SMPTE ST 382M-2007 Material Exchange Format Mapping AES3 and Broadcast Wave Audio into the MXF Generic Container.pdf

1、 Copyright 2007 by THE SOCIETY OF MOTION PICTURE AND TELEVISION ENGINEERS 595 W. Hartsdale Ave., White Plains, NY 10607 (914) 761-1100 Approved July 10, 2007 Table of Contents Page Foreword . 3 1 Scope 4 2 Conformance Notation 4 3 Normative References 4 4 Glossary of Acronyms, Terms and Data Types 5

2、 5 Introduction (Informative) 6 6 Packing of Audio Samples 6 6.1 Sample Validity 7 6.2 Division of Audio Essence into Frame-Wrapped Content 7 6.3 Division of Audio Essence into Clip-Wrapped Content Packages. 8 6.4 Custom Wrapped Audio Elements. 9 6.5 KLV Coding of Digital Audio Data Sound Elements 9

3、 6.5.1 Wave sound element key. 9 6.5.2 Essence element count Byte 14 10 6.5.3 Essence element type Byte 15 10 6.5.4 Essence element number Byte 16 10 6.5.5 Wave sound element length 10 6.5.6 Wave sound element value 10 6.6 Use of KAG 11 6.7 Optional Mapping of Material Package Tracks to Audio Channe

4、l IDs. 11 7 Carriage of BWF Metadata Chunks 11 7.1 General 11 7.2 Chunk. 11 7.2.1 Sound essence compression. 13 7.3 Broadcast Extension Chunk. 13 7.4 Other Chunks. 15 7.4.1 Peak envelope chunk 15 Page 1 of 41 pages SMPTE 382M-2007SMPTE STANDARD Material Exchange Format Mapping AES3 and Broadcast Wav

5、e Audio into the MXF Generic Container SMPTE 382M-2007 Page 2 of 41 pages 7.4.2 Quality chunk.15 7.4.3 Other chunks 15 7.4.4 Unknown chunks while MXF excoding.16 7.4.5 Use of a physical descriptor (Informative)16 8 Carriage of SMPTE 339M Time Stamp, V-Sync and User Data.16 9 Carriage of AES3 Channel

6、 Status Data and User Data.17 9.1 General.17 9.2 Block Start Offset17 9.3 Channel Status Data 17 9.3.1 Definition.17 9.3.2 Channel status data Minimum implementation17 9.3.3 Channel status data Standard implementation17 9.3.4 Channel status data Enhanced implementation 17 9.3.5 Optional mapping of c

7、hannel status data into MXF .18 9.4 User Data.19 10 SMPTE Label for Essence Container Identification 19 Annex A Definition of the Essence Descriptor Sets for the Essense Data Defined by this Standard (Normative)20 A.1 Wave Audio Essence Descriptor20 A.2 AES3 Audio Essence Descriptor22 A.3 Wave Audio

8、 Physical Descriptor23 A.4 Unknown Chunk Set 24 Annex B Example of Mapping Channels and Descriptors (Informative) .25 Annex C Comparison with Other Standards (Informative) 26 C.1 Comparison with SMPTE 302M and SMPTE 331M 26 C.2 Comparison with SMPTE 337M / SMPTE 338M / SMPTE 339M and Related Standar

9、ds26 Annex D Terminology Comparison with AES31-2 (Normative).27 D.1 Comparison of Data Type Definitions 27 D.2 Comparison of Chunk Fields .27 D.3 Comparison of Chunk Fields .28 Annex E Simple Audio Channel Mapping (Normative).30 E.1 Optional Mapping of Subchannels of Audio Elements to Material Packa

10、ge30 E.2 Optional Combination of Source Package Tracks .30 Annex F Mapping Multiple SMPTE 339M Time Stamps(Normative) 32 F.1 Association of SMPTE 337M data_dtream_number to Time Code Tracks .32 Annex G Peak Envelope Chunk (Normative) 33 G.1 Generation of the Peak Envelope Data .33 G.2 Definition of

11、the Peak Envelope Chunk.33 SMPTE 382M-2007 Page 3 of 41 pages Annex H Quality Chunk (Normative). 36 H.1 Syntax of Quality Chunk 36 H.2 Definition of Quality Chunk 36 H.3 Example of Quality Chunk. 39 Annex I Bibliography (Informative) 41 Foreword SMPTE (the Society of Motion Picture and Television En

12、gineers) is an internationally-recognized standards developing organization. Headquartered and incorporated in the United States of America, SMPTE has members in over 80 countries on six continents. SMPTEs Engineering Documents, including Standards, Recommended Practices and Engineering Guidelines,

13、are prepared by SMPTEs Technology Committees. Participation in these Committees is open to all with a bona fide interest in their work. SMPTE cooperates closely with other standards-developing organizations, including ISO, IEC and ITU. SMPTE Engineering Documents are drafted in accordance with the r

