ANSI INCITS ISO IEC 14496-14-2003 Information technology - Coding of audio-visual objects - Part 14 MP4 file format《信息技术.音频-可视对象的编码.第14部分 MP4文件格式》.pdf

1、Adopted by INCITS (InterNational Committee for Information Technology Standards) as an American National Standard.Date of ANSI Approval: 5/10/2004Published by American National Standards Institute,25 West 43rd Street, New York, New York 10036Copyright 2004 by Information Technology Industry Council

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4、IEC 14496-14:2003(E)ISO/IEC 2003INTERNATIONAL STANDARD ISO/IEC14496-14First edition2003-11-15Information technology Coding of audio-visual objects Part 14: MP4 file format Technologies de linformation Codage des objets audiovisuels Partie 14: Format de fichier MP4 Copyright American National Standar

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10、ightiso.org Web www.iso.org Published in Switzerland ii ISO/IEC 2003 All rights reservedCopyright American National Standards Institute Provided by IHS under license with ANSI Not for ResaleNo reproduction or networking permitted without license from IHS-,-,-ISO/IEC 14496-14:2003(E) ISO/IEC 2003 All

11、 rights reserved iiiContents Page Foreword iv Introduction v 0.1 Derivation. v 0.2 Interchange v 0.3 Content Creation . v 0.4 Streamed presentation vi 1 Scope 1 2 Normative references . 1 3 Storage of MPEG-4 1 3.1 Elementary Stream Tracks. 1 3.2 Track Identifiers 3 3.3 Synchronization of streams. 4

12、3.4 Composition 5 3.5 Handling of FlexMux. 5 4 File Identification. 6 5 Additions to the Base Media Format. 6 5.1 Object Descriptor Box 7 5.2 Track Reference Types. 7 5.3 Track Header Box 8 5.4 Handler Reference Types. 8 5.5 MPEG-4 Media Header Boxes 8 5.6 Sample Description Boxes. 8 5.7 Degradation

13、 Priority Values. 10 6 Template fields used. 10 Annex A (informative) Patent statements 11 Copyright American National Standards Institute Provided by IHS under license with ANSI Not for ResaleNo reproduction or networking permitted without license from IHS-,-,-ISO/IEC 14496-14:2003(E) iv ISO/IEC 20

14、03 All rights reservedForeword ISO (the International Organization for Standardization) and IEC (the International Electrotechnical Commission) form the specialized system for worldwide standardization. National bodies that are members of ISO or IEC participate in the development of International St

15、andards through technical committees established by the respective organization to deal with particular fields of technical activity. ISO and IEC technical committees collaborate in fields of mutual interest. Other international organizations, governmental and non-governmental, in liaison with ISO a

16、nd IEC, also take part in the work. In the field of information technology, ISO and IEC have established a joint technical committee, ISO/IEC JTC 1. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2. The main task of the joint technical committe

17、e is to prepare International Standards. Draft International Standards adopted by the joint technical 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. ISO/IEC 14496-14 was prepar

18、ed by Joint Technical Committee ISO/IEC JTC 1, Information technology, Subcommittee SC 29, Coding of audio, picture, multimedia and hypermedia information. ISO/IEC 14496 consists of the following parts, under the general title Information technology Coding of audio-visual objects: Part 1: Systems Pa

19、rt 2: Visual Part 3: Audio Part 4: Conformance testing Part 5: Reference software Part 6: Delivery Multimedia Integration Framework (DMIF) Part 7: Optimized reference software for coding of audio-visual objects Part 8: Carriage of ISO/IEC 14496 contents over IP networks Part 9: Reference hardware de

20、scription Part 10: Advanced Video Coding (AVC) Part 11: Scene description and application engine Part 12: ISO base media file format Part 13: Intellectual Property Management and Protection (IPMP) extensions Part 14: MP4 file format Part 15: Advanced Video Coding (AVC) file format Part 16: Animation

21、 Framework eXtension (AFX) Copyright American National Standards Institute Provided by IHS under license with ANSI Not for ResaleNo reproduction or networking permitted without license from IHS-,-,-ISO/IEC 14496-14:2003(E) ISO/IEC 2003 All rights reserved vIntroduction 0.1 Derivation This specificat

22、ion defines MP4 as an instance of the ISO Media File format ISO/IEC 14496-12 and ISO/IEC 15444-12. The general nature of the ISO Media File format is fully exercised by MP4. MPEG-4 presentations can be highly dynamic, and there is an infrastructure the Object Descriptor Framework , which serves to m

23、anage the objects and streams in a presentation. An Initial Object Descriptor serves as the starting point for this framework. In the usage modes documented in the ISO Media File, an Initial Object Descriptor would normally be present, as shown in the following diagrams. 0.2 Interchange The followin

24、g diagram gives an example of a simple interchange file, containing two streams. IODmoovmp4 filemdattrak (BIFS)trak (OD)trak (video)trak (audio)other boxesInterleaved, time-ordered, BIFS, OD, video, and audio access unitsFigure 1 Simple interchange file 0.3 Content Creation In the following diagram,

25、 a set of files being used in the process of content creation is shown. Copyright American National Standards Institute Provided by IHS under license with ANSI Not for ResaleNo reproduction or networking permitted without license from IHS-,-,-ISO/IEC 14496-14:2003(E) vi ISO/IEC 2003 All rights reser

26、vedwith other unused data media file mp4 file BIFS access units possibly unordered with other unused data Video and audio access units possibly unordered mdat IOD moov mp4 file trak (BIFS) trak (OD) trak (video) trak (audio) other boxes other boxes (inc. moov) Figure 2 Content Creation File 0.4 Stre

