1、 INTERNATIONAL TELECOMMUNICATION UNION ITU-T J.124TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (03/2004) SERIES J: CABLE NETWORKS AND TRANSMISSION OF TELEVISION, SOUND PROGRAMME AND OTHER MULTIMEDIA SIGNALS Interactive systems for digital television distribution Multiplexing format for multimedia
2、 webcasting over TCP/IP networks ITU-T Recommendation J.124 ITU-T Rec. J.124 (03/2004) i ITU-T Recommendation J.124 Multiplexing format for multimedia webcasting over TCP/IP networks Summary This Recommendation provides an extended multiplexing format based on ITU-T Rec. J.123, which is appropriate
3、for audio and video transmission by download-based protocol over TCP/IP without any session control protocols between server and client, a.k.a. “Progressive Download“. Fragmented structure is newly introduced into this Recommendation. In the fragment structure, media data is divided into media fragm
4、ents, and a movie header is also divided into movie fragment headers according to the fragmented media data. Each movie fragment header corresponds to each media fragment, and these elements constitute a movie fragment. By adapting the fragment structure to long duration content, a huge header, whic
5、h causes initial delay of the progressive streaming, can be avoided. In addition, formatted text information is stored in the media data so that these can be interleaved with one another in a file. This format also carries metadata, digital rights management (DRM) information as well as audio, video
6、 and text bitstreams. Examples of use of this Recommendation are given in Appendices I, II and III. Source ITU-T Recommendation J.124 was approved on 15 March 2004 by ITU-T Study Group 9 (2001-2004) under the ITU-T Recommendation A.8 procedure. ii ITU-T Rec. J.124 (03/2004) FOREWORD The Internationa
7、l Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications. The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations o
8、n them with a view to standardizing telecommunications on a worldwide basis. The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics. The approval of
9、ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1. In some areas of information technology which fall within ITU-Ts purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. NOTE In this Recommendation, the expression “Administration“ is
10、used for conciseness to indicate both a telecommunication administration and a recognized operating agency. Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure e.g. interoperability or applicability) and compliance with th
11、e Recommendation is achieved when all of these mandatory provisions are met. The words “shall“ or some other obligatory language such as “must“ and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of
12、 any party. INTELLECTUAL PROPERTY RIGHTS ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Pr
13、operty Rights, whether asserted by ITU members or others outside of the Recommendation development process. As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However,
14、implementors are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database. ITU 2004 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. ITU-T
15、Rec. J.124 (03/2004) iii CONTENTS Page 1 Scope 1 2 References. 1 2.1 Normative references 1 2.2 Informative references 1 2.3 Bibliography. 1 3 Terms and definitions . 2 4 Abbreviations 2 5 Reference architecture 2 6 Multiplexing format 3 6.1 Basic structure 3 6.2 Object structure 3 6.3 Box order 5 6
16、.4 Track structure 6 6.5 Media data structure . 6 6.6 Other descriptions. 6 7 Box definitions . 6 7.1 File type box. 6 7.2 Other boxes. 7 8 Digital Rights Management (DRM) box 7 8.1 Syntax. 8 8.2 Semantics 8 9 Timed text format . 8 9.1 Unicode support 8 9.2 Bytes, characters, and glyphs . 9 9.3 Char
17、acter set support 9 9.4 Font support 9 9.5 Fonts and metrics 10 9.6 Colour support 10 9.7 Text rendering position and composition. 10 9.8 Marquee scrolling. 12 9.9 Language 13 9.10 Writing direction 13 9.11 Text wrap 14 9.12 Highlighting, Closed Caption, and Karaoke. 14 9.13 Media handler. 14 9.14 M
18、edia handler header . 14 9.15 Style record. 14 9.16 Sample description format 15 iv ITU-T Rec. J.124 (03/2004) Page 9.17 Sample format 16 9.18 Combinations of features 20 Appendix I Application example: Typical VOD transmission. 21 Appendix II Application example: Random access transmission. 22 Appe