14、ules given in Part XIII of its Administrative Practices. SMPTE 382M was prepared by Technology Committee W25.SMPTE 382M-2007 Page 4 of 41 pages 1 Scope This standard defines the mapping of digital audio data, ancillary data and metadata from the broadcast wave format (BWF) and from AES3 digital audi

15、o data into sound essence elements, which can be included in an MXF generic container. The data carried in wave audio essence elements may be uncompressed PCM audio data, compressed data or raw data as in BWF, AES3 or SMPTE 337M carried in a single AES3 stream. Labels for the identification of uncom

16、pressed audio samples within this mapping are provided by this standard. Labels for compressed audio types can be added to the Labels Register defined by SMPTE 400M. In order to achieve interoperability within any given operational pattern, restrictions may be placed on the way in which this essence

17、 container can be implemented. The reader is advised to carefully study the appropriate operational pattern document before implementation. 2 Conformance Notation Normative text is text that describes elements of the design that are indispensable or contains the conformance language keywords: “shall

18、“, “should“, or “may“. Informative text is text that is potentially helpful to the user, but not indispensable, and can be removed, changed, or added editorially without affecting interoperability. Informative text does not contain any conformance keywords. All text in this document is, by default,

19、normative, except: the Introduction, any section explicitly labeled as “Informative“ or individual paragraphs that start with “Note:” The keywords “shall“ and “shall not“ indicate requirements strictly to be followed in order to conform to the document and from which no deviation is permitted. The k

20、eywords, “should“ and “should not“ indicate that, among several possibilities, one is recommended as particularly suitable, without mentioning or excluding others; or that a certain course of action is preferred but not necessarily required; or that (in the negative form) a certain possibility or co

21、urse of action is deprecated but not prohibited. The keywords “may“ and “need not“ indicate courses of action permissible within the limits of the document. The keyword “reserved” indicates a provision that is not defined at this time, shall not be used, and may be defined in the future. The keyword

22、 “forbidden” indicates “reserved” and in addition indicates that the provision will never be defined in the future. Unless otherwise specified the order of precedence of the types of normative information in this document shall be as follows. Normative prose shall be the authoritative definition. Ta

23、bles shall be next, followed by formal languages, then figures, and then any other language forms. 3 Normative References The following standards contain provisions which, through reference in this text, constitute provisions of this recommended practice. At the time of publication, the editions ind

24、icated were valid. All standards are subject to revision, and parties to agreements based on this recommended practice are encouraged to investigate the possibility of applying the most recent edition of the standards indicated below. SMPTE 337M-2000, Television Format for Non-PCM Audio and Data in

25、an AES3 Serial Digital Audio Interface SMPTE 338M-2000, Television Format for Non-PCM Audio and Data in AES3 Data Types SMPTE 382M-2007 Page 5 of 41 pages SMPTE 339M-2004, Television Format for Non-PCM Audio and Data in AES3 Generic Data Types SMPTE 377M-2004, Television Material Exchange Format (MX

26、F) File Format Specification SMPTE 379M-2004, Television Material Exchange Format (MXF) MXF Generic Container SMPTE 400M-2004, Television SMPTE Labels Structure AES3-2003, Serial Transmission Format for Two-Channel Linearly Represented Digital Audio Data AES31-2-2006, AES Standard on Network and Fil

27、e Transfer of Audio Audio-File Transfer and Exchange File Format for Transferring Digital Audio Data Between Systems of Different Type and Manufacture ITU-R BR.1352-2:2002, Broadcast Wave Format (BWF), Annex 1, Annex 1 Appendix 1 and 2, and Annex 3 4 Glossary of Acronyms, Terms and Data Types Explan

28、ations and definitions of the acronyms and terms can be found in the MXF file format specification document. A supplementary glossary of acronyms and terms is defined in SMPTE 379M. They are not repeated here to avoid any divergence of meaning. The following acronyms are used in this standard: AES A

29、udio Engineering Society BEXT The Broadcast Extension Chunk BWF1Broadcast Wave Format BWFF Broadcast Wave Format file as defined in AES31-2 CRCC Cyclic Redundancy Check Code LEVL The Peak Envelope (level) RIFF Chunk defined by Annex G PCM Pulse Code Modulation RIFF Resource Interchange File Format a

30、 generic file format consisting of a series of chunks, each composed of a 32-bit chunk identifier, a 32-bit length field, and a number of data bytes. QLTY The Capturing Report (quality) RIFF Chunk defined by Annex H The following additional terms apply to AES3. Refer to AES3 for the precise definiti

