Internet DRAFT - draft-xia-avt-mpeg2ts-preamble

draft-xia-avt-mpeg2ts-preamble






Audio/Video Transport                                            P. Yang
Internet-Draft                                                    F. Xia
Intended status: Standards Track                                   X. Wu
Expires: April 28, 2011                    Huawei Technologies Co., Ltd.
                                                        October 25, 2010


          Preamble Acquisition of MPEG2-TS Multicast Sessions
                 draft-xia-avt-mpeg2ts-preamble-04.txt

Abstract

   The ITU-T Rec. H.222.0 | ISO/IEC 13818-1 Transport Stream (MPEG2-TS)
   addresses the combining of one or more elementary streams of video
   and audio, as well as other data, into single or multiple streams
   which are suitable for storage or transmission.  The necessary and
   sufficient information contained in the Program Specific
   Information(PSI) tables to demultiplex and present programs must be
   acquired before a RTP receiver can process any data received in
   MPEG2-TS.  In this document, a Retransmission Server is specified to
   deliver MPEG2-TS preamble prior to unicast burst RTP packets.  The
   Retransmission Server caches raw RTP packets with MPEG2-TS preamble
   information, and sends them to the RTP receiver which initiates rapid
   acquisition of MPEG2-TS multicast sessions.

Status of this Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
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   This Internet-Draft will expire on April 28, 2011.

Copyright Notice

   Copyright (c) 2010 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal



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   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
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Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Terminology  . . . . . . . . . . . . . . . . . . . . . . . . .  4
   3.  Abbreviation . . . . . . . . . . . . . . . . . . . . . . . . .  4
   4.  Overview of MPEG-2 Transport Streams . . . . . . . . . . . . .  5
   5.  Preamble Acquisition of MPEG2-TS Multicast Sessions  . . . . .  8
     5.1.  Overview . . . . . . . . . . . . . . . . . . . . . . . . .  8
     5.2.  MPEG2-TS Preamble Structure  . . . . . . . . . . . . . . . 11
     5.3.  The Implementation of MPEG2-TS Preamble  . . . . . . . . . 12
       5.3.1.  PCR information  . . . . . . . . . . . . . . . . . . . 13
       5.3.2.  PES header information . . . . . . . . . . . . . . . . 13
       5.3.3.  Discontinuity indicator information  . . . . . . . . . 14
       5.3.4.  Elementary Video Encoding Information  . . . . . . . . 14
       5.3.5.  Other extended PSIs Information  . . . . . . . . . . . 15
     5.4.  RTP Header of reconstructing new RTP packets . . . . . . . 15
     5.5.  Message Flow . . . . . . . . . . . . . . . . . . . . . . . 16
   6.  The timing of the MPEG2-TS Preamble  . . . . . . . . . . . . . 19
   7.  Security Considerations  . . . . . . . . . . . . . . . . . . . 20
   8.  Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 20
   9.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 21
     9.1.  Normative References . . . . . . . . . . . . . . . . . . . 21
     9.2.  Informational References . . . . . . . . . . . . . . . . . 22
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 23

















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1.  Introduction

   Real-time multimedia multicast flows usually carry streams of inter-
   related data.  Certain information must first be acquired by the
   receivers to start processing multimedia data sent in the multicast
   session.  [I-D.ietf-avt-rapid-acquisition-for-rtp] refers to this
   information as Reference Information.  Part of the Reference
   Information is conventionally sent periodically in the multicast
   session and usually consists of items such as a description of the
   schema for the rest of the data, references to which data to process,
   encryption information including keys, as well as any other
   information required to process the data in the primary multicast
   stream.

   The ITU-T Rec. H.222.0 | ISO/IEC 13818-1 Transport Stream[MPEG2-TS]
   is a stream definition which is tailored for communicating or storing
   one or more programs of coded data according to ITU-T Rec. H.262 |
   ISO/IEC 13818-2 and ISO/IEC 13818-3 and other data in environments.
   The MPEG2-TS is already widespread in the digital broadcasting and
   IPTV services over both terrestrial and satellite networks, not only
   in Europe but also in Asia and North America.  When the primary
   multicast stream is using an encapsulation method of MPEG2-TS over
   RTP that multiplexes video and audio content, together with ancillary
   metadata, and produces a synchronized multiplexed stream, the
   receiver must first acquire the necessary and sufficient information
   before demultiplexing and decoding an incoming MPEG2-TS.  However,
   these necessary and sufficient information of MPEG2 Transport Stream
   does not reside in MPEG2-TS contiguously and is usually dispersed
   over a large period of time.  When the receivers starts receiving the
   Reference Information from the random access point as detailed in
   [I-D.ietf-avt-rapid-acquisition-for-rtp], the Reference Information
   of MPEG2-TS cannot be completely received particularly the MPEG2-TS
   Program Specific Information (PSI) tables so that the receivers
   cannot demultiplex and decode correctly.  In order to demultiplex and
   decode correctly for the receivers, parts of the Reference
   Information of MPEG2-TS, extracted from MPEG2 transport stream
   packets prior to the random access point(RAP) over a long period(
   even several previous Reference Information away), must be acquired
   before demultiplexing and decoding.  In this document, we refers to
   this information as MPEG2-TS preamble.

   This document describes how to convey this preamble information to
   the receiver before the unicast burst stream defined in RAMS
   [I-D.ietf-avt-rapid-acquisition-for-rtp].







