a=ice-ufrag:074c6550	[I-D.ietf-mmusic-ice-sip-sdp]
a=ice-pwd:a28a397a4c3f31747d1ee3474af08a068	[I-D.ietf-mmusic-ice-sip-sdp]
a=fingerprint:sha-256 6B:8B:F0:65:5F:78:E2:51:3B:AC:6F:F3:3F:46:1B:35:DC:B8:5F:64:1A:24:C2:43:F0:A1:58:D0:A1:2C:19:08	[RFC8122]
a=setup:active	[RFC5763]
a=tls-id:CJ6FF9ZZMJW7MDRJIR7XVIQM48GE1G31	[I-D.ietf-mmusic-dtls-sdp]
a=rtcp-mux	[RFC5761]
a=rtcp-rsize	[RFC5506]
a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-level	[RFC6464]
a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid	[I-D.ietf-mmusic-sdp-bundle-negotiation]
a=candidate:0 1 UDP 2113667326 198.51.100.7 51556 typ host	[I-D.ietf-mmusic-ice-sip-sdp]
a=candidate:1 1 UDP 1694302206 203.0.113.77 49203 typ srflx raddr 198.51.100.7 rport 51556	[I-D.ietf-mmusic-ice-sip-sdp]
a=end-of-candidates	[I-D.ietf-mmusic-trickle-ice]
**** Video m=line *******	*****************************
m=video 0 UDP/TLS/RTP/SAVPF 98 101	BUNDLE accepted
c=IN IP4 203.0.113.77	[RFC4566]
a=bundle-only	[I-D.ietf-mmusic-sdp-bundle-negotiation]
a=mid:m1	[RFC5888]
a=msid:ma tb	Identifies MediaStream ID (ma) and MediaStreamTrack ID (tb)
a=recvonly	[RFC3264]
a=rtpmap:98 VP8/90000	[RFC7741]
a=rtpmap:101 rtx/90000	[RFC4588]
a=fmtp:101 apt=98;rtx-time=200	[RFC4588]
a=rtcp-fb:* nack	[RFC4585]
a=rtcp-fb:* nack pli	[RFC4585]
a=rtcp-fb:* ccm fir	[RFC5104]
a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid	[I-D.ietf-mmusic-sdp-bundle-negotiation]
a=extmap:3 urn:ietf:params:rtp-hdrext:sdes:rtp-stream-id	[I-D.ietf-avtext-rid]
a=extmap:4 urn:ietf:params:rtp-hdrext:sdes:repaired-rtp-stream-id	[I-D.ietf-avtext-rid]
a=rid:1 recv pt=98	[I-D.ietf-mmusic-rid]
a=simulcast:recv 1	[I-D.ietf-mmusic-sdp-simulcast] Bob rejects the second simulcast stream and the associated rtx stream.

5.3.5. Simulcast Video Session with Forward Error Correction

This section shows an SDP offer/answer exchange for a simulcast video stream at two resolutions with [RFC8627] based forward error correction mechanisms.¶

On completion of the offer/answer exchange mechanism, we end up with one audio stream, 2 simulcast video streams, and associated FEC stream(s), all of which are sent over a single 5-tuple.¶


      Simulcast Streams with Forward Error Correction

Alice                                                            Bob
|                                                               |
|                                                               |
|                                                               |
|Alice offers single audio and simulcasted video streams        |
|with bundle-only                                               |
|                                                               |
|                                                               |
|offer(Audio:Opus Video:VP8 with 2 resolutions with FEC Streams)|
|-------------------------------------------------------------->|
|                                                               |
|                                                               |Bob
|                                                               |accepts
|                                                               |Alice's
|                                                               |offer
|answer(Audio:Opus Video:VP8 with 2 resolutions w/FEC Streams)  |
|<--------------------------------------------------------------|
|                                                               |
|One-way Audio,Video session with 2 video streams and           |
| associated FEC stream(s)                                      |
|...............................................................|
|                                                               |
|                                                               |
|                                                               |