31、on. Subframe: fixed structure used to carry the information described in 4.1.1 and 4.1.2 of AES3. Frame: sequence of two successive and associated subframes as described in 4.1.2 of AES3. Block: a group of 192 consecutive frames. The start of a block is designated by a special subframe preamble. 1Th

32、e abbreviations BWFF and BWF co-exist in this standard due to the fact that references cited by this standard were developed at different times. The abbreviations have the same technical meaning. SMPTE 382M-2007 Page 6 of 41 pages The following additional data types apply to this standard: char A da

33、ta type comprising either a single ISO 7-bit character or a string of ISO 7-bit characters with the string length determined by the number in the brackets. Where brackets are specified as simply “ ”, the string length is variable and terminated by a zero value. In some geographic areas, strings of t

34、ype char may contain UTF-8 or Shift-JIS characters. 5 Introduction (Informative) This standard defines the mapping of digital audio data and ancillary data and metadata from broadcast wave format (BWF) files, and AES3 data streams into KLV-encoded sets for inclusion in MXF files. In common with othe

35、r body specifications, the principal mapping is of the essence, in this case samples of digital audio data, into KLV packets. These are called wave audio essence elements. This standard employs the same bit-by-bit packing of sample data as is used by BWF files. The sample data is packed on a frame-b

36、y-frame or clip-by-clip or 5-frame basis excluding all ancillary data. This is described in section 6. This standard defines wave audio essence elements which may be used as MXF essence containers in their own right or as elements in content packages within an MXF generic container, depending upon a

37、pplication requirements. The division of audio essence into elements is discussed in section 6.2. Data carried in wave audio essence elements may be uncompressed PCM audio data or compressed data, as defined in AES31-2, AES3 or SMPTE 337M carried in a single AES3 stream. The specific format is indic

38、ated by the Sound Essence Coding property, which is described in section 7.2.1. BWF defines metadata which applies to the entire clip. This standard maps this metadata into the MXF header metadata. This is described in section 7. This standard also describes the mapping of constant and time-varying

39、ancillary data and metadata from AES3 subframes and U and C bits into appropriate MXF data structures. This is described in section 9. NOTE Data can be lost if applications do not support the carriage of the broadcast wave metadata or AES metadata parameters that are not mapped to the MXF structural

40、 metadata. It is recommended that implementers and users ensure that descriptive metadata mappings or other mechanisms are available in applications which require this level of data integrity. This particularly applies to parameters such as unmapped BWFF chunk parameters as described in section 7.3.

41、 6 Packaging of Audio Samples This standard defines audio essence elements containing one, two or N channels. In a multiple-channel element, samples are interleaved in order of channel number. The top-level file package shall have one track per mapped wave audio essence stream. A material package ma

42、y have multiple tracks of type sound. Source Clips in the material package may reference a given channel or channels within the top-level file package by setting an optional Channel ID property to the channel number in the target track. When AES3 subframes are being mapped, the first subframe of a b

43、lock (i.e., that identified by a Z preamble) is first in every sample pair. All ancillary data, including the VUCP bits, are mapped to a wave audio essence element as part of the packing of audio samples. Section 6.1 considers the validity bit, while section 9 describes the handling of the user, cha

44、nnel status and parity data. SMPTE 382M-2007 Page 7 of 41 pages Each sample shall be carried in the smallest number of bytes necessary to completely contain the data, stored as a little-endian integer (least significant byte first). Data shall be aligned to the most significant bit, and unused bits

45、shall be set to zero. For example, 20 bit samples are carried in 3 bytes. The least significant 4 bits of the first (least significant) byte are set to zero. A decoder can determine the number of bytes from the essence descriptor using the formula given in section 7.2. NOTE AES31-2 provides addition

46、al details of the mapping of audio samples into data bytes. SMPTE 320M and SMPTE 323M provide definitions of commonly used assignments of multiple channels. ITU-R BR.1352 also has details of the mapping of audio samples into data bytes. MXF encoders should set the optional Channel Assignment propert

47、y of the Wave Audio Essence Descriptor (see Table A.1) to the appropriate Label from the SMPTE Labels Register (i.e., the register defined by SMPTE 400M) in order to describe specific channel assignments. This standard does not define the format of MXF essence containers or essence descriptors for b

48、ig-endian sound essence. 6.1 Sample Validity When formatted according to AES3, audio subframes include a channel validity (V) bit, which is set to one when the sample data is not suitable for conversion to an analog audio signal. When the validity bit is not present, applications shall process audio

49、 data as though the validity bit were set to zero. This data is not available in the packed wave audio essence elements data format, and all applications shall process audio data as though the validity bit were set to zero. NOTE SMPTE 314M section 4.6.2.1.3 describes an audio error code in DV-derived audio sample data. This error code is the most-negative value of the sample (8000h), and is used to indicate invalid samples. It is recommended that these samples be overwritten w