1、INTERNATIONAL TELECOMMUNICATION UNION ITU-T TELECOMMUNICATION STAN DARD IZATION SECTOR OF ITU H.222.1 (03/9 6) TRANSMISSION OF NONITELEPHONE SIGNALS MULTIMEDIA MULTIPLEX AND SYNCHRONIZATION FOR AUDIOVISUAL COMMUNICATION IN ATM ENVIRONMENTS ITU-T Recommendation H.222.1 (Previously “CCITT Recommendati
2、on”) FOREWORD The IT-T (Telecommunication Standardization Sector) is a permanent organ of the International Telecommunication Union (). The ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommen- dations on them with a view to standardizing telecommunication
3、s on a worldwide basis. The World Telecommunication Standardization Conference (WTSC), which meets every four years, establishes the topics for study by the ITU-T Study Groups which, in their turn, produce Recommendations on these topics. The approval of Recommendations by the Members of the -T is c
4、overed by the procedure laid down in WTSC Resolution No. 1 (Helsinki, March 1-12, 1993). IT-T Recommendation H.222.1 was prepared by IT-T Study Group 15 (1993-1996) and was approved under the WTSC Resolution No. 1 procedure on the 19th of March 1996. NOTE In this Recommendation, the expression “Admi
5、nistration” is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. O IT 1996 All rights reserved. No part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microf
6、ilm, without permission in writing from the ITU. STD-ITU-T RECMN H*222*L-ENGL 177b 48b2591 Ob21170 335 8 9 10 11 12 13 14 15 16 17 18 19 20 CONTENTS Scope References Terms and definitions . 4 Abbreviations General . Sewices provided by Recommendation H.222.1 . H.222.1 Program Stream 7.1 7.2 H.222.1
7、Program Stream timing model H.222.1 Transport Stream 8.1 8.2 H.222.1 Network adaptation functions Interaction with the AAL . 10.1 AAL type 1 . 10.2 AAL type 5 . 11.1 In-band subchannel signalling 11.2 Out-of-band subchannel signalling . 11.3 Default subchannels H.222.1 stream-id Use of multiple ATM
8、Virtual Channel Connections 13.1 General 13.2 H.222.1 Program Stream syntax and semantics H.222.1 Transport Stream syntax and semantics H.222.1 Transport Stream timing model Subchannel signalling Hierarchical coded video and multiple ATM Virtual Channel Connections Descriptors . IT-T Recommendation
9、H.222.0 descriptor priority . 14.2 IT-T H.222.1 descriptors . Synchronization of H.222.1 defined elementary stream types . 15.1 H.261 video 15.2 H.263 video 15.3 G.711 audio 15.4 G.722 audio 15.5 G.723 audio 15.6 G.728 audio System Target Decoder for H.222.1 defined elementary stream types 16.1 Prog
10、ram Streams . Video frame synchronous signalling Mode changing . 14.1 16.2 Transport Streams . Encryption H.222.1 demultiplexer errors . Appendix I . Recommended usage of H.222.0 descriptors Appendix II . IT-T Timing Descriptor usage . Page 1 1 2 2 2 3 5 5 5 5 5 5 5 5 5 6 7 7 7 8 8 9 9 10 10 10 11 1
11、6 16 17 17 17 17 17 17 17 18 18 18 18 18 19 20 Recommendation H.222.1 (03/96) 1 STD-ITU-T RECMN H-222.1-ENGL 197b LiBb2571 Ob21171 271 SUMMARY This Recommendation describes the multiplexing and synchronization of multimedia information for audiovisual communications in ATM environments. It specifies
12、 the H.222.1 Program Stream and the H.222.1 Transport Stream by choosing necessary coding elements from the generic H.222.0 specifications and by adding items for use in ATM environments. It also covers methods for accommodating ITU-T defined elementary streams. 11 Recommendation H.222.1 (03196) Rec
13、ommendation H.222.1 MULTIMEDIA MULTIPLEX AND SYNCHRONIZATION FOR AUDIOVISUAL COMMUNICATION IN ATM ENVIRONMENTS (Geneva, I996) 1 Scope This Recommendation describes the multiplexing and synchronization of multimedia information, for audiovisual communication in ATM environments. This Recommendation s
14、pecifies the peer-to-peer syntax, semantics and procedures, and the interactions with the AAL. 2 References The following Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editi
15、ons indicated were valid. All Recommendations and other references are subject to revision; all users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently v
16、alid -T Recommendations is regularly published. CCITT Recommendation G.711 (1988), Pulse Code Modulation (PCM) of voice frequencies. CCIT Recommendation G.722 (1988), 7 kHz audio-coding within 64 kbius. ITU-T Recommendation G.723.1 (1 996), Dual rate speech coder for multimedia communication transmi
17、tting at 5.3 and 6.3 kbius. CCITT Recommendation G.728 (1992), Coding of speech at 16 kbius using low-delay code excited linear prediction. ITU-T Recommendation H.222.0 (1995) I ISO/IEC 13818-1:( 1996), Information technology - Generic coding of moving pictures and associated audio information: Syst
18、ems. ITU-T Recommendation H.233 (1995), Confidentialis, system for audiovisual services. ITU-T Recommendation H.245 (1996), Control protocol for multimedia communication. ITU-T Recommendation H.261 (1993), Video codee for audiovisual services atp x 64 kbit/s. ITU-T Recommendation H.262 (1995) I ISO/