Table 35: 5.3.5 SDP Offer
Offer SDP Contents	RFC#/Notes
v=0	[RFC4566]
o=- 20519 0 IN IP4 0.0.0.0	[RFC4566]
s=-	[RFC4566]
t=0 0	[RFC4566]
a=group:BUNDLE m0 m1	[I-D.ietf-mmusic-sdp-bundle-negotiation] Alice supports grouping of m=lines under BUNDLE semantics
a=group:LS m0 m1	[RFC5888]
a=ice-options:trickle	[I-D.ietf-mmusic-trickle-ice]
a=ice-options:ice2	[RFC8445]
**** Audio m=line *******	*****************************
m=audio 54609 UDP/TLS/RTP/SAVPF 109	[RFC4566]
c=IN IP4 203.0.113.141	[RFC4566]
a=mid:m0	[RFC5888]
a=msid:ma ta	Identifies MediaStream ID (ma) and MediaStreamTrack ID (ta)
a=sendonly	[RFC3264]
a=rtpmap:109 opus/48000/2	[RFC7587]
a=maxptime:120	[RFC4566]
a=ice-ufrag:074c6550	[I-D.ietf-mmusic-ice-sip-sdp]
a=ice-pwd:a28a397a4c3f31747d1ee3474af08a068	[I-D.ietf-mmusic-ice-sip-sdp]
a=fingerprint:sha-256 19:E2:1C:3B:4B:9F:81:E6:B8:5C:F4:A5:A8:D8:73:04:BB:05:2F:70:9F:04:A9:0E:05:E9:26:33:E8:70:88:A2	[RFC8122]
a=setup:actpass	[RFC5763]
a=rtcp-mux	[RFC5761]
a=tls-id:89J2LRATQ3ULA24G9AHWVR31VJWSLB68	[I-D.ietf-mmusic-dtls-sdp]
a=rtcp-rsize	[RFC5506]
a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-level	[RFC6464]
a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid	[I-D.ietf-mmusic-sdp-bundle-negotiation]
a=candidate:0 1 UDP 2113667327 192.0.2.4 61665 typ host	[I-D.ietf-mmusic-ice-sip-sdp]
a=candidate:1 1 UDP 694302207 203.0.113.141 54609 typ srflx raddr 192.0.2.4 rport 61665	[I-D.ietf-mmusic-ice-sip-sdp]
a=end-of-candidates	[I-D.ietf-mmusic-trickle-ice]
**** Video m=line *******	*****************************
m=video 0 UDP/TLS/RTP/SAVPF 98 100 101	bundle-only video line with port number set to zero
c=IN IP4 203.0.113.141	[RFC4566]
a=bundle-only	[I-D.ietf-mmusic-sdp-bundle-negotiation]
a=mid:m1	[RFC5888] Video m=line part of BUNDLE group
a=msid:ma tb	Identifies MediaStream ID (ma) and MediaStreamTrack ID (tb)
a=sendonly	[RFC3264]
a=rtpmap:98 VP8/90000	[RFC7741]
a=rtpmap:100 VP8/90000	[RFC7741]
a=rtpmap:101 flexfec/90000	[RFC8627]
a=fmtp:98 max-fr=30;max-fs=8040	[RFC4566]
a=fmtp:100 max-fr=15;max-fs=1200	[RFC4566]
a=fmtp:101 repair-window=200000	[RFC8627]
a=rtcp-fb:* nack pli	[RFC4585]
a=rtcp-fb:* ccm fir	[RFC5104]
a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid	[I-D.ietf-mmusic-sdp-bundle-negotiation]
a=extmap:3 urn:ietf:params:rtp-hdrext:sdes:rtp-stream-id	[I-D.ietf-avtext-rid]
a=extmap:4 urn:ietf:params:rtp-hdrext:sdes:repaired-rtp-stream-id	[I-D.ietf-avtext-rid]
a=rid:1 send pt=98	[I-D.ietf-mmusic-rid] 1:1 mapping between the PT and the 'rid' identifier
a=rid:2 send pt=100	[I-D.ietf-mmusic-rid] 1:1 mapping between the PT and the 'rid' identifier
a=simulcast:send 1;2	[I-D.ietf-mmusic-sdp-simulcast]

Table 36: 5.3.5 SDP Answer
Answer SDP Contents	RFC#/Notes
v=0	[RFC4566]
o=- 20519 0 IN IP4 0.0.0.0	[RFC4566]
s=-	[RFC4566]
t=0 0	[RFC4566]
a=group:BUNDLE m0 m1	[I-D.ietf-mmusic-sdp-bundle-negotiation]
a=group:LS m0 m1	[RFC5888]
a=ice-options:trickle	[I-D.ietf-mmusic-trickle-ice]
a=ice-options:ice2	[RFC8445]
**** Audio m=line *******	*****************************
m=audio 49203 UDP/TLS/RTP/SAVPF 109	[RFC4566]
c=IN IP4 203.0.113.77	[RFC4566]
a=mid:m0	[RFC5888] Audio m=line part of BUNDLE group with a unique port number
a=msid:ma ta	Identifies MediaStream ID (ma) and MediaStreamTrack ID (ta)
a=recvonly	[RFC3264]
a=rtpmap:109 opus/48000/2	[RFC7587]
a=maxptime:120	[RFC4566]
a=ice-ufrag:074c6550	[I-D.ietf-mmusic-ice-sip-sdp]
a=ice-pwd:a28a397a4c3f31747d1ee3474af08a068	[I-D.ietf-mmusic-ice-sip-sdp]
a=fingerprint:sha-256 6B:8B:F0:65:5F:78:E2:51:3B:AC:6F:F3:3F:46:1B:35:DC:B8:5F:64:1A:24:C2:43:F0:A1:58:D0:A1:2C:19:08	[RFC8122]
a=setup:active	[RFC5763]
a=tls-id:CJ6FF9ZZMJW7MDRJIR7XVIQM48GE1G31	[I-D.ietf-mmusic-dtls-sdp]
a=rtcp-mux	[RFC5761]
a=rtcp-rsize	[RFC5506]
a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-level	[RFC6464]
a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid	[I-D.ietf-mmusic-sdp-bundle-negotiation]
a=candidate:0 1 UDP 2113667326 198.51.100.7 51556 typ host	[I-D.ietf-mmusic-ice-sip-sdp]
a=candidate:1 1 UDP 1694302206 203.0.113.77 49203 typ srflx raddr 198.51.100.7 rport 51556	[I-D.ietf-mmusic-ice-sip-sdp]
a=end-of-candidates	[I-D.ietf-mmusic-trickle-ice]
**** Video m=line *******	*****************************
m=video 0 UDP/TLS/RTP/SAVPF 98 100 101	BUNDLE accepted.
c=IN IP4 203.0.113.77	[RFC4566]
a=bundle-only	[I-D.ietf-mmusic-sdp-bundle-negotiation]
a=mid:m1	[RFC5888] Video m=line part of BUNDLE group
a=msid:ma tb	Identifies MediaStream ID (ma) and MediaStreamTrack ID (tb)
a=recvonly	[RFC3264]
a=rtpmap:98 VP8/90000	[RFC7741]
a=rtpmap:100 VP8/90000	[RFC7741]
a=rtpmap:101 flexfec/90000	[RFC8627]
a=fmtp:98 max-fr=30;max-fs=8040	[RFC4566]
a=fmtp:100 max-fr=15;max-fs=1200	[RFC4566]
a=fmtp:101 repair-window=200000	[RFC8627]
a=rtcp-fb:* nack pli	[RFC4585]
a=rtcp-fb:* ccm fir	[RFC5104]
a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid	[I-D.ietf-mmusic-sdp-bundle-negotiation]
a=extmap:3 urn:ietf:params:rtp-hdrext:sdes:rtp-stream-id	[I-D.ietf-avtext-rid]
a=extmap:4 urn:ietf:params:rtp-hdrext:sdes:repaired-rtp-stream-id	[I-D.ietf-avtext-rid]
a=rid:1 recv pt=98	[I-D.ietf-mmusic-rid]
a=rid:2 recv pt=100	[I-D.ietf-mmusic-rid]
a=simulcast:recv 1;2	[I-D.ietf-mmusic-sdp-simulcast]

