1、INTERNATIONAL STANDARD ISO/IEC 1381 8-6 First edition AMENDMENT 3 1998-09-01 2001 -08-1 5 Information technology - Generic coding of moving pictures and associated audio information - Part 6: Extensions for DSM-CC AMENDMENT 3: Transport buffer model in support of synchronized user-to-network downloa
2、d protocol Technologies de linformation - Codage gnrique des images animes et des informations sonores associes - Partie 6: Extensions pour DSM-CC AMENDEMENT 3: Modle de tampon de transport en support du protocole de chargement utilisateur-rseau synchronis Adopted by INCITS (InterNational Committee
3、for Information Technology Standards) as an American National Standard. Date of ANSI Approval: 4/5/02 Published by American National Standards Institute, 25 West 43rd Street, New York, New York 10036 Copyright 2002 by Information Technology Industry Council (ITI). All rights reserved. These material
4、s are subject to copyright claims of International Standardization Organization (ISO), International Electrotechnical Commission (IEC), American National Standards Institute (ANSI), and Information Technology Industry Council (ITI). Not for resale. No part of this publication may be reproduced in an
5、y form, including an electronic retrieval system, without the prior written permission of ITI. All requests pertaining to this standard should be submitted to ITI, 1250 Eye Street NW, Washington, DC 20005. Printed in the United States of America Reference number ISOIIEC 13818-6:1998/Amd.3:2001 (E) O
6、 ISOIIEC 2001 ISO/IEC 13818-6:1998/Amd.3:2001 (E) PDF disclaimer This PDF file may contain embedded typefaces. In accordance with Adobes licensing policy, this file may be printed or viewed but shall not be edited unless the typefaces which are embedded are licensed to and installed on the computer
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9、al Secretariat at the address given below. O ISO/IEC 2001 All rights reserved. Unless othetwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from either
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11、d.3:2001 (E) Foreword IS0 (the International Organization for Standardization) and IEC (the International Electrotechnical Commission) form the specialized system for worldwide standardization. National bodies that are members of IS0 or IEC participate in the development of International Standards t
12、hrough technical committees established by the respective organization to deal with particular fields of technical activity. IS0 and I EC technical committees collaborate in fields of mutual interest. Other international organizations, governmental and non-governmental, in liaison with IS0 and IEC,
13、also take part in the work. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 3. In the field of information technology, IS0 and IEC have established a joint technical committee, ISO/IEC JTC 1. Draft International Standards adopted by the joint te
14、chnical committee are circulated to national bodies for voting. Publication as an International Standard requires approval by at least 75 % of the national bodies casting a vote. Attention is drawn to the possibility that some of the elements of this Amendment may be the subject of patent rights. IS
15、0 and IEC shall not be held responsible for identifying any or all such patent rights. Amendment 3 to International Standard ISO/IEC 1381 8-6: 1998 was prepared by Joint Technical Committee ISO/IEC JTC 1, Information technology, Subcommittee SC 29, Coding of audio, picture, multimedia and hypermedia
16、 information. O ISOIIEC 2001 -All rights reserved iii ISO/IEC 13818-6:1998/Amd.3:2001 (E) Information technology - Generic coding of moving pictures and associated audio information - Part 6: Extensions for DSM-CC AMENDMENT 3: Transport buffer model in support of synchronized user-to-network downloa
17、d protocol Add the following new subclause. 9.2.9 T-STD buffer model for synchronized download protocol 9.2.9.1 Introduction The WEG-2 Transport System Target Decoder (T-STD) buffer model is defined for the Synchronized Download protocol. The buffer model includes a secondary multiplexing stage base
18、d on the tableid-extension field of the DSM- CC section structure. The secondary multiplexing stage allows multiple data modules of a single program element to be independently synchronized. A secondary channel is referenced as a data module channel. The tableid-extension field conveys a copy of the