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2.  Terminology

   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 [RFC2119].


3.  Abbreviation

   The following abbreviations are used in this document:









































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      CAT:       Conditional Access Table

      ECM:       Entitlement Control Message

      EMM:       Entitlement Management Message

      GoP:       Group of Picture

      IDR:       Instantaneous Decoding Refresh

      IPMP:      Intelligent Property Management and Protection

      MP2T:      MPEG2 Transport Stream

      MPEG2-TS:  MPEG2 Transport Stream

      NAL:       Network Abstract Layer

      NIT:       Network Information Table

      PAT:       Program Association Table

      PCR:       Program Clock Reference

      PES:       Packetized Elementary Stream

      PMT:       Program Map Table

      PPS:       Picture Parameter Set

      PS:        Private Section

      PSI:       Program Specific Information

      RAP:       Random Access Point

      SEI:       Supplemental Enhancement Information

      SPS:       Sequence Parameter Set

      TSDT:      Transport Stream Description Table


4.  Overview of MPEG-2 Transport Streams

   ITU-T Rec. H.222.0 | ISO/IEC 13818-1 Transport Stream addresses the
   combining of one or more elementary streams of video and audio, as
   well as other data, into single or multiple streams which are



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   suitable for storage or transmission.  Systems coding follows the
   syntactical and semantic rules imposed by this Specification and
   provides information to enable synchronized decoding of decoder
   buffers over a wide range of retrieval or receipt conditions.

   The basic multiplexing approach for single video and audio elementary
   streams is illustrated in Figure 1.  The video and audio data is
   encoded as described in ITU-T Rec. H.262 | ISO/IEC 13818-2 and ISO/
   IEC 13818-3.  The resulting compressed elementary streams are
   packetized to produce Packetized Elementary Streams(PES) packets.


  video    +-------------+    +----------+ Video PES +---------+
  input--->|Video Encoder|--->|Packetizer|---------->|         |
           +-------------+    +----------+           |         |
                                                     |         |
  Audio    +-------------+    +----------+ Audio PES |MPEG-2   |
  input--->|Audio Encoder|--->|Packetizer|---------->|         | Network
           +-------------+    +----------+           |Transport|---->
                                                     |         |
         Optional Application Data(e.g subtitle)---> |Stream   |
                                                     |         |
                    Program Specific Information---> |Mux      |
                                                     |         |
                                         ... ...---> |         |
                                                     +---------+

        Figure 1: The overview of MPEG-2 Transport Streams

   The MPEG2 Transport Stream coding layer allows one or more programs
   to be combined into a single stream.  Data from each elementary
   stream are multiplexed together with information that allows
   synchronized presentation of the elementary streams within a program.

   A Transport Stream consists of one or more programs.  Audio and video
   elementary streams consist of access units(A coded representation of
   a presentation unit).

   Elementary Stream data is carried in PES packets.  A PES packet
   consists of a PES packet header followed by packet data.  PES packets
   are inserted into Transport Stream packets.  The first byte of each
   PES packet header is located at the first available payload location
   of a Transport Stream packet.

   Transport Stream packets begin with a 4-byte prefix, which contains a
   13-bit Packet ID (PID).  The PID identifies, via the Program Specific
   Information (PSI) tables, the contents of the data contained in the
   Transport Stream packet.  Transport Stream packets of one PID value



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   carry data of one and only one elementary stream.  The PSI tables are
   carried in the Transport Stream.  There are Six PSI tables shown in
   table 2.28 of H.222.0(2006) (There were only the first four PSI
   tables in the ITU-T Rec. H.222.0(2000 E) | ISO/IEC 13818-1:2000 E):

           o Program Association Table;
           o Program Map Table;
           o Conditional Access Table;
           o Network Information Table;
           o Transport Stream Description Table;
           o IPMP Control Information Table.

   These tables contain the necessary and sufficient information to
   demultiplex and present programs.  Program Association Table contains
   the PIDs of NIT and PMT, what's more, the private section in
   Transport Stream packets with a PID value is designated as a Program
   Map Table PID in the Program Association Table.  The Program Map
   Table provides among other information, which PIDs, and therefore
   which elementary streams are associated to form each program.  This
   table also indicates the PID of the Transport Stream packets which
   carry the PCR for each program.  The Conditional Access Table shall
   be present if scrambling is employed.  The Network Information Table
   is optional and its contents are not specified by the ITU-T Rec.
   H.222.0 | ISO/IEC 13818-1.  Transport Stream Description Table(TSDT)
   has 256(an 8-bit field) transport stream description elements shown
   in Table 2-45 - Program and program element descriptors of
   H.222.0(2006).  The IPMP Control Information Table shall be present
   if IPMP as described in ISO/IEC 13818-11 is used by any of the
   components in the ITU-T Rec. H.222.0 | ISO/IEC 13818-1 stream.

   Except for these PSI tables, ETSI DVB EN 300 468 and ATSC Document
   A/69 also define some extended PSIs and PSIP information.  Other
   standard organizations and operators may define some extended PSI
   information.  We need to consider which PSI information is necessary
   to demultiplex and decode.