19、ndix III Application example: Live video transmission. 23 ITU-T Rec. J.124 (03/2004) 1 ITU-T Recommendation J.124 Multiplexing format for multimedia webcasting over TCP/IP networks 1 Scope This Recommendation defines a multiplexing format appropriate for progressive download, audio and video transmi
20、ssion by download-based protocol over TCP/IP. In contrast to ITU-T Rec. J.123, this Recommendation supports fragmented structure for long duration content. In addition, formatted text information is stored in the media data so that these can be interleaved with one another in a file. Using this form
21、at, webcasting of long duration content and live programs is realized. 2 References The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were
22、 valid. All Recommendations and other references are subject to revision; 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 valid ITU-T Recommendat
23、ions is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation. 2.1 Normative references 1 ITU-T Recommendation J.123 (2002), Multiplexing format for webcasting on TCP/IP network. 2 ISO/IEC 14496-12:2004
24、, Information technology Coding of audio-visual objects Part 12: ISO base media file format. 3 ISO/IEC 14496-14:2003, Information technology Coding of audio-visual objects Part 14: MP4 file format. 2.2 Informative references 4 ITU-T Recommendation J.120 (2000), Distribution of sound and television p
25、rograms over the IP network. 5 ISO/IEC 14496-2:2001, Information technology Coding of audio-visual objects Part 2: Visual. 6 ISO/IEC 14496-3:2001, Information technology Coding of audio-visual objects Part 3: Audio. 7 IETF RFC 2068 (1997), Hypertext Transfer Protocol HTTP/1.1. 2.3 Bibliography 8 3GP
26、P TS 26.245:2003, Transparent end-to-end streaming service; Timed text format. 2 ITU-T Rec. J.124 (03/2004) 3 Terms and definitions This Recommendation defines the following terms: 3.1 box: An object-oriented building block defined by a unique type identifier and length 2. 3.2 chunk: A contiguous se
27、t of samples for one track. 3.3 container box: A box whose sole purpose is to contain and group a set of related boxes. 3.4 movie box: A container box whose sub-boxes define the metadata for a presentation (moov). 3.5 media data box: A container box which can hold the actual media data for a present
28、ation (mdat). 3.6 presentation: One or more motion sequences, possibly combined with audio. 3.7 progressive download: Streaming by download-based protocol over TCP/IP without any session control protocols. Client can start playing the media before the full file is downloaded. 3.8 sample: An individu
29、al frame of video, or a time-contiguous compressed section of audio. 3.9 sample description: A structure which defines and describes the format of some number of samples in a track. 3.10 sample table: A packed directory for the timing and physical layout of the samples in a track. 3.11 track: A coll
30、ection of related samples, which corresponds to a sequence of images or sampled audio. 3.12 webcasting: Webcasting is defined in ITU-T Rec. J.120, “Distribution of sound and television programs over the IP network“. 4 Abbreviations This Recommendation uses the following abbreviations: DRM Digital Ri
31、ghts Management HTTP HyperText Transport Protocol IP Internet Protocol MP4 MPEG-4 File Format SMIL Synchronized Multimedia Integration Language TCP Transmission Control Protocol UTF-8 Unicode Transformation Format (the 8-bit form) UTF-16 Unicode Transformation Format (the 16-bit form) UUID Universal
32、 Unique Identifier 5 Reference architecture This Recommendation assumes that download-based protocol (e.g., HTTP) should be used for multimedia webcasting because it does not require any complex server-client protocols. The reference architecture for multimedia webcasting on TCP/IP is shown in Figur
33、e 5-1. ITU-T Rec. J.124 (03/2004) 3 Figure 5-1/J.124 Architecture of multimedia webcasting on TCP/IP networks 6 Multiplexing format 6.1 Basic structure The format is structurally based on the ISO base media file format defined in 2. Basic structure of the format is shown in Figure 6-1, which consist
34、s of extension data, contents header and media data. Figure 6-1/J.124 Basic structure of a file format 6.2 Object structure The file is structured as a sequence of objects called “Box“; some of these objects may contain other objects. The sequence of objects in the file shall contain exactly one pre
35、sentation metadata wrapper 4 ITU-T Rec. J.124 (03/2004) (the movie box moov). It should be close to the beginning of the file. The other objects found at this level may be file type box ftyp, uuid box, movie fragments moof, and media data boxes mdat. All boxes defined in this Recommendation are list