5.4. Others

The examples in this section provide SDP offer/answer exchanges for a variety of scenarios related to RTP Header extensions for conference usages, Legacy Interop scenarios, and more.¶

5.4.1. Audio Session - Voice Activity Detection

This example shows Alice indicating the support of the RTP header extension to include the audio level of the audio sample carried in the RTP packet.¶

           Two-way Audio with VAD

 Alice                                    Bob
 |                                         |
 |                                         |
 |Alice indicates support for including    |
 |audio level in RTP header                |
 |                                         |
 |     offer(Audio:Opus,PCMU,PCMA)         |
 |---------------------------------------->|
 |                                         |
 |                                         |
 |     answer(Audio:Opus,PCMU,PCMA)        |
 |<----------------------------------------|
 |                                         |
 |                                         |Bob accepts and
 |                                         |indicates his
 |                                         |support as well
 |                                         |
 |     Two-way Opus Audio                  |
 |.........................................|
 |                                         |
 |Per packet audio-level is included in the|
 |RTP header                               |
 |                                         |

Table 37: 5.4.1 SDP Offer
Offer SDP Contents	RFC#/Notes
v=0	[RFC4566]
o=- 20518 0 IN IP4 0.0.0.0	[RFC4566]
s=-	[RFC4566]
t=0 0	[RFC4566]
a=group:BUNDLE audio	[I-D.ietf-mmusic-sdp-bundle-negotiation]
a=ice-options:trickle	[I-D.ietf-mmusic-trickle-ice]
a=ice-options:ice2	[RFC8445]
**** Audio m=line *******	*****************************
m=audio 54609 UDP/TLS/RTP/SAVPF 109 0 8	[RFC4566]
c=IN IP4 203.0.113.141	[RFC4566]
a=mid:audio	[RFC5888]
a=msid:ma ta	Identifies MediaStream ID (ma) and MediaStreamTrack ID (ta)
a=sendrecv	[RFC3264]
a=rtpmap:109 opus/48000/2	[RFC7587]
a=rtpmap:0 PCMU/8000	[RFC3551]
a=rtpmap:8 PCMA/8000	[RFC3551]
a=maxptime:120	[RFC4566]
a=ice-ufrag:074c6550	[I-D.ietf-mmusic-ice-sip-sdp]
a=ice-pwd:a28a397a4c3f31747d1ee3474af08a068	[I-D.ietf-mmusic-ice-sip-sdp]
a=fingerprint:sha-256 19:E2:1C:3B:4B:9F:81:E6:B8:5C:F4:A5:A8:D8:73:04:BB:05:2F:70:9F:04:A9:0E:05:E9:26:33:E8:70:88:A2	[RFC8122]
a=setup:actpass	[RFC5763]
a=tls-id:89J2LRATQ3ULA24G9AHWVR31VJWSLB68	[I-D.ietf-mmusic-dtls-sdp]
a=rtcp-mux	[RFC5761]
a=rtcp-rsize	[RFC5506]
a=rtcp-fb:* nack	[RFC4585]
a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-level	[RFC6464]
a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid	[I-D.ietf-mmusic-sdp-bundle-negotiation]
a=candidate:0 1 UDP 2113667327 192.0.2.4 61665 typ host	[I-D.ietf-mmusic-ice-sip-sdp]
a=candidate:1 1 UDP 694302207 203.0.113.141 54609 typ srflx raddr 192.0.2.4 rport 61665	[I-D.ietf-mmusic-ice-sip-sdp]
a=end-of-candidates	[I-D.ietf-mmusic-trickle-ice]

Table 38: 5.4.1 SDP Answer
Answer SDP Contents	RFC#/Notes
v=0	[RFC4566]
o=- 16833 0 IN IP4 0.0.0.0	[RFC4566]
s=-	[RFC4566]
t=0 0	[RFC4566]
a=group:BUNDLE audio	[I-D.ietf-mmusic-sdp-bundle-negotiation]
a=ice-options:trickle	[I-D.ietf-mmusic-trickle-ice]
a=ice-options:ice2	[RFC8445]
**** Audio m=line *******	*****************************
m=audio 49203 UDP/TLS/RTP/SAVPF 109 0 8	[RFC4566]
c=IN IP4 203.0.113.77	[RFC4566]
a=mid:audio	[RFC5888]
a=msid:ma ta	Identifies MediaStream ID (ma) and MediaStreamTrack ID (ta)
a=sendrecv	[RFC3264] - Bob can send and recv audio
a=rtpmap:109 opus/48000/2	[RFC7587] - Bob accepts only Opus Codec
a=rtpmap:0 PCMU/8000	[RFC3551] PCMU Audio Codec
a=rtpmap:8 PCMA/8000	[RFC3551] PCMA Audio Codec
a=maxptime:120	[RFC4566]
a=ice-ufrag:c300d85b	[I-D.ietf-mmusic-ice-sip-sdp]
a=ice-pwd:de4e99bd291c325921d5d47efbabd9a2	[I-D.ietf-mmusic-ice-sip-sdp]
a=fingerprint:sha-256 6B:8B:F0:65:5F:78:E2:51:3B:AC:6F:F3:3F:46:1B:35:DC:B8:5F:64:1A:24:C2:43:F0:A1:58:D0:A1:2C:19:08	[RFC8122]
a=setup:active	[RFC5763]
a=tls-id:CJ6FF9ZZMJW7MDRJIR7XVIQM48GE1G31	[I-D.ietf-mmusic-dtls-sdp]
a=rtcp-mux	[RFC5761] - Bob can perform RTP/RTCP Muxing on port 49203
a=rtcp-rsize	[RFC5506]
a=rtcp-fb:* nack	[RFC4585]
a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-level	[RFC6464]
a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid	[I-D.ietf-mmusic-sdp-bundle-negotiation]
a=candidate:0 1 UDP 2113667327 198.51.100.7 51556 typ host	[I-D.ietf-mmusic-ice-sip-sdp]
a=candidate:1 1 UDP 1694302207 203.0.113.77 49203 typ srflx raddr 198.51.100.7 rport 51556	[I-D.ietf-mmusic-ice-sip-sdp]
a=end-of-candidates	[I-D.ietf-mmusic-trickle-ice]

5.4.2. Audio Conference - Voice Activity Detection

This example of SDP highlights the RTP header RTP header extension that allows RTP-level mixers in audio conferences to deliver information about the audio level of individual participants.¶



     Audio Conference with VAD Support

Alice                                    Mixer
|                                         |
|Alice indicates her interest in audio    |
|levels for the contributing sources      |
|                                         |
|offer(Audio:Opus,PCMU,PCMA)              |
|---------------------------------------->|
|                                         |
|                                         |
|answer(Audio:Opus,PCMU,PCMA)             |
|<----------------------------------------|
|                                         |
|                                         |Mixer indicates
|                                         |it can provide
|                                         |audio-levels
|Two-way Opus Audio                       |
|.........................................|
|                                         |
|audio-levels per CSRCS are included in   |
|the RTP header                           |
|                                         |

Table 39: 5.4.2 SDP Offer
Offer SDP Contents	RFC#/Notes
v=0	[RFC4566]
o=- 20518 0 IN IP4 0.0.0.0	[RFC4566] - Session Origin Information
s=-	[RFC4566]
t=0 0	[RFC4566]
a=group:BUNDLE audio	[I-D.ietf-mmusic-sdp-bundle-negotiation]
a=ice-options:trickle	[I-D.ietf-mmusic-trickle-ice]
a=ice-options:ice2	[RFC8445]
**** Audio m=line *******	*****************************
m=audio 54609 UDP/TLS/RTP/SAVPF 109 0 8	[RFC4566]
c=IN IP4 203.0.113.141	[RFC4566]
a=mid:audio	[RFC5888]
a=msid:ma ta	Identifies MediaStream ID (ma) and MediaStreamTrack ID (ta)
a=sendrecv	[RFC3264] - Alice can send and recv audio
a=rtpmap:109 opus/48000/2	[RFC7587]
a=rtpmap:0 PCMU/8000	[RFC3551] PCMU Audio Codec
a=rtpmap:8 PCMA/8000	[RFC3551] PCMA Audio Codec
a=maxptime:120	[RFC4566]
a=ice-ufrag:074c6550	[I-D.ietf-mmusic-ice-sip-sdp]
a=ice-pwd:a28a397a4c3f31747d1ee3474af08a068	[I-D.ietf-mmusic-ice-sip-sdp]
a=fingerprint:sha-256 19:E2:1C:3B:4B:9F:81:E6:B8:5C:F4:A5:A8:D8:73:04:BB:05:2F:70:9F:04:A9:0E:05:E9:26:33:E8:70:88:A2	[RFC8122]
a=setup:actpass	[RFC5763]
a=tls-id:89J2LRATQ3ULA24G9AHWVR31VJWSLB68	[I-D.ietf-mmusic-dtls-sdp]
a=rtcp-mux	[RFC5761]
a=rtcp-rsize	[RFC5506]
a=rtcp-fb:* nack	[RFC4585]
a=extmap:1/recvonly urn:ietf:params:rtp-hdrext:csrc-audio-level	[RFC6465]
a=extmap:2 urn:ietf:params:rtp-hdrext:ssrc-audio-level	[RFC6464]
a=extmap:3 urn:ietf:params:rtp-hdrext:sdes:mid	[I-D.ietf-mmusic-sdp-bundle-negotiation]
a=candidate:0 1 UDP 2113667327 192.0.2.4 61665 typ host	[I-D.ietf-mmusic-ice-sip-sdp]
a=candidate:1 1 UDP 694302207 203.0.113.141 54609 typ srflx raddr 192.0.2.4 rport 61665	[I-D.ietf-mmusic-ice-sip-sdp]
a=end-of-candidates	[I-D.ietf-mmusic-trickle-ice]