19、 moduleId of the data module. Each data module channel is identified by the moduleId value shared by all data modules conveyed in this data module channel. The primary, conventional multiplexing stage uses the WEG-2 Transport Stream packets PID value to forward the packet payloads to their respectiv
20、e smoothing buffer. The payloads of the Transport Stream packets are all portions of DSM-CC sections of a program element of stream-type value 0x14. The DSM-CC sections convey Download Control messages or Download Data messages. Download control messages are conveyed in sections with tableid value O
21、x3B while Download Data messages are conveyed in sections with tableid value Ox3C. The section-number field identifies the block number of the data module conveyed in the section. The payloads of the DSM-CC section sharing the same tableid, tableid-extension and version-number field values are re-as
22、sembled in-order in the receiver to reconstruct the synchronized data modules. 9.2.9.2 Definitions Table 9-7 below defines the DSM-CC section payload as the bytes between the section header bytes and the CRC32 or checksum bytes at the end of the section. The concept of DSM-CC section payload is used
23、 in the definition of the T-STD for the Synchronized Download protocol. O ISOIIEC 2001 -All rights reserved 1 ISO/IEC 13818-6:1998/Amd.3:2001 (E) Table 9-7 DSM-CC Section Format Syntax No. of bits Mnemonic DSMCC-section() table-id 8 uimsbf section-syntax-indicator 1 bslbf complement-indicator 1 bslb
24、f reserved 2 bslbf section-length table-id-extension reserved version-number current-nextindicator section-number last-section-number DSM-CC section payload if(section-syntax-indicator = O) checksum 1 1 else CRC-32 12 uimsbf 16 uimsbf 2 bslbf 5 uimsbf 1 bslbf 8 uimsbf 8 uimsbf 32 uimsbf 32 rpchof DS
25、M-CC section header bytes shall correspond to the first 8 bytes of the DSM-CC section (from the tableid field to the last-section-number field included) and the last 4 bytes of the section (checksum or CRC-32 field). The section payload bytes are the bytes starting immediately following the last-sec
26、tion-number field and up to the field immediately preceding the checksum or CRC-32 field. A DSM-CC section payload includes a Download message header and a Download message. In the case of a Download Control message (tableid Ox3B), the message header is a dsmccMessageHeader structure. In the case of
27、 a Download Data message (tableid Ox3C), the message header is a dsmccDownloadDataHeader structure and the Download message is a DownloadDataBlock message. The payload of a DownloadDataBlock message shall be referenced as the Download data message payload. The payload of the DownloadDataBlock messag
28、e shall not include the moduleId, moduleVersion, reserved and blockNumber fields at the beginning of the message. The Download Data Message payload represents a portion of a synchronized data module. 9.2.9.3 Data module channels The secondary multiplexing/de-multiplexing stage operates on the tablei
29、d-extension fields of DSM-CC sections with tableid value Ox3C. DSM-CC sections conveying other messages (like the DownloadInfoIndication message) may be conveyed in the same program element. It is only in the case of tableid equal to Ox3C that the tableid-extension field values are used to identify
30、the data module channels. The Transport System Target Decoder buffer model for synchronized data elementary streams includes a Transport Buffer, a Smoothing Buffer and a Data Module Buffer. The purpose of the Data Module buffer is to allow for the re- assembly of the synchronized data modules before
31、 they are decoded and presented in the receiver. 9.2.9.4 Transport system target decoder buffer model Complete Transport Stream packets containing data from program element n of stream-type 0x14 are passed to the transport buffer for program element n, TBn. The size of TBn is fixed and equal to 5 12
32、 bytes. This includes duplicate Transport Stream packets and packets with no payloads. Transfer of any data from the System Target Decoder input to TBn is considered instantaneous. Ail data that enter TBn are removed from TBn at a rate RXn. When there are no data in TBn, the rate RXn is equal to O.