   In this document, terminologies PSI and MPEG2-TS preamble are
   interchangeable.  Media including video, audio and text in an
   MPEG2-TS is self describing, and the receiver must parse certain
   control information in the PAT, CAT and PMT tables (i.e., PSI)
   contained in the transport stream in order to know how to parse the
   rest of the stream (i.e., to find the audio and video elementary
   streams, private data and the encryption information for a given
   program).  This document specifies a mechanism to acquire PSI rapidly
   when a receiver joins in a MPEG2-TS multicast session.






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5.  Preamble Acquisition of MPEG2-TS Multicast Sessions

5.1.  Overview

   In video coding, a group of picture (GOP) specifies the order in
   which intra-frame and inter-frames are arranged.  The GOP is a group
   of successive pictures within a coded video stream.  Each coded video
   stream consists of successive GOPs.  A GOP always begins with a
   Random Access Point (RAP)- an intra-frame(e.g.  IDR-frame).
   Afterwards several inter-frames(e.g.  P-frame) follow.  The Intra-
   frame is a reference frame which contains the full image which
   represents a fixed image and which is independent of other picture
   types and do not require any additional information to reconstruct
   it.  The inter-frame is a prediction frame which contains motion-
   compensated difference information from the preceding Intra-frame or
   other inter-frames in a video compression stream which is expressed
   in terms of one or more neighboring frames.

   When a receiver joins a primary multicast session, it does not have
   control over what point in the flow is currently being transmitted,
   it needs to wait until the next RAP and other necessary and
   sufficient information for demultiplexing and decoding (which we
   refer to as the Reference Information in the [I-D.ietf-avt-rapid-
   acquisition-for-rtp]) shows up in the multicast stream before it can
   start decoding.  In order to reduce the acquisition delay when the
   RTP receiver joins a multicast session at a random point in time,
   RAMS in the [I-D.ietf-avt-rapid-acquisition-for-rtp] introduces the
   method as Unicast- based Rapid Acquisition of Multicast RTP Sessions
   illustrated in Figure 2 where an auxiliary unicast RTP session
   carrying the Reference Information to the receiver precedes/
   accompanies the primary multicast stream.  This unicast RTP flow is
   transmitted at a faster than natural rate to further accelerate the
   acquisition.

   In MPEG2 transport stream case, the Reference Information is often
   not contiguous in the flow but dispersed over a large period, it even
   spans several GOPs.  It is often distributed in different RTP packets
   with other MPEG2-TS packets which are not part of the reference
   information.  Figure 2 illustrates an RTP stream where PAT, PMT and
   ECM information distribute in the three different RTP packets.











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 ...
 RTP SN(28255) PAT(TS1)
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |RTP(H)|TS1(188)|TS2(188)|TS3(188)|TS4(188)|TS5(188)|TS6(188)|TS7(188)|
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 ...
 RTP SN(28266) PMT(TS6)
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |RTP(H)|TS1(188)|TS2(188)|TS3(188)|TS4(188)|TS5(188)|TS6(188)|TS7(188)|
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 ...
 RTP SN(28291) ECM(TS4)
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |RTP(H)|TS1(188)|TS2(188)|TS3(188)|TS4(188)|TS5(188)|TS6(188)|TS7(188)|
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 ...
 RTP SN(28301)(Random Access point: IDR-frame(TS6)
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |RTP(H)|TS1(188)|TS2(188)|TS3(188)|TS4(188)|TS5(188)|TS6(188)|TS7(188)|
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      Figure 2 Original RTP sequence only with PAT, PMT and ECM

   In Figure 2 the TS1 packet of RTP packet with sequence number 28255
   is a PAT packet.  The TS6 packet of RTP packet with sequence number
   28266 is a PMT packet.  The TS4 packet of RTP packet with sequence
   number 28291 is an ECM packet.  TS6 of RTP packet with sequence
   number 28301 is a beginning of a Random Access point of IDR-frame.
   The Reference Information for this RTP sequence starting at RTP
   sequence number 28301 needs the PAT information in the RTP SN 28255,
   the PMT information of in the RTP SN 28266 and the ECM information of
   in the RTP SN 28291.  The process is now to extracts the PSI
   information and to build a new RTP packet illustrated in Figure 3
   where PAT is in TS1, PMT in TS2 and ECM in TS3.


 RTP SN(xxx) PAT(TS1),PMT(TS2),ECM(TS3)
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |RTP(H)|TS1(188)|TS2(188)|TS3(188)|
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 RTP(RFC4588) SN(28301)(Random Access point: IDR-frame(TS6)
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |RTP(H)|TS1(188)|TS2(188)|TS3(188)|TS4(188)|TS5(188)|TS6(188)|TS7(188)|
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 ...
              Figure 3 Preamble MPEG2-TS RTP sequence

   In MPEG2-TS PSI information, PAT, PMT, and ECM(ECM shall be present



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   if scrambling is employed) are always present.  Other reference
   information enabling automatic configuration of the receiver to
   demultiplex and decode the various streams of programs within the
   multiplex are optionally provisioned depending on different policies
   and demand of demultiplexing and decoding.  For example, the
   Conditional Access Table shall be present if scrambling is employed.
   The IPMP Control Information Table shall be present if IPMP as
   described in ISO/IEC 13818-11 is used by any of the components in the
   ITU-T Rec. H.222.0 | ISO/IEC 13818-1 stream.  The Reference
   information (Time and Date Table (TDT), Service Description Table
   (SDT),etc.) in the ETSI DVB EN 300 468 shall be optionally present to
   provide identification of services and events for the user.  The
   following RTP sequence illustrated in Figure 4 includes more PSI
   table elements.

 ...
 RTP SN(10739) CAT(TS2)
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |RTP(H)|TS1(188)|TS2(188)|TS3(188)|TS4(188)|TS5(188)|TS6(188)|TS7(188)|
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 ...
 RTP SN(10758) PAT(TS3)
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |RTP(H)|TS1(188)|TS2(188)|TS3(188)|TS4(188)|TS5(188)|TS6(188)|TS7(188)|
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 ...
 RTP SN(10796) PMT(TS3)
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |RTP(H)|TS1(188)|TS2(188)|TS3(188)|TS4(188)|TS5(188)|TS6(188)|TS7(188)|
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 ...
 RTP SN(10829) ECM(TS2)
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |RTP(H)|TS1(188)|TS2(188)|TS3(188)|TS4(188)|TS5(188)|TS6(188)|TS7(188)|
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 ...
 RTP SN(10834) PAT(TS4)
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |RTP(H)|TS1(188)|TS2(188)|TS3(188)|TS4(188)|TS5(188)|TS6(188)|TS7(188)|
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 ...
 RTP SN(10851) NIT(TS5)
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |RTP(H)|TS1(188)|TS2(188)|TS3(188)|TS4(188)|TS5(188)|TS6(188)|TS7(188)|
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 ...
 RTP SN(10872) PMT(TS3)
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+



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 |RTP(H)|TS1(188)|TS2(188)|TS3(188)|TS4(188)|TS5(188)|TS6(188)|TS7(188)|
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 ...
 RTP SN(10910) PAT(TS2)
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |RTP(H)|TS1(188)|TS2(188)|TS3(188)|TS4(188)|TS5(188)|TS6(188)|TS7(188)|
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 ...
 RTP SN(10912) SDT(TS2),TDT(TS7)
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |RTP(H)|TS1(188)|TS2(188)|TS3(188)|TS4(188)|TS5(188)|TS6(188)|TS7(188)|
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 RTP SN(10913)(Random Access point: IDR-frame(TS1),ECM(TS2)
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |RTP(H)|TS1(188)|TS2(188)|TS3(188)|TS4(188)|TS5(188)|TS6(188)|TS7(188)|
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Figure 4 Original RTP sequence with PAT, PMT, ECM, CAT, SDT...

   Figure 5 shows an example of MPEG2-TS preamble providing the RTP
   sequence with PAT, PMT ECM, NIT, CAT, SDT and TDT.

 SN(xxx) PAT(TS1),PMT(TS2),ECM(TS3),NIT(TS4),CAT(TS5),SDT(TS6),TDT(TS7)
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |RTP(H)|TS1(188)|TS2(188)|TS3(188)|TS4(188)|TS5(188)|TS6(188)|TS7(188)|
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 RTP(RFC4588) SN(10913)(Random Access point: IDR-frame(TS1),ECM(TS2)
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |RTP(H)|TS1(188)|TS2(188)|TS3(188)|TS4(188)|TS5(188)|TS6(188)|TS7(188)|
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

          Figure 5 Preamble MPEG2-TS RTP sequence

5.2.  MPEG2-TS Preamble Structure

   The order of PSI information need to be considered when rebuilding
   RTP packets.  Except for some fixed PIDs(0x0000 for PAT, 0x0001 for
   CAT, 0x0002 for Transport Stream Description Table, 0x0003 for IPMP
   Control Information Table), other PIDs are inherited from those fixed
   PIDs.  For example the PID of PMT is inherited from PAT.  The PID of
   ECM is inherited from CAT, or PMT, or Transport Stream Description
   Table.  The PIDs of Private_Section are designated as a Program Map
   Table PID in the Program Association Table.  Figure 6 shows the
   inheritance of PAT and CAT.







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             +-+-+                                     +-+-+
             |PAT| PID(0x0000)                         |CAT| PID(0x0001)
             +-+-+                                     +-+-+
               |                                         |
     --------------------                           ------------
     |         |        |                          |           |
   +-+-+     +-+-+    +-+-+                      +-+-+       +-+-+
   |NIT|     |PMT|    | PS| Private Section      |ECM|       |EMM|
   +-+-+     +-+-+    +-+-+                      +-+-+       +-+-+
               |
           ---------
          |         |
        +-+-+     +-+-+
        |ECM|     |EMM|
        +-+-+     +-+-+

                   Figure 6 The inheritance of PSI PIDs

5.3.  The Implementation of MPEG2-TS Preamble

   The MPEG2-TS Preamble Information of the Reference Information is
   mainly composed of essential PSIs which affect the demultiplexing and
   decoding, and also include PES header and elementary coded video
   information if the Random Access Point-Intra-frame hasn't included
   this information.  There are dozens of PSI tables of MPEG2-TS which
   include PAT, PMT, PCR, CAT, ECM/EMM, Transport Stream Description
   Elements of the 8-bit field, IPMP Control Information Table, Private
   Section.  Except for these PSI tables defined in the ITU-T Rec.
   H.222.0 | ISO/IEC 13818-1, both ETSI DVB EN 300 468 and ATSC Document
   A/69 define some extended PSIs and PSIP information.  Other standard
   organizations and operators may define some extended PSI information.
   The implementation need to consider which PSI information affect on
   the start-up of RAMS.

   The MPEG2-TS PSI information are not present simultaneously, and may
   be distributed in different RTP packets over a large period of time.
   They can be part of the preamble information or the RTP_Rx can
   receive them later from the unicast burst and the multicast stream.
   The important elements are the PAT, PMT, PCR and ECM/EMM and the
   implementation can decide which elements to include in the Preamble
   stream.  Nevertheless, this document doesn't limit the implementation
   and it cab decide which are the important elements of PSIs
   information.

   In order to efficiently transmit the MPEG2-TS preamble information
   and not affect the start-up of RAMS, the implementation reconstructs
   new RTP packets by using the raw MPEG2-TS preamble information
   extracted from the MPEG2-TS packets sequence of the primary multicast



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   stream.  Figure 7 illustrates the detailed process of reconstructing
   a RTP packet of MPEG2-TS preamble.  Nevertheless, in the process of
   reconstruction, it is necessary to keep the MPEG2-TS Preamble Order
   described in the section 5.2 MPEG2-TS Preamble Structure in order to
   guarantee the demultiplexing and decoding correctly.

     +-+-+-+-+-+-+-+-+-+-+-+    +-+-+-+-+-+-+-+-+-+-+-+
  ...|RTP(H)|...TS2(ECM)...| ...|RTP(H)|...TS5(PAT)...|...
     +-+-+-+-+-+-+-+-+-+-+-+    +-+-+-+-+-+-+-+-+-+-+-|
                  |                          |
          +------ +                          |
          |    +-----------------------------+
          |    |   +-+-+-+-+-+-+-+-+-+-+-+    +-+-+-+-+-+-+-+-+-+-+-+
          |    |...|RTP(H)|...TS3(PMT)...| ...|RTP(H)|...TS5(PCR)...|...
          |    |   +-+-+-+-+-+-+-+-+-+-+-+    +-+-+-+-+-+-+-+-+-+-+-+
          |    |                |                          |
          |    |            +---+                     +----+
          +----|------------|------------+            |
               |            |            |            |
   SN(xxx)     v            v            v            v
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |RTP (H)|TS1-PAT(188)|TS2-PMT(188)|TS3-ECM(188)|TS4-PCR(188)|
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      Figure 7 RTP Reconstruction Process of MPEG2-TS Preamble

5.3.1.  PCR information

   There are two ways to transmit PCR information in MPEG2-TS stream.
   One is an independent PCR PID where the discontinuity indicator value
   is set to '0'.  The other is by having the PCR information as the
   adaptation field inserted in TS packets of video and share the same
   PID as the video stream.  Whether the PCR information is an
   independent PCR PID or shares a TS packet with video, the PCR
   information shall be transmitted as an MPEG2-TS preamble.

5.3.2.  PES header information

   Normally the first TS packet of a Random Access Point (RAP)-intra-
   frame contains a PES Header following TS header, and then by video
   coded frame data.  As is shown in Figure 8.

   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |TS Header| PES Header |         video coded frame data         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

             Figure 8 The first TS packet of RAP with PES Header




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   However, in some cases of MPEG2-TS, several video frames share one
   PES header.  It can happen that the first TS packet of the reference
   information of Random Access Point doesn't include PES header.  As is
   shown in Figure 9.

   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |TS Header|                video coded frame data               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

             Figure 9 The first TS packet of RAP without PES Header

   The PES Header is very important for the demultiplexing, RTP
   Receivers cannot demultiplex and decode correctly the MPEG2-TS stream
   before PES header.  In this case, the PES Header must be an MPEG2-TS
   preamble information transmitted before RAMS.

5.3.3.  Discontinuity indicator information

   In some cases, the field of discontinuity indicator of PSI
   information is set to '1' which indicates that the discontinuity
   state is true.  When the discontinuity state is true in PSI packet of
   a PID not designated as a PCR_PID, the continuity counter in that
   packet may be discontinuous with respect to the previous Transport
   Stream packet of the same PID.  After the occurrence of a
   discontinuity indicator set to '1' in the Transport Stream packets of
   the same PID which contains PSI information, these discontinuous
   Transport Stream packets all shall be transmitted as the MPEG2-TS
   preamble, otherwise it shall not be constructed in such a way that
   discarding such a packet will cause the loss of PES packet payload
   data or PSI data.  When reconstructing these Transport Stream packets
   of PSI information, it is necessary to keep their original order.

5.3.4.  Elementary Video Encoding Information

   Elementary Video Encoding Information (e.g.  SPS(Sequence Parameter
   Set)/PPS(Picture Parameter Set) /SEI(Supplemental Enhanced
   Information in MPEG4/H.264 codec, Video Sequence information in MPEG2
   codec, Sequence and Entry-Point information in VC-1 codec, etc.) is
   very important for the video decoding.  Like the PES header, it may
   happen that several video frames share the elementary video coded
   information in MPEG2 transport stream so that an intra-frame may not
   contain elementary video encoding information.  At this time,
   elementary video coded information shall be transmitted as part of
   the MPEG2-TS preamble.