Table 40: 5.4.2 SDP Answer
Answer SDP Contents	RFC#/Notes
v=0	[RFC4566]
o=- 16833 0 IN IP4 0.0.0.0	[RFC4566] - Session Origin Information
s=-	[RFC4566]
t=0 0	[RFC4566]
a=group:BUNDLE audio	[I-D.ietf-mmusic-sdp-bundle-negotiation]
a=ice-options:trickle	[I-D.ietf-mmusic-trickle-ice]
a=ice-options:ice2	[RFC8445]
**** Audio m=line *******	*****************************
m=audio 49203 UDP/TLS/RTP/SAVPF 109 0 8	[RFC4566]
c=IN IP4 203.0.113.77	[RFC4566]
a=mid:audio	[RFC5888]
a=msid:ma ta	Identifies MediaStream ID (ma) and MediaStreamTrack ID (ta)
a=sendrecv	[RFC3264]
a=rtpmap:109 opus/48000/2	[RFC7587]
a=rtpmap:0 PCMU/8000	[RFC3551] PCMU Audio Codec
a=rtpmap:8 PCMA/8000	[RFC3551] PCMA Audio Codec
a=maxptime:120	[RFC4566]
a=ice-ufrag:c300d85b	[I-D.ietf-mmusic-ice-sip-sdp]
a=ice-pwd:de4e99bd291c325921d5d47efbabd9a2	[I-D.ietf-mmusic-ice-sip-sdp]
a=fingerprint:sha-256 6B:8B:F0:65:5F:78:E2:51:3B:AC:6F:F3:3F:46:1B:35:DC:B8:5F:64:1A:24:C2:43:F0:A1:58:D0:A1:2C:19:08	[RFC8122]
a=setup:active	[RFC5763]
a=tls-id:CJ6FF9ZZMJW7MDRJIR7XVIQM48GE1G31	[I-D.ietf-mmusic-dtls-sdp]
a=rtcp-mux	[RFC5761]
a=rtcp-rsize	[RFC5506]
a=rtcp-fb:* nack	[RFC4585]
a=extmap:1/sendonly urn:ietf:params:rtp-hdrext:csrc-audio-level	[RFC6465]
a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid	[I-D.ietf-mmusic-sdp-bundle-negotiation]
a=candidate:0 1 UDP 2113667327 198.51.100.7 51556 typ host	[I-D.ietf-mmusic-ice-sip-sdp]
a=candidate:1 1 UDP 1694302207 203.0.113.77 49203 typ srflx raddr 198.51.100.7 rport 51556	[I-D.ietf-mmusic-ice-sip-sdp]
a=end-of-candidates	[I-D.ietf-mmusic-trickle-ice]

5.4.3. Successful Legacy Interop Fallback with bundle-only

In the scenario described below, Alice is a multi-stream capable WebRTC endpoint, while Bob is a legacy VOIP endpoint. The SDP offer/answer exchange demonstrates successful session setup with fallback to an audio-only stream negotiated via the bundle-only framework between the endpoints. Specifically:¶

The offer from Alice describes 2 cameras via 2 video m=lines with both marked as bundle-only.¶
Bob doesn't recognize the BUNDLE mechanism and since Alice has marked both the video m=lines with port 0, Bob accepts just the audio stream from Alice.¶

NOTE: Alice is unaware of whether Bob supports the BUNDLE framework. Alice includes separate RTP/RTCP ports and candidate information.¶


