Universal Serial Bus Device Class Definition for Audio Data Formats
Release 2.0 May 31, 2006 6
Table of Contents
Scope of This Release.............................................................................................................2
Contributors............................................................................................................................2
Revision History.......................................................................................................................2
Table of Contents.....................................................................................................................6
List of Tables...........................................................................................................................7
List of Figures.........................................................................................................................8
List of Figures.........................................................................................................................8
1 Introduction......................................................................................................................9
1.1 Related Documents.....................................................................................................9
1.2 Terms and Abbreviations.............................................................................................9
2 Audio Data Formats........................................................................................................11
2.1 Transfer Delimiter......................................................................................................12
2.2 Virtual Frame and Virtual Frame Packet Definitions.................................................13
2.3 Simple Audio Data Formats.......................................................................................13
2.3.1 Type I Formats...................................................................................................13
2.3.2 Type II Formats..................................................................................................17
2.3.3 Type III Formats.................................................................................................19
2.3.4 Type IV Formats.................................................................................................20
2.4 Extended Audio Data Formats..................................................................................21
2.4.1 Extended Type I Formats...................................................................................21
2.4.2 Extended Type II Formats..................................................................................23
2.4.3 Extended Type III Formats.................................................................................24
2.4.4 Side Band Protocols...........................................................................................25
3 Adding New Audio Data Formats..................................................................................27
4 Adding New Side Band Protocols.................................................................................28
Appendix A. Additional Audio Device Class Codes....................................................29
A.1 Format Type Codes...................................................................................................29
A.2 Audio Data Format Bit Allocation in the bmFormats field..........................................29
A.2.1 Audio Data Format Type I Bit Allocations..........................................................29
A.2.2 Audio Data Format Type II Bit Allocations.........................................................29
A.2.3 Audio Data Format Type III Bit Allocations........................................................30
A.2.4 Audio Data Format Type IV Bit Allocations........................................................30
A.3 Side Band Protocol Codes........................................................................................31
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Universal Serial Bus Device Class Definition for Audio Data Formats
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List of Tables
Table 2-1: Packetization........................................................................................................14
Table 2-2: Type I Format Type Descriptor...........................................................................15
Table 2-3: Type II Format Type Descriptor..........................................................................18
Table 2-4: Type III Format Type Descriptor.........................................................................20
Table 2-5: Type IV Format Type Descriptor.........................................................................21
Table 2-6: Extended Type I Format Type Descriptor..........................................................22
Table 2-7: Extended Type II Format Type Descriptor.........................................................23
Table 2-8: Extended Type III Format Type Descriptor........................................................25
Table 2-9: Hi-Res Presentation TimeStamp Layout............................................................25
Table A-1: Format Type Codes.............................................................................................29
Table A-2: Audio Data Format Type I Bit Allocations.........................................................29
Table A-3: Audio