   The Sequence Parameter Set is a kind of NAL unit and contains syntax
   elements that apply to zero or more entire coded video sequences as
   determined by the content of a seq_parameter_set_id syntax element



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   found in the picture parameter set referred to by the
   pic_parameter_set_id syntax element found in each slice header.  The
   Picture Parameter Set is also a kind of NAL unit and contains syntax
   elements that apply to zero or more entire coded pictures as
   determined by the pic_parameter_set_id syntax element found in each
   slice header.  The Video Sequence information (e.g.  Sequence header,
   Extension and user data, Group of pictures header, etc.) is the
   highest syntactic structure of coded video bit streams and contains
   with a sequence header which may optionally be followed by a group of
   pictures header and then by one or more coded frames.  The Sequence
   and Entry-Point information (e.g. sequence-level header, entry-point
   header ) are required for the decoder and shall be sent view the
   MPEG2-TS premable.

5.3.5.  Other extended PSIs Information

   Except for essential PSIs information which affect on the
   demultiplexing and decoding, other PSIs are recommended to be
   transmitted if they don't exist after the reference information of
   random access point for a long time.

5.4.   RTP Header of reconstructing new RTP packets

   The format of the RTP header of reconstructing new RTP packets is
   specified in RFC 3550 and reprinted in Figure 10 for convenience.
   This RTP payload format for MPEG2-TS preamble uses raw MPEG2-TS
   packets with the Reference Information from the original MPEG2-TS
   packets sequence in a manner consistent with that specification.
       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |V=2|P|X|  CC   |M|     PT      |       sequence number         |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                           timestamp                           |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |           synchronization source (SSRC) identifier            |
      +=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+
      |            contributing source (CSRC) identifiers             |
      |                             ....                              |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                    Figure 10 RTP header according to RFC 3550

   The RTP header information to be set according to this RTP payload
   format is set as follows:

   Marker bit (M): 1 bit




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       The Maker bit is set to one if there is only one RTP packet of
       MPEG2-TS preamble.  The last RTP packet of MPEG2-TS preamble is
       set to one, others are set to zero if there are more than one RTP
       packet of MPEG2-TS preamble.

   Sequence number (SN): 16 bits

       The SN is set and used in accordance with RFC 3550.  In order to
       make it easier for the RAMS-I message to convey the sequence
       number of the first message in the unicast channel which is a
       preamble packet the sequence numbers of the MPEG2-TS Preamble
       shall be equal to minus one by the first original sequence number
       of the unicast retransmission RTP packet if there is only one RTP
       packet of MPEG2-TS preamble.  If there are n RTP packets, their
       sequence numbers are equal to minus one, two,..., n by the first
       original sequence number of the unicast retransmission RTP packet
       respectively.  Note that the SSRCs of the preamble stream and the
       unicast burst are different.

   Timestamp: 32 bits

       The RTP timestamp is set to the sampling timestamp of the
       content.  The timestamp of the MPEG2-TS Preamble shares the same
       timestamp space with primary multicast RTP packets, and is set to
       the previous RTP timestamp of the random access point(RAP) which
       is the first original sequence number of the primary multicast
       RTP packet.

   Synchronization Source (SSRC): 32 bits

      The SSRC identifier SHOULD be chosen randomly with collision
      detection, is not likely to choose the same number with primary
      multicast session.

5.5.  Message Flow

   Figure 10 depicts message flows for MPEG2TS Preamble acquisition.  A
   RTP receiver sends a rapid acquisition request for a new multicast
   RTP session to the feedback target address of that session.  This
   RTCP feedback message is defined as the RAMS-Request (RAMS-R) message
   in [I-D.ietf-avt-rapid-acquisition-for-rtp] and MAY also contain
   parameters, such as the bandwidth limit, buffering capacity available
   at the RTP receiver, and so on.

   A retransmission server receives the RAMS-R message and sends an
   RAMS-Information (RAMS-I) message to the RTP receiver.  The first
   RAMS-I message MAY precede the unicast burst or it MAY be sent during
   the burst.  The retransmission server then starts sending unicast



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   MPEG2TS Preamble RTP packets prior to delivering Unicast RTP Burst.

   In this document, a unicast "MPEG2TS Preamble RTP" delivering process
   is added for transporting necessary MPEG2-TS preamble information.
   The unicast MPEG2TS Preamble RTP stream shall be transmitted before
   the Unicast RTP burst, as shown in Figure 10.  The information is
   carried as RFC 2250 [RFC2250] RTP packets.

                  -------------------------
                 | Retransmission  Server  |
    -----------  |  ------   ------------  |   --------    ------------
   | Multicast | | |  FT  | | Burst/Ret. | |  |        |  |    RTP     |
   |  Source   | | |      | |   Source   | |  | Router |  |  Receiver  |
   |           | |  ------   ------------  |  |        |  |  (RTP_Rx)  |
    -----------  |      |         |        |   --------    ------------
     |            -------------------------       |                |
     |                  |         |               |                |
     |-- RTP Multicast ---------->--------------->|                |
     |-. RTCP Multicast -.-.-.-.->-.-.-.-.-.-.-.->|                |
     |                  |         |               |                |
     |                  |         |********************************|
     |                  |         |*      PORT MAPPING SETUP      *|
     |                  |         |********************************|
     |                  |         |               |                |
     |                  |<~~~~~~~~~~~~~~~~~~~~~~~~~ RTCP RAMS-R ~~~|
     |                  |         |               |                |
     |                  |         |********************************|
     |                  |         |* UNICAST SESSION  ESTABLISHED *|
     |                  |         |********************************|
     |                  |         |               |                |
     |                  |         |~~~ RTCP RAMS-I ~~~~~~~~~~~~~~~>|
     |                  |         |               |                |
     |                  |         |... Unicast RTP Burst .........>|
     |                  |         |               |                |
     |                  |<~~~~~~~~~~~~~~~~~~~~~~~~ (RTCP RAMS-R) ~~|
     |                  |         |               |                |
     |                  |         |~~ (RTCP RAMS-I) ~~~~~~~~~~~~~~>|
     |                  |         |               |                |
     |                  |         |               |                |
     |                  |         |               |<= SFGMP Join ==|
     |                  |         |               |                |
     |-- RTP Multicast ------------------------------------------->|
     |-. RTCP Multicast -.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.>|
     |                  |         |               |                |
     |                  |         |               |                |
     |                  |         |<~~~~~~~~~~~~~~~ RTCP RAMS-T ~~~|
     |                  |         |               |                |
     :                  :         :               :                :