19、IEC 13818-2:(1995), Information technology - Generic coding of moving pictures and associated audio information: Video. ITU-T Recommendation H.263 (1996), Video coding for low bit rate communication. ITU-T Recommendation 1.3 1 1 (1993), B-ISDN general network aspects. ITU-T Recommendation 1.361 (199
20、5), B-ISDN ATM layer specification. ITU-T Recommendation 1.362 (1993), B-ISDN ATM Adaptation iuyer (AAL)functional description. ITU-T Recommendation 1.363 (1993), B-ISDNATM Adaptation iuyer (AAL) specjication. ITU-T Recommendation T. 120 (1996), Dura protocols for multimedia conferencing. ITU-T Reco
21、mmendation Q.293 1 (1993, Broadband Integrated Services Digital Network (B-ISDN) - Digital Subscriber Signalling System No. 2 (DSS 2) - User-Network Inreflace (UNI) layer 3 specification for basic call connection control. Recommendation H.222.1 (03/96) 1 - STD-ITU-T RECMN H-222-1-ENGL 177b m 4b2571
22、Ob21173 O44 = 3 Terms and definitions For the purposes of this Recommendation, the following definition applies: 3.1 subchannel: A logical channel in Recommendation H.222.1 formed from packets having a unique multiplex identifier field value. A subchannel carries one H.222.1 elementary stream. A sub
23、channel is unidirectional. There may be many subchannels within one ATM Virtual Channel. 4 Abbreviations For the purposes of this Recommendation the following abbreviations are used: AAL ATM Adaptation Layer ACELP ATM Asynchronous Transfer Mode CA Conditional Access CDV Cell Delay Variation CPCS Com
24、mon Part Convergence Sublayer DP Data Partitioning DTS Decoding Time Stamp EOB End-of-B lock GOP Group of Picture LD-CELP MBA Macro Block Address MP-MLQ Multi-Pulse Maximum Likelihood Quantization PCR Program Clock Reference PDU Protocol Data Unit PES Packetized Elementary Stream PS Program Stream P
25、SI Program Specific Information PSM Program Stream Map PTS Presentation Time Stamp QOS Quality of Service RTI Real Time interface SCR System Clock Reference SDU Service Data Unit STC System Time Clock STD System Target Decoder TS Transport Stream Algebraic Codebook Excited Linear Prediction Low-Dela
26、y Codebook Excited Linear Prediction 5 General This Recommendation deals with the multiplexing and synchronization of multiple multimedia signals, for use in audiovisual communications in ATM environments. The multimedia signals may be coded audio or video or other data signals. This Recommendation
27、is suitable for various applications such as conversational services, distributive services, retrieval services and messaging services. 2 Recommendation H.222.1 (03196) This Recommendation is applicable to both unidirectional and bidirectional physical connections. A bi-directional connection may be
28、 symmetrical or asymmetrical. This Recommendation addresses constant bit rate coded video. No specific support is provided for variable bit rate coded video. Variable bit rate coded video is however not precluded. This Recommendation uses the services provided by the AAL. The AAL is specified in Rec
29、ommendation 1.363 14. The use of AAL type 1 and type 5 is specified here. This Recommendation may also be suitable for use in environments other than ATM. This Recommendation specifies two separate and independent protocols. They are: 0 H.222.1 Program Stream. 0 H.222.1 Transport Stream. These two p
30、rotocols are based upon the Program Stream and Transport Stream respectively, defined in Recommendation H.222.0 5. This Recommendation specifies the necessary coding elements in H.222.0 plus additional functionalities to form the H.222.1 Program Stream protocol and the H.222.1 Transport Stream proto
31、col. An overview of H.222.1 and its relation to Recommendation H.222.0 is shown in Figure 1. I H.222.1 H.222.0 Program Stream H.222.0 Transport Stream + H.222.1 Network adaptation I T151 30-9Ydl 1 FIGURE 1M.222.1 H.222.1 overview 6 Services provided by Recommendation H.222.1 The following services a
32、re provided by H.222.1 to the H.222.1 user: a) Multiplexing Multiplexing is based on a sequence of PDUs, each of which carry consecutive data from one and only one media source type, i.e. audio, video or other data signals. In the H.222.1 Program Stream these PDUs may be of variable length and relat
33、ively large in size. In the H.222.1 Transport Stream these PDUs are of fixed length and of relatively small size. The H.222.1 Transport Stream has a large multiplex capacity. Recommendation H.222.1 (03/96) 3 STD-ITU-T RECMN H-222-L-ENGL 177b M i8b2571 Ob21175 917 b) Timebase recovery A program is a
34、collection of associated media, all of which refer to a common timebase. The timebase is referred to as the System Time Clock (STC). The H.222.1 Program Stream supports one and only one program. The H.222.0 Transport Stream supports multiple programs. H.222.1, however, constrains the number of progr