27、amed presentation The following diagram shows a presentation prepared for streaming over a multiplexing protocol, only one hint track is required. IOD moov mp4 file mdat trak (BIFS) trak (OD) trak (video) trak (audio) other boxes Interleaved, time-ordered, BIFS, OD, video, and audio access units, an

28、d hint instructions hint Figure 3 Hinted Presentation for Streaming Copyright American National Standards Institute Provided by IHS under license with ANSI Not for ResaleNo reproduction or networking permitted without license from IHS-,-,-INTERNATIONAL STANDARD ISO/IEC 14496-14:2003(E) ISO/IEC 2003

29、All rights reserved 1Information technology Coding of audio-visual objects Part 14: MP4 file format 1 Scope This International Standard defines the MP4 file format, as derived from the ISO Base Media File format. 2 Normative references The following referenced documents are indispensable for the app

30、lication of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO/IEC 14496-1:2001, Information technology Coding of audio-visual objects Part 1: Systems ISO/IEC 14496-12: Inf

31、ormation technology Coding of audio-visual objects Part 12: ISO base media file format (technically identical to ISO/IEC 15444-12) 3 Storage of MPEG-4 3.1 Elementary Stream Tracks 3.1.1 Elementary Stream Data To maintain the goals of streaming protocol independence, the media data is stored in its m

32、ost natural format, and not fragmented. This enables easy local manipulation of the media data. Therefore media-data is stored as access units, a range of contiguous bytes for each access unit (a single access unit is the definition of a sample for an MPEG-4 media stream). This greatly facilitates t

33、he fragmentation process used in hint tracks. The file format can describe and use media data stored in other files, however this restriction still applies. Therefore if a file is to be used which contains pre-fragmented media data (e.g. a FlexMux stream on disc), the media data will need to be copi

34、ed to re-form the access units, in order to import the data into this file format. This is true for all stream types in this specification, including such meta-information streams as Object Descriptor and the Clock Reference. The consequences of this are, on the positive side, that the file format t

35、reats all streams equally; on the negative side, this means that there are internal cross-links between the streams. This means that adding and removing streams from a presentation will involve more than adding or deleting the track and its associated media-data. Not only must the stream be placed i

36、n, or removed from, the scene, but also the object descriptor stream may need updating. For each track, the entire ES-descriptor is stored as the sample description or descriptions. The SLConfigDescriptor for the media track shall be stored in the file using a default value (predefined = 2), except

37、when the Elementary Stream Descriptor refers to a stream through a URL, i.e. the referred stream is outside the scope of the MP4 file. In that case the SLConfigDescriptor is not constrained to this predefined value. Copyright American National Standards Institute Provided by IHS under license with A

38、NSI Not for ResaleNo reproduction or networking permitted without license from IHS-,-,-ISO/IEC 14496-14:2003(E) 2 ISO/IEC 2003 All rights reservedIn a transmitted bit-stream, the access units in the SL Packets are transmitted on byte boundaries. This means that hint tracks will construct SL Packet h

39、eaders using the information in the media tracks, and the hint tracks will reference the access units from the media track. The placement of the header during hinting is possible without bit shifting, as each SL Packet and corresponding contained access unit will both start on byte boundaries. 3.1.2

40、 Elementary Stream Descriptors The ESDescriptor for a stream within the scope of the MP4 file as described in this document is stored in the sample description and the fields and included structures are restricted as follows. ES_ID set to 0 as stored; when built into a stream, the lower 16 bits of t

41、he TrackID are used. streamDependenceFlag set to 0 as stored; if a dependency exists, it is indicated using a track reference of type dpnd. URLflag kept untouched, i.e. set to false, as the stream is in the file, not remote. SLConfigDescriptor is predefined type 2. OCRStreamFlag set to false in the

42、file. The ESDescriptor for a stream referenced through an ES URL is stored in the sample description and the fields and included structures are restricted as follows. ES_ID set to 0 as stored; when built into a stream, the lower 16 bits of the TrackID are used. streamDependenceFlag set to 0 as store

43、d; if a dependency exists, it is indicated using a track reference of type dpnd. URLflag kept untouched, i.e. set to true, as the stream is not in the file. SLConfigDescriptor kept untouched. OCRStreamFlag set to false in the file. Note that the QoSDescriptor also may need re-writing for transmissio

44、n as it contains information about PDU sizes etc. 3.1.3 Object Descriptors The initial object descriptor and object descriptor streams are handled specially within the file format. Object descriptors contain ES descriptors, which in turn contain stream specific information. In addition, to facilitat

45、e editing, the information about a track is stored as an ESDescriptor in the sample description within that track. It must be taken from there, re-written as appropriate, and transmitted as part of the OD stream when the presentation is streamed. As a consequence, ES descriptors are not stored withi

46、n the OD track or initial object descriptor. Instead, the initial object descriptor has a descriptor used only in the file, containing solely the track ID of the elementary stream. When used, an appropriately re-written ESDescriptor from the referenced track replaces this descriptor. Likewise, OD tr

47、acks are linked to ES tracks by track references. Where an ES descriptor would be used within the OD track, another descriptor is used, which again occurs only in the file. It contains the index into the set of mpod track references that this OD track owns. A suitably re-written ESDescriptor replace

48、s it by the hinting of this track. Copyright American National Standards Institute Provided by IHS under license with ANSI Not for ResaleNo reproduction or networking permitted without license from IHS-,-,-ISO/IEC 14496-14:2003(E) ISO/IEC 2003 All rights reserved 3The ES_ID_Inc is used in the Object Descriptor Box: class ES_ID_Inc extends BaseDescriptor : bit(8) tag=ES_IDIncTag unsigned int(32) Track_ID; / ID of the track to use ES_ID_IncTag = 0x0E is reserved for file format usage. The ES_ID_Ref is used in the OD stream: