Internet DRAFT - draft-appsawg-perez-sdcp
draft-appsawg-perez-sdcp
ART Area General Applications C. Perez-Monte, Ed.
Internet-Draft GridTICs - UTN FRM
Intended status: Informational March 21, 2016
Expires: September 22, 2016
SDCP: Streaming Distributed Control Protocol
draft-appsawg-perez-sdcp-00
Abstract
This memorandum describes SDCP, a protocol to control multimedia
streaming in cases where streaming generation should be distributed
to improve performance. This is especially useful for Human-Things
streams. Usually, real time applications such as virtual reality
generate a user-controlled multimedia streaming. This is a time
continuous data flux that could be divided spatially to distribute
processing, memory or network resources. This protocol does not
describe streaming communication, but the control of each single
streaming generation in a best-effort by many nodes or things.
Status of This Memo
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3
1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3
2. Distributed Scheme . . . . . . . . . . . . . . . . . . . . . 4
3. SDCP Constant . . . . . . . . . . . . . . . . . . . . . . . . 5
3.1. Multicast Addressing . . . . . . . . . . . . . . . . . . 5
3.2. UDP Ports . . . . . . . . . . . . . . . . . . . . . . . . 5
4. SDCP Format . . . . . . . . . . . . . . . . . . . . . . . . . 5
4.1. General DB Header . . . . . . . . . . . . . . . . . . . . 5
4.2. Specific SDS Header . . . . . . . . . . . . . . . . . . . 7
4.3. Payload . . . . . . . . . . . . . . . . . . . . . . . . . 8
5. Identificators Format . . . . . . . . . . . . . . . . . . . . 8
5.1. SDS index . . . . . . . . . . . . . . . . . . . . . . . . 8
5.2. Node index . . . . . . . . . . . . . . . . . . . . . . . 8
6. Payload types . . . . . . . . . . . . . . . . . . . . . . . . 8
7. Streaming considerations . . . . . . . . . . . . . . . . . . 8
7.1. Streaming protocols . . . . . . . . . . . . . . . . . . . 8
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 8
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9
10. Security Considerations . . . . . . . . . . . . . . . . . . . 9
11. References . . . . . . . . . . . . . . . . . . . . . . . . . 9
11.1. Normative References . . . . . . . . . . . . . . . . . . 9
11.2. Informative References . . . . . . . . . . . . . . . . . 9
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 10
1. Introduction
Usually, the amount of information transmitted from human to computer
is very small. Such is the case of information generated by input
devices, for example, keyboards, mouses or touch screens. On the
contrary, the amount of information transmitted from computer to
human is big. This is increasing over time. Such is the case of
information generated by output devices, for example, computer
monitors or cellphone screens. Furthermore, the hardware resources
such as data processing, network bandwidth or storage are too big.
In many applications, human-to-computer control data is required to
generate computer-to-human data, such as virtual reality. In this
way, human-to-computer control data may be sending to many nodes in
multicast method by best-effort delivery and processing.
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Streaming Distributed Control Protocol (SDCP) is an application-level
protocol for control of streaming distributed generation. SDCP is
built on the User Datagram Protocol (UDP) [RFC0768], which provides a
connection less transport mechanism. SDCP provides the complete
information for proper streaming generation. Other mechanism have
been specified to transmit multimedia streaming, including the Real
Time Streaming Protocol (RTSP) [RFC2326]. The SDCP is not meant to
displace this mechanism but rather complement it.
1.1. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
1.2. Terminology
Some clarifications and additional definitions follow:
o Multimedia Streaming: It is a group of successive multimedia real-
time data blocks in the time. A real-time data block can be an
audio level for multimedia audio streaming or a frame for
multimedia video streaming. Successive blocks of multimedia
streaming must be ordered in time.
o Data Block (DB): Data portion of stream with the same shared time
slot.
o Spatial Data Segment (SDS): Spatial Data segment is subdivision or
partition of each Data block to distributed generation. These
fragments can be spatial fragment of render image or audio wave
channel.
o Processor nodes: These nodes generate the multimedia streaming
under a distributed scheme.
o Administrator Node: This node controls multimedia streaming
generation by periodically sending streaming control to the
processor nodes.
o Integrator node: This node receives multimedia streaming from
Processor nodes to display this to a human receptor.