         Successful Two-way WebRTC <-> VOIP Interop

Alice                                                       Bob
|                                                           |
|                                                           |
|       Alice is a multistream capable WebRTC endpoint      |
|          & Bob is behind a legacy VOIP system             |
|                                                           |
|offer(Audio:Opus Video:1 VP8,1 H.264 Stream) with          |
|          bundle-only                                      |
|---------------------------------------------------------->|
|     Alice marks both the video streams as bundle-only     |
|                                                           |
|                                                           |
|                  answer(Audio:Opus)                       |
|<----------------------------------------------------------|
|                                                           |Bob
|                                                           |accepts the
|                                                           |audio
|                                                           |stream,
|                                                           |since he
|                                                           |doesn't
|                                                           |recognize
|                                                           |bundle-only
|                                                           |
|                   Two-way Opus Audio                      |
|...........................................................|
|                                                           |
|                                                           |

Table 41: 5.4.3 SDP Simulcast bundle-only
Offer SDP Contents	RFC#/Notes
v=0	[RFC4566]
o=- 20519 0 IN IP4 0.0.0.0	[RFC4566]
s=-	[RFC4566]
t=0 0	[RFC4566]
a=group:BUNDLE m0 m1 m2	[I-D.ietf-mmusic-sdp-bundle-negotiation] Alice supports grouping of m=lines under BUNDLE semantics
a=group:LS m0 m1	[RFC5888]
a=ice-options:trickle	[I-D.ietf-mmusic-trickle-ice]
a=ice-options:ice2	[RFC8445]
**** Audio m=line *******	*****************************
m=audio 54609 UDP/TLS/RTP/SAVPF 109	[RFC4566]
c=IN IP4 203.0.113.141	[RFC4566]
a=mid:m0	[RFC5888] Audio m=line part of BUNDLE group with a unique port number
a=msid:ma ta	Identifies MediaStream ID (ma) and MediaStreamTrack ID (ta)
a=sendrecv	[RFC3264]
a=rtpmap:109 opus/48000/2	[RFC7587]
a=maxptime:120	[RFC4566]
a=ice-ufrag:074c6550	[I-D.ietf-mmusic-ice-sip-sdp]
a=ice-pwd:a28a397a4c3f31747d1ee3474af08a068	[I-D.ietf-mmusic-ice-sip-sdp]
a=fingerprint:sha-256 19:E2:1C:3B:4B:9F:81:E6:B8:5C:F4:A5:A8:D8:73:04:BB:05:2F:70:9F:04:A9:0E:05:E9:26:33:E8:70:88:A2	[RFC8122]
a=setup:actpass	[RFC5763]
a=tls-id:89J2LRATQ3ULA24G9AHWVR31VJWSLB68	[I-D.ietf-mmusic-dtls-sdp]
a=rtcp-mux	[RFC5761]
a=rtcp:64678 IN IP4 203.0.113.141	[RFC3605]
a=rtcp-rsize	[RFC5506]
a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-level	[RFC6464]
a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid	[I-D.ietf-mmusic-sdp-bundle-negotiation]
a=candidate:0 1 UDP 2113667327 192.0.2.4 61665 typ host	[I-D.ietf-mmusic-ice-sip-sdp]
a=candidate:1 1 UDP 694302207 203.0.113.141 54609 typ srflx raddr 192.0.2.4 rport 61665	[I-D.ietf-mmusic-ice-sip-sdp]
a=candidate:0 1 UDP 2113667326 192.0.2.4 61667 typ host	[I-D.ietf-mmusic-ice-sip-sdp]
a=candidate:1 1 UDP 1694302206 203.0.113.141 64678 typ srflx raddr 192.0.2.4 rport 61667	[I-D.ietf-mmusic-ice-sip-sdp]
**** Video-1 m=line *******	*****************************
m=video 0 UDP/TLS/RTP/SAVPF 98	bundle-only video line with port number set to zero
c=IN IP4 203.0.113.141	[RFC4566]
a=bundle-only	[I-D.ietf-mmusic-sdp-bundle-negotiation]
a=mid:m1	[RFC5888] Video m=line part of BUNDLE group
a=msid:ma tb	Identifies MediaStream ID (ma) and MediaStreamTrack ID (tb)
a=sendrecv	[RFC3264]
a=rtpmap:98 VP8/90000	[RFC7741]
a=imageattr:98 [x=1280,y=720]	[RFC6236]
a=fmtp:98 max-fr=30	[RFC4566]
a=rtcp-fb:* nack	[RFC4585]
a=rtcp-fb:* nack pli	[RFC4585]
a=rtcp-fb:* ccm fir	[RFC5104]
a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid	[I-D.ietf-mmusic-sdp-bundle-negotiation]
**** Video-2 m=line *******	*****************************
m=video 0 UDP/TLS/RTP/SAVPF 101	bundle-only video line with port number set to zero
c=IN IP4 203.0.113.141	[RFC4566]
a=bundle-only	[I-D.ietf-mmusic-sdp-bundle-negotiation]
a=mid:m2	[RFC5888] Video m=line part of BUNDLE group
a=msid:ma tc	Identifies MediaStream ID (ma) and MediaStreamTrack ID (tc)
a=sendrecv	[RFC3264]
a=rtpmap:101 H264/90000	[RFC6184]
a=fmtp:101 profile-level-id=4d0028;packetization-mode=1	[RFC6184]Camera-2,Encoding-1 Resolution
a=rtcp-fb:* nack	[RFC4585]
a=rtcp-fb:* nack pli	[RFC4585]
a=rtcp-fb:* ccm fir	[RFC5104]
a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid	[I-D.ietf-mmusic-sdp-bundle-negotiation]