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     |                  |         |<.=.= Unicast RTCP Reports .=.=>|
     :                  :         :    (for the unicast session)   :
     |                  |         |               |                |


   :::::::> MPEG2TS Preamble RTP
   -------> Multicast RTP Flow
   .-.-.-.> Multicast RTCP Flow
   .=.=.=.> Unicast RTCP Reports
   ~~~~~~~> Unicast RTCP Feedback Messages
   =======> SFGMP Messages
   .......> Unicast RTP Flow

          Figure 10: Message flows for MPEG2TS Preamble Acquisition

   The SDP[RFC4566] description of the MPEG2-TS Preamble information is
   conveyed in an RAMS session description as defined in [I-D.ietf-avt-
   rapid-acquisition- for-rtp].  Figure 11 shows an SDP example which
   multiplexes the MPEG2-TS Preamble information and an RAMS unicast
   retransmission session based on Section 8.2 of [I-D.ietf-avt-rapid-
   acquisition-for-rtp].






























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           v=0
           o=S1 1122334455 1122334466 IN IP4 rams.example.com
           s=Rapid Acquisition Example with MPEG2-TS Preamble Data
           t=0 0
           a=group:FID 3 4
           a=rtcp-unicast:rsi
           m=video 41000 RTP/AVPF 98
           i=Primary Multicast Stream
           c=IN IP4 233.252.0.2/255
           a=source-filter: incl IN IP4 233.252.0.2 192.0.2.2
           a=rtpmap:98 MP2T/90000
           a=rtcp:41001 IN IP4 192.0.2.1
           a=rtcp-fb:98 nack
           a=rtcp-fb:98 nack ssli
           a=ssrc:123321 cname:iptv-ch32@rams.example.com
           a=mid:3
           m=video 41002 RTP/AVPF 99 100
           i=Unicast Retransmission Stream + Preamble Data
           c=IN IP4 192.0.2.1
           a=rtpmap:99 rtx/90000
           a=rtcp:41003
           a=fmtp:99 apt=98; rtx-time=5000
           a=preamble 100
           a=rtpmap:100 MPEG2TS-Preamble/90000
           a=mid:4

          Figure 11: The SDP description of the MPEG2-TS Preamble
                     information conveying in an RAMS session


6.  The timing of the MPEG2-TS Preamble

   The RTP preamble packets are received by the RTP receiver.

   The preamble needs to be processed correctly by the Transport Stream
   (TS) processor to enable the TS processor to extract and utilize the
   information in the preamble.

   There is a risk that if the preamble is fed immediately to the TS
   processor, some preamble elements may not be processed correctly.  TS
   processors may require a non-trivial amount of time to process each
   element of the preamble, and in these cases the elements of the
   preamble need to be processed in a certain order in order to be
   processed correctly.  The correct processing of any one preamble
   element often depends on completing the processing of all preceding
   elements in the same preamble.  If a preamble element is processed
   too early, there is a risk that the TS processor will not be able to
   process it correctly.  Dependencies may include setting up PAT and



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   PMT, and decryption engines.

   Therefore, in order for the TS processor to process the preamble
   correctly, it may be necessary to pace the processing of the
   preamble.  There are several mechanisms that can be used to pace the
   processing of the preamble appropriately for robust operation.  Two
   such mechanisms are proposed here; others may be possible.

   In this context, the TS processor may be any combination of hardware
   and software on one or multiple processors.

   1.  The RTP stack removes RTP header of the preamble information and
   passes the entire preamble to the TS processor, and the TS processor
   is responsible for processing the preamble information correctly.
   There are various ways that the TS processor might ensure that the
   preamble is processed correctly.  In one approach, software
   associated with the TS processor monitors the time required to
   perform the necessary TS processing operations on each preamble
   element, and paces the processing of each preamble element so as to
   ensure that no preamble element is processed before the preceding
   operations on which it depends have been performed.

   2.  The RTP stack controls the timing of the preamble TS packets sent
   to the TS decoder, or more precisely to a TS cache (buffer) between
   the RTP stack and the TS decoder.  This timing control may include
   inserting dummy TS packets, repeating the TS preamble packets, or
   other means of pacing.  The type and amount of pacing that should be
   applied to each preamble element depends on the specific design and
   timing of the TS processor, and it may depend on the values contained
   in each preamble element.  Specific details are outside the scope of
   this document.


7.  Security Considerations

   Comparing to [I-D.ietf-avt-rapid-acquisition-for-rtp], this document
   specifies delivering PSI information to a RTP receiver prior to
   unicast RTP burst packets.  PSI is key information for a decoder to
   parse MPEG2-TS streaming packets, and any tampered PSI results in
   denial of service of the RTP receiver.  Security considerations in