36、ed in Table 6-1, and are indicated by grey shading. Table 6-1/J.124 Box types and structure ftyp file type and compatibility uuid uuid box for DRM (see clause 8) moov container for all the information mvhd movie header, overall declarations trak container for an individual track or stream tkhd track
37、 header, overall information about the track tref track reference container edts edit list container elst an edit list mdia container for the media information in a track mdhd media header, overall information about the media hdlr handler, declares the media (handler) type minf media information con
38、tainer vmhd video media header, overall information smhd sound media header, overall information hmhd hint media header, overall information nmhd null media header, overall information dinf data information box, container dref data reference box, declares source(s) of media data in track stbl sample
39、 table box, container for the time/space map stsd sample descriptions (codec types, initialization etc.) stts (decoding) time-to-sample ctts (composition) time to sample stsc sample-to-chunk, partial data-offset information stsz sample sizes (framing) stz2 compact sample sizes (framing) stco chunk o
40、ffset, partial data-offset information co64 64-bit chunk offset stss sync sample table (random access points) stsh shadow sync sample table padb sample padding bits stdp sample degradation priority mvex movie extends box mehd movie extends header box trex track extends defaults ITU-T Rec. J.124 (03/
41、2004) 5 Table 6-1/J.124 Box types and structure moof movie fragment mfhd movie fragment header traf track fragment tfhd track fragment header trun track fragment run mfra movie fragment random access (optional) tfra track fragment random access mfro movie fragment random access offset mdat media dat
42、a container free free space skip free space udta user-data cprt copyright, etc. 6.3 Box order This Recommendation defines box order as follows. Only the top-level boxes are indicated. 6.3.1 Non-fragmented structure As shown in Figure 6-2, the boxes are transmitted or stored from left to right order.
43、 Exactly one file type box (ftyp), exactly one DRM UUID box (uuid), exactly one movie box (moov) and exactly one media data box (mdat) shall exist in the format. Other boxes not defined in this Recommendation may occur and decoders shall skip and ignore any unrecognized box. ftyp DRM(uuid) moov mdat
44、 Figure 6-2/J.124 Non-fragmented structure 6.3.2 Fragmented structure Fragmented structure should be used for long duration content. The first fragment is the same as that of non-fragmented structure as shown in Figure 6-3. ftyp DRM(uuid) moov mdat Figure 6-3/J.124 The first fragment For the second
45、and subsequent fragments, each fragment shall consist of exactly one movie fragment box (moof) and exactly one media data box (mdat). The fragments shall be in sequence order as shown in Figure 6-4. moof mdat moof mdat Figure 6-4/J.124 The second fragment and subsequent fragments 6 ITU-T Rec. J.124
46、(03/2004) 6.4 Track structure This Recommendation defines the following track structure. One video track; One audio track; One video track and one audio track; One video track and one text track; One audio track and one text track; One video track, one audio track and one text track. The maximum num
47、ber of tracks shall be one for video, one for audio and one for text. Moreover, at least one video or one audio track shall exist. The maximum number of sample entries shall be one per track for video and audio, but unrestricted for text. 6.5 Media data structure If the media data contains multiple
48、tracks, it shall be interleaved inside the format as chunks. The interleaving order shall correspond to the track storing order. Chunks corresponding to the track shall be in time order. One second interleaving length is recommended, and it shall be less than five seconds. 6.6 Other descriptions Thi
49、s Recommendation applies the following descriptions to ISO base media file format 2. The fields in the objects are stored with the most significant byte first, commonly known as network byte order or big-endian format. There shall be no references to external media outside the format, i.e., a data shall be self-contained. Hint tracks are a mechanism that a server implementation may choose to use in preparation for the streaming of media content. However, it should be noted that the