35、ams in the Transport Stream to be one. The send side and receive side each have their own timebases. Time stamps attached to specific PDUs identify the intended time of arrival of the PDU at the receive side. Synchronization of the receive side timebase with the send side timebase may be achieved us
36、ing these time stamps. H.222.1 provides optional additional timebase recovery information, which may be useful in jittered environments. c) Media presentation synchronization Additional time stamps identify times at which entities in each media are to be presented to the end user. d) Timing jitter r
37、emoval Recommendation H.222.1 may offer the capabilities to remove the effects of time delay variation on the encoded bit stream at the receiver. e) Buffer management Rules are specified so as to avoid underflow and overflow of receive side buffers. This is achieved by a hypothetical receive side ti
38、ming model, which specifies timing relationships between outgoing PDUs at the send side. f) Security and access control Security and access control services are provided by media encryption. Support for entitlement control and management messages is also provided. g) In-band signalling The multiplex
39、ing service provides multiple connection end points at the userkI.222.1 service boundary. Protocol is provided that signais to the receive side the association between a PDU and a connection end point. The nature of the information carried by the connection is also described. h) Error reporting Prot
40、ocol at the receive side reports error conditions to the H.222.1 user. i) Trick mode Mechanisms to support video recorder like control functionality, e.g. fast forward, rewind etc. are included. j) Network maintenance A network maintenance service, which monitors channel errors, is available. k) Rem
41、ultiplex support In the H.222.1 Transport Stream mechanisms to assist in the addition and removal of individual elementary streams are provided. This service only has meaning at a network element. This service is not explicitly supported in the H.222.1 Program Stream. 1) Local program insertion In t
42、he H.222.1 Transport Stream mechanisms are provided to assist in the replacement of one elementary stream with another elementary stream. This service only has meaning at a network element. This service is not explicitly supported in the H.222.1 Program Stream. m) Priority In the H.222.1 Transport S
43、tream, one of two priorities may be indicated for each PDU. This service only has meaning at a network element. This service is not explicitly supported in the H.222.1 Program Stream. it is not stated here as to which services are mandatory. An application decides what services are appropriate. 4 Re
44、commendation H.222.1 (03/96) STD-ITU-T RECMN H*222*L-ENGL L77b i8b257L Ob2LL7b 853 7 H.222.1 Program Stream 7.1 The H.222.0 Program Stream syntax and semantics apply, as defined in 2.5.3H.222.0. The H.222.0 Program Stream Map is defined in 2.5.4M.222.0. See clause 11 for details of H.222.1 usage of
45、the H.222.0 PSM. H.222.1 Program Stream syntax and semantics The H.222.0 Program Stream Directory is defined in 2.5.5/H.222.0. Use of the H.222.0 Program Stream Directory is optional in the H.222.1 Program Stream. 7.2 H.222.1 Program Stream timing model The H.222.0 Program Stream System Target Decod
46、er as defined in 2.5.2M.222.0 applies. 8 H.222.1 Transport Stream The H.222.0 Transport Stream supports multiple programs, where a program is as defined in Recommendation H.222.0. Recommendation H.222.1 supports only single program Transport Streams. Multiple program Transport Streams are not suppor
47、ted. 8.1 H.222.1 Transport Stream syntax and semantics The H.222.0 Transport Stream syntax and semantics apply, as defined in 2.4.3M.222.0. The H.222.0 Program Specific Information (PSI) is defined in 2.4.4M.222.0. See clause 1 1 for details of H.222.1 usage of the H.222.0 PSI. 8.2 The Transport Str
48、eam System Target Decoder as defined in 2.4.2M.222.0 applies. H.222.1 Transport Stream timing model 9 H.222.1 Network adaptation functions Recommendation H.222.1 may offer the capabilities to remove the effects of time-delay variation on the encoded bit stream at the receiver. No specific syntax is
49、provided. The actual mechanism used is application dependent. NOTE - The Cell Delay Variation (CDV) at the input of the H.222.1 decoder depends on the network size, the volume and the characteristics of accommodated traffic, amongst other factors. It is assumed that the CDV value may be of the order of about 1-3 ms for CBR traffic at 156 Mbit/s data rate. If the H.222.0 decoder implementation can only accept CDV less than the above value at its input, then the H.222.1 network adaptation should provide the necessary CDV reduction. Allocation of the allo