Integrator and Administrator nodes are the human-side and Processor
nodes are the things-side of the communication system.
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2. Distributed Scheme
Figure 1 shows scheme of a distributed stream generation system.
Each processor node has processing, bandwidth or storing resources
required for partial stream generation.
+------------------------------------------------------------------+
|Remote Administrator Node |
+------------------------------------------------------------------+
| Multicast SDCP data communication
V
+---------------++---------------++---------------++---------------+
|Local Proc Node||Local Proc Node||Local Proc Node||Local Proc Node|
+---------------++---------------++---------------++---------------+
||Uncompressed stream communication
\/
+--------------------------------++--------------------------------+
| Local Integrator Node || Local Integrator Node |
+--------------------------------++--------------------------------+
||Compressed stream communication
\/
+------------------------------------------------------------------+
| Remote Human Receptors |
+------------------------------------------------------------------+
Distributed Scheme.
Figure 1
Administrator Node sends periodically SDCP multicast control
datagrams to Processor Nodes. The use of multicast is mandatory to
select processor group id. The amount of SDCP datagrams should be
sufficient to compensate losses and to allow real-time operation.
These losses may occur by delivery problems or ignored by processor
nodes. Administrator Node MAY assign different Processor Node for
processing each SDS.
Each unoccupied Processor Node receive SDCP datagrams. Occupied
Processor Node SHOULD ignore SDCP datagrams. Each Processor Node
generates stream portion through the use of more current SDCP control
data. This generated stream is sent to appropriate Integrator Node.
Integrator Node receives stream portion unicast communication. All
the stream portion received are integrated in a single stream that is
sent to remote human receptors or locally visualized.
Administrator Node MAY assign different destination Integrator Node
for each SDS. Each integrator node MAY receive multiple streams, a
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same DB or multiple/single SDS of multiple Processor Node. However,
each SDS is assigned to only one Integrator node. While that
different SDS of same stream MAY be assigned to send these to
different integrator nodes, each SDS of same stream MUST NOT be sent
to more than only one Integrator node.
3. SDCP Constant
TO DO
3.1. Multicast Addressing
TO DO
3.2. UDP Ports
TO DO
4. SDCP Format
Main SDCP format is shown in figure 2.
+-------------------+---------------------+--------+
| General DB Header | Specific SDS Header | Payload|
+-------------------+---------------------+--------+
SDCP Format.
Figure 2
o General DB Header: 224-bits length field. This header is
required. Identifies fields from all the DB.
o Specific SDS Header: 128-bits length field. This header is
optional. Identifies fields from specific SDS. If this header is
not present, all SDS of same DB SHOULD be treated equally.
o Payload: Variable-length field. Stream Control Data.
4.1. General DB Header
DB Header is required.
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0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|control data type|M| RD | Stream ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| Time stamp (64 bits) |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SDCP Counter |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Var DB Counter |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| No Var DB Counter |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Payload plus opt header length| Next Header Counter |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
DB Header Format.
Figure 3
Processor Node or Processor Node Group id is determined by multicast
destination address of ip stack.
Control data type: 8-bit selector. Type of control streaming
generation data. Types are defined in accordance with specific
requirement of application. E.g. virtual reality, game or video
streaming, drone controller application, etc.
Control data mode: 1-bit selector. Instant or Historical Mode.
0 - Instant Mode
1 - Historical Mode
RD: 3-bit selector. Reserved for future use.
Stream ID: 20-bit unsigned integer. Multimedia Stream data
identificator.
Time stamp: 64-bits unsigned fixed-point. It includes a 32-bit
unsigned seconds field spanning 136 years and a 32-bit fraction field
resolving 232 picoseconds such as RFC 5905 [RFC5905]. This 64-bit
timestamp format is used in General DB header and payload.
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SDCP Counter: 32-bit unsigned integer. Total number of SDCP
datagrams sent.
Var DB Counter: 32-bit unsigned integer. Total number of SDCP
datagrams sent with control data changes.
No Var DB Counter: 32-bit unsigned integer. Total number of SDCP
datagrams sent from last control data change.
Payload plus opt header length: 16-bit unsigned integer. Length of
Payload, in 16-octet units.
Next Header Counter: 16-bit unsigned integer. Number of Optional SDS
Headers.
4.2. Specific SDS Header
SDS header is optional. This header specifies SDS allocation to
nodes. Two functions are defined. On the one hand, this header MAY
determine which SDS data are assigned to generate by processor node.
On the other hand, this header MAY determine which SDS data are
assigned to send from processor node to integrator node.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| SDS group ID (64 bits) |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| Node group ID (64 bits) |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
SDS Header Format.
Figure 4
SDS group ID: 64-bit selector. Identifies individual SDS or SDS
group for allocation to nodes.
Node group ID: 64-bit selector. Identifies integrator or processor
node for its interface identifier from IPv6 unicast destination
address or identifies processor node group for its low-order 64 bits
of an IPv6 multicast destination address such as IP Version 6
Addressing Architecture [RFC2373]. Allocated Processor Node MUST
process all SDS assigned in SDS group ID and MUST NOT process SDS not
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assigned. Non-allocated Processor Node MAY process all SDS. SDS not
assigned to any Integrator Node MUST be sent to Default Integrator
Node. Similarly, SDS assigned more than one Integrator Node MUST be
sent only to Default Integrator Node.
4.3. Payload
Payload data format is specified in control data type field of
general header. This field determine in virtual reality applications
variables such as camera positions, light positions, etc.
Two modes are supported.
Instant Mode: Last change control data is only sent.
Historical Mode: All changes control data are sent.
Types of control data: TO DO.
5. Identificators Format
TO DO
5.1. SDS index
TO DO
5.2. Node index
TO DO
6. Payload types
TO DO
7. Streaming considerations
TO DO
7.1. Streaming protocols
TO DO
8. Acknowledgements
I would like to thank the resources and support of GRIDTICS and
LICPaD of the Universidad Tecnologica Nacional Regional Mendoza (UTN
FRM), LIDIC of the Universidad Nacional de San Luis (UNSL), the Joint
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Laboratory for System Evaluation (JLSE) at Argonne National
Laboratory and Dept. of Bioengineering, Dept. of Biomedical and
Health Information Sciences to the University of Illinois at Chicago
(UIC). Especially, I am deeply grateful to Gustavo Mercado,
Christian O'Flaherty, Ines Robles and Gabriel Montenegro for their
support.
9. IANA Considerations
This memo includes no request to IANA.
10. Security Considerations
TO DO
11. References
11.1. Normative References
[RFC0768] Postel, J., "User Datagram Protocol", STD 6, RFC 768,
DOI 10.17487/RFC0768, August 1980,
<http://www.rfc-editor.org/info/rfc768>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>.
11.2. Informative References
[RFC2326] Schulzrinne, H., Rao, A., and R. Lanphier, "Real Time
Streaming Protocol (RTSP)", RFC 2326,
DOI 10.17487/RFC2326, April 1998,
<http://www.rfc-editor.org/info/rfc2326>.
[RFC2373] Hinden, R. and S. Deering, "IP Version 6 Addressing
Architecture", RFC 2373, DOI 10.17487/RFC2373, July 1998,
<http://www.rfc-editor.org/info/rfc2373>.
[RFC5905] Mills, D., Martin, J., Ed., Burbank, J., and W. Kasch,
"Network Time Protocol Version 4: Protocol and Algorithms
Specification", RFC 5905, DOI 10.17487/RFC5905, June 2010,
<http://www.rfc-editor.org/info/rfc5905>.
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Author's Address
Cristian Federico Perez-Monte (editor)
GridTICs - UTN FRM
Rodriguez 273 Cuarto Piso Bloque Dpto Electronica
Ciudad de Mendoza, Mendoza M5502AJE
AR
Phone: +54 261 524 4563
Email: cristian.perez@gridtics.frm.utn.edu.ar
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