   [I-D.ietf-avt-rapid-acquisition-for-rtp] also applies.


8.  Acknowledgements

   The authors thank the following individuals for their contributions,
   comments and suggestions to this document: Roni Even, Sandy
   (Alexander) MacInnis, VAN CAENEGEM Tom, Franceschini Guido, Eric



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   Friedrich, Ali C. Begen (abegen), Stephan Wenger, Colin Perkins,
   Ingemar Johansson S, Hui Deng, Martin Ellis, David R Oran.


9.  References

9.1.  Normative References

   [H.222.0]  ITU-T H.222.0(2000 E), "Information technology - Generic
              coding of moving pictures and associated audio information
              - Part 1: Systems".

   [H.222.0(2006)]
              ITU-T H.222.0(2006), "Information technology - Generic
              coding of moving pictures and associated audio information
              - Part 1: Systems", May 2006.

   [H.262]    ITU-T H.262(2000), "Information technology - Generic
              coding of moving pictures and associated audio information
              - Part 2: Video".

   [I-D.ietf-avt-rapid-acquisition-for-rtp]
              Steeg, B., Begen, A., Caenegem, T., and Z. Vax, "Unicast-
              Based Rapid Acquisition of Multicast RTP Sessions",
              draft-ietf-avt-rapid-acquisition-for-rtp-16 (work in
              progress), October 2010.

   [ISO13818-1]
              ISO/IEC 13818-1:2000(E), "Information technology - Generic
              coding of moving pictures and associated audio
              information: Systems".

   [ISO13818-11]
              ISO/IEC 13818-11:2004, "Information technology - Generic
              coding of moving pictures and associated audio information
              - Part 11: IPMP on MPEG-2 systems".

   [ISO13818-1:2007]
              ISO/IEC 13818-1:2007, "Information technology - Generic
              coding of moving pictures and associated audio
              information: Systems".

   [ISO13818-2]
              ISO/IEC 13818-2:2000, "Information technology - Generic
              coding of moving pictures and associated audio information
              - Part 2: Video".

   [ISO13818-3]



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              ISO/IEC 13818-3:1998, "Information technology - Generic
              coding of moving pictures and associated audio information
              - Part 3: Audio".

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC2250]  Hoffman, D., Fernando, G., Goyal, V., and M. Civanlar,
              "RTP Payload Format for MPEG1/MPEG2 Video", RFC 2250,
              January 1998.

   [RFC3388]  Camarillo, G., Eriksson, G., Holler, J., and H.
              Schulzrinne, "Grouping of Media Lines in the Session
              Description Protocol (SDP)", RFC 3388, December 2002.

   [RFC3550]  Schulzrinne, H., Casner, S., Frederick, R., and V.
              Jacobson, "RTP: A Transport Protocol for Real-Time
              Applications", STD 64, RFC 3550, July 2003.

   [RFC4566]  Handley, M., Jacobson, V., and C. Perkins, "SDP: Session
              Description Protocol", RFC 4566, July 2006.

   [RFC4585]  Ott, J., Wenger, S., Sato, N., Burmeister, C., and J. Rey,
              "Extended RTP Profile for Real-time Transport Control
              Protocol (RTCP)-Based Feedback (RTP/AVPF)", RFC 4585,
              July 2006.

   [RFC4588]  Rey, J., Leon, D., Miyazaki, A., Varsa, V., and R.
              Hakenberg, "RTP Retransmission Payload Format", RFC 4588,
              July 2006.

9.2.  Informational References

   [ATSC Doc. A/65]
              ATSC Document A/65, "ATSC Standard: Program and System
              Information Protocol(PSIP) for Terrestrial Broadcast and
              Cable".

   [ATSC Doc. A/69]
              ATSC Document A/69, "ATSC Recommended Practice: Program
              and System Information Protocol Implementation Guidelines
              for Broadcasters".

   [ETSI EN 300 468]
              ETSI EN 300 468, "Digital Video Broadcasting (DVB);
              Specification for Service Information (SI) in DVB
              systems".




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   [ETSI TS 101 197]
              ETSI TS 101 197, "Digital Video Broadcasting (DVB); DVB
              Simulcrypt - Head-end architecture and synchronization".

   [ETSI TS 103 197]
              ETSI TS 103 197, "Digital Video Broadcasting (DVB); Head-
              end implementation of DVB SimulCrypt".

   [I-D.ietf-avt-rtcp-guidelines]
              Ott, J. and C. Perkins, "Guidelines for Extending the RTP
              Control Protocol (RTCP)",
              draft-ietf-avt-rtcp-guidelines-04 (work in progress),
              May 2010.


Authors' Addresses

   Peilin Yang
   Huawei Technologies Co., Ltd.
   101 Software Avenue
   Nanjing 210012
   P.R.China

   Phone: +86 25 56622638
   Email: yangpeilin@huawei.com


   Frank Xia
   Huawei Technologies Co., Ltd.
   1700 Alma Dr. Suite 500
   Plano, TX 75075

   Phone: +1 972-509-5599
   Email: xiayangsong@huawei.com


   Xingfen Wu
   Huawei Technologies Co., Ltd.
   101 Software Avenue, Yuhua District
   Nanjing 210001
   P.R.China

   Phone: +86 25 84565870
   Email: wuxingfen@huawei.com







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