33、Bytes that are part of a DSM-CC section are delivered to the Smoothing buffer SBn. Other bytes are not and may be used to control the system. Duplicate Transport Stream packets are not delivered to SBn. Ail bytes enter SBn 2 O ISOIIEC 2001 -All rights reserved ISO/IEC 13818-6:1998/Amd.3:2001 (E) ins
34、tantaneously upon leaving the buffer TBn. Ail bytes that enter the smoothing buffer SBn leave the smoothing buffer SBn. The data module stream bytes in buffer SBn are all delivered to their associated data module buffer at the rate sbleak-n. The value of sbleak-n is either defined implicitly or list
35、ed explicitly in the ISOIEC 13818-1 smoothing-bufferdescriptor. The value of the leak rate may follow the classification specified in Table 7-13 of Section 7.5.5 of this specification. The size of SBn, SBSn, is implicitly declared or listed explicitly in the ISO/IEC 13818-1 smoothing-bufferdescripto
36、r. Only synchronized data module data bytes (bytes of a Download data message payload) in data module k of program element n enter the data module buffer DMBnk. If there is DSM-CC section data in SBn and buffer DMBnk is not full, the data is transferred from SBn to DMBnk at a rate defined by sbleak-
37、n. When there is no DSM-CC section data in SBn, no data is removed from SBn. Bytes from a DSM-CC section header are removed instantaneously and discarded and may be used to control the system. Bytes from a DSM-CC section CRC-32 field or checksum field that immediately follow the last data module byt
38、e in the DSM-CC section payload are removed instantaneously and discarded and may be used to verify the integrity of the data. Bytes from the dsmccDownloadDataHeader message header and the first 6 bytes of the DowdoadDataBlock message (representing the moduleId, moduleVersion, reserved and blockNumb
39、er fields of the message) are discarded and may be used to control the system. Bytes from the payload of a DSM-CC section with a tableid value other than Ox3C are taken out of buffer SBn at rate sbleak-n. These bytes are subsequently discarded and may be used to control the system. All bytes that en
40、ter the smoothing buffer SBn leave it. Ail data module bytes of data module stream n enter the data module de- multiplexer instantaneously upon leaving SBn. The size of the buffer DMBnk is DMBSnk. The value of DMBSnk shall be at least equal to the largest size that synchronized module k can take in
41、program element n. In buffer DMBnk, the synchronized data modules shall be reconstructed from the in-order concatenation of the DownloadDataBlock data message payloads as indicated by the section-number field of the DSM-CC section headers. The DSM-CC sections conveying a synchronized data module are
42、 identified by unique tableid, tableid-extension and version-number values. For the Data Elementary Buffer DMBnk, all data for the data module that has been in the buffer longest are removed instantaneously at time td-nk. The Decoding time td-nk may be specified by the Presentation Time Stamp locate
43、d in the adaptation field of the dsmccDowdoadDataMessageHeader in the first section (section-number 0x00) conveying the synchronized data module and a Data Module Decode Time (DMDT) common to all data modules in the program element n. The value of DMDT may be signaled in the MPEG-2 Transport Stream
44、(e.g., in the moduleInfoBytes in the DowloadInfoIndication message). Alternatively, the value of td-nk may be equal to the PTS of the previous data module in the data module channel when the value of DMDT is not specified. The presentation data unit resulting from decoding the data module is present
45、ed at the instant specified by the PTS field associated with the synchronized data module. Buffer TBn shall not overflow. Buffer SBn shall not overflow. Buffer DMBnk shall not overflow nor underflow. Underflow of DMBnk occurs when one or more bits of the data module is not present in DMBnk at the Da
46、ta Module Decode Time associated with the data module. In the example shown in Figure 9-1 below, three synchronized or synchronous data elementary streams, nk, nj and nh, multiplexed within the same program element referenced by PID value OxOFDA. To the right of the smoothing buffer SBn, a secondary
47、 de-multiplexing operates on the tableid-extension field to route the data module bytes to their respective data module channels. A collection of synchronized data streams is conveyed in MPEG sections where tableid is equal to Ox3C and tableid-extension is equal to OxABCD, 0x9876 and 0x1 122. Each v
48、alue of the tableid-extension field identifies the secondary channel on which a data elementary sub-stream is being conveyed. Figure 9-1 also shows three synchronized or synchronous data elementary streams mk, mj and mh multiplexed in the MPEG-2 program element referenced by PID value 0x1753 and in
49、MPEG sections with tableid field value equal to ox3c. The following notation is used in Figure 9-1 : TBn is the transport buffer. SBn DMBk Rx, sbleak, And0 tdnko) is the smoothing buffer for program element n. is the data module buffer for data module channel k of program element n. is the rate at which data is removed from TB,. is the rate at which data is removed from SB,. is the j* access unit for data module channel k of program element n. is the decoding time in the system target decoder of the jth access unit in data module channel k of program element n. O ISOIIEC