Table 42: 5.4.3 SDP Answer
Answer SDP Contents	RFC#/Notes
v=0	[RFC4566]
o=- 20519 0 IN IP4 0.0.0.0	[RFC4566]
s=-	[RFC4566]
t=0 0	[RFC4566]
**** Audio m=line *******	*****************************
m=audio 49203 UDP/TLS/RTP/SAVPF 109	[RFC4566]
c=IN IP4 203.0.113.141	[RFC4566]
a=rtcp:60065 IN IP4 203.0.113.141	[RFC3605]
a=sendrecv	[RFC3264]
a=rtpmap:109 opus/48000/2	[RFC7587]
a=maxptime:120	[RFC4566]
a=ice-ufrag:c300d85b	[I-D.ietf-mmusic-ice-sip-sdp]
a=ice-pwd:de4e99bd291c325921d5d47efbabd9a2	[I-D.ietf-mmusic-ice-sip-sdp]
a=fingerprint:sha-256 6B:8B:F0:65:5F:78:E2:51:3B:AC:6F:F3:3F:46:1B:35:DC:B8:5F:64:1A:24:C2:43:F0:A1:58:D0:A1:2C:19:08	[RFC8122]
a=setup:active	[RFC5763]
a=rtcp-rsize	[RFC5506]
a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-level	[RFC6464]
a=candidate:0 1 UDP 2113667327 198.51.100.7 51556 typ host	[I-D.ietf-mmusic-ice-sip-sdp]
a=candidate:1 1 UDP 694302207 203.0.113.77 49203 typ srflx raddr 198.51.100.7 rport 51556	[I-D.ietf-mmusic-ice-sip-sdp]
a=candidate:0 2 UDP 2113667326 198.51.100.7 51558 typ host	[I-D.ietf-mmusic-ice-sip-sdp]
a=candidate:1 2 UDP 1694302206 203.0.113.77 60065 typ srflx raddr 198.51.100.7 rport 51558	[I-D.ietf-mmusic-ice-sip-sdp]
**** Video m=line *******	*****************************
m=video 0 UDP/TLS/RTP/SAVPF 98	Bob doesn't recognize bundle-only and hence the m=line is rejected implicitly due to port 0
**** Video m=line *******	*****************************
m=video 0 UDP/TLS/RTP/SAVPF 101	Bob doesn't recognize bundle-only and hence the m=line is rejected implicitly due to port 0

5.4.4. Legacy Interop with RTP/AVP profile

In the scenario described below, Alice is a legacy endpoint that sends an [RFC3264] offer with RTP/AVP-based audio and video descriptions along with a DTLS fingerprint and RTCP feedback information.¶

On the other hand, Bob, being a WebRTC endpoint, follows the procedures in section 5.1.2 of [I-D.ietf-rtcweb-jsep] and accepts the Alice's offer for a DTLS-SRTP-based session with RTCP feedback.¶


           Successful Two-way WebRTC <-> VOIP Interop

Alice                                                       Bob
|                                                            |
|                                                            |
|Alice is a legacy VOIP endpoint & Bob is a WebRTC endpoint  |
|                                                            |
|                                                            |
|                                                            |
|              offer(Audio:Opus Video:H.264)                 |
|----------------------------------------------------------->|
|                                                            |
|                                                            |
|Alice includes :                                            |
|Legacy-compliant media description (RTP/AVP) with DTLS      |
|fingerprint and RTCP feedback support                       |
|                                                            |
|             answer(Audio:Opus, Video:H.264)                |
|<-----------------------------------------------------------|
|                                                            |Bob
|                                                            |accepts
|                                                            |"legacy
|                                                            |-compliant"
|                                                            |m=line
|                                                            |
|                                                            |
|             Two-way Opus Audio, H.264 Video                |
|............................................................|
|       Session also supports RTP/RTCP Mux, RTCP Feedback    |
|                                                            |

Table 43: 5.4.5 SDP Offer
Offer SDP Contents	RFC#/Notes
v=0	[RFC4566]
o=- 20518 0 IN IP4 0.0.0.0	[RFC4566]
s=-	[RFC4566]
t=0 0	[RFC4566]
a=ice-ufrag:074c6550	[I-D.ietf-mmusic-ice-sip-sdp]
a=ice-pwd:a28a397a4c3f31747d1ee3474af08a068	[I-D.ietf-mmusic-ice-sip-sdp]
a=rtcp-rsize	[RFC5506]
**** Audio m=line *******	*****************************
m=audio 54732 RTP/AVP 109	[RFC4566]Alice includes RTP/AVP audio stream description
c=IN IP4 203.0.113.141	[RFC4566]
a=fingerprint:sha-256 19:E2:1C:3B:4B:9F:81:E6:B8:5C:F4:A5:A8:D8:73:04:BB:05:2F:70:9F:04:A9:0E:05:E9:26:33:E8:70:88:A2	[RFC8122]
a=rtpmap:109 opus/48000
a=ptime:20
a=sendrecv	[RFC3264]
a=rtcp-mux	[RFC5761]Alice still includes RTP/RTCP Mux support
a=rtcp:64678 IN IP4 203.0.113.141	[RFC3605]
a=candidate:0 1 UDP 2113667327 192.0.2.4 54732 typ host	[I-D.ietf-mmusic-ice-sip-sdp]
a=candidate:1 1 UDP 694302207 203.0.113.141 54732 typ srflx raddr 192.0.2.4 rport 54732	[I-D.ietf-mmusic-ice-sip-sdp]
a=candidate:0 2 UDP 2113667326 192.0.2.4 64678 typ host	[I-D.ietf-mmusic-ice-sip-sdp]
a=candidate:1 2 UDP 1694302206 203.0.113.141 64678 typ srflx raddr 192.0.2.4 rport 64678	[I-D.ietf-mmusic-ice-sip-sdp]
**** Video m=line *******	*****************************
m=video 62445 RTP/AVP 120	[RFC4566]Alice includes RTP/AVP video stream description
c=IN IP4 203.0.113.141	[RFC4566]
a=fingerprint:sha-256 DC:B8:5F:64:1A:24:C2:43:F0:A1:58:D0:A1:2C:19:08:6B:8B:F0:65:5F:78:E2:51:3B:AC:6F:F3:3F:46:1B:35	[RFC8122]
a=rtpmap:120 VP8/90000	[RFC7741]
a=sendrecv	[RFC3264]
a=rtcp-mux	[RFC5761]Alice intends to perform RTP/RTCP Mux
a=rtcp:54721 IN IP4 203.0.113.141	[RFC3605]
a=candidate:0 1 UDP 2113667327 192.0.2.4 62445 typ host	[I-D.ietf-mmusic-ice-sip-sdp]
a=candidate:1 1 UDP 1694302207 203.0.113.141 62537 typ srflx raddr 192.0.2.4 rport 62445	[I-D.ietf-mmusic-ice-sip-sdp]
a=candidate:0 2 UDP 2113667326 192.0.2.4 54721 typ host	[I-D.ietf-mmusic-ice-sip-sdp]
a=candidate:1 2 UDP 1694302206 203.0.113.141 54721 typ srflx raddr 192.0.2.4 rport 54721	[I-D.ietf-mmusic-ice-sip-sdp]
a=rtcp-fb:120 nack pli	[RFC4585] Alice indicates support for Picture Loss Indication and NACK RTCP feedback
a=rtcp-fb:120 ccm fir	[RFC5104]

Table 44: 5.4.5 SDP Answer
Answer SDP Contents	RFC#/Notes
v=0	[RFC4566]
o=- 16833 0 IN IP4 0.0.0.0	[RFC4566]
s=-	[RFC4566]
t=0 0	[RFC4566]
**** Audio m=line *******	*****************************
m=audio 49203 RTP/AVP 109	[RFC4566] Bob accepts RTP/AVP-based audio stream
c=IN IP4 203.0.113.77	[RFC4566]
a=rtpmap:109 opus/48000
a=ptime:20
a=sendrecv	[RFC3264]
a=ice-ufrag:c300d85b	[I-D.ietf-mmusic-ice-sip-sdp]
a=ice-pwd:de4e99bd291c325921d5d47efbabd9a2	[I-D.ietf-mmusic-ice-sip-sdp]
a=fingerprint:sha-256 BB:05:2F:70:9F:04:A9:0E:05:E9:26:33:E8:70:88:A2:19:E2:1C:3B:4B:9F:81:E6:B8:5C:F4:A5:A8:D8:73:04	[RFC8122]
a=rtcp-mux	[RFC5761]
a=candidate:0 1 UDP 2113667327 198.51.100.7 49203 typ host	[I-D.ietf-mmusic-ice-sip-sdp]
a=candidate:1 1 UDP 1694302207 203.0.113.77 49203 typ srflx raddr 198.51.100.7 rport 49203	[I-D.ietf-mmusic-ice-sip-sdp]
**** Video m=line *******	*****************************
m=video 63130 RTP/AVP 120	[RFC4566] Bob accepts RTP/AVP-based video stram
c=IN IP4 203.0.113.77	[RFC4566]
a=rtpmap:120 VP8/90000	[RFC7741]
a=sendrecv	[RFC3264]
a=ice-ufrag:e39091na	[I-D.ietf-mmusic-ice-sip-sdp]
a=ice-pwd:dbc325921d5dd29e4e99147efbabd9a2	[I-D.ietf-mmusic-ice-sip-sdp]
a=fingerprint:sha-256 BB:0A:0E:05:E9:26:33:E8:70:88:A2:2F:70:9F:04:19:E2:1C:3B:4B:9F:81:56:2F:70:9F:04:F4:A5:A8:D8	[RFC8122]
a=rtcp-mux	[RFC5761]
a=candidate:0 1 UDP 2113667327 198.51.100.7 63130 typ host	[I-D.ietf-mmusic-ice-sip-sdp]
a=candidate:1 1 UDP 1694302207 203.0.113.77 63130 typ srflx raddr 198.51.100.7 rport 63130	[I-D.ietf-mmusic-ice-sip-sdp]
a=rtcp-fb:120 nack pli	[RFC4585]
a=rtcp-fb:120 ccm fir	[RFC5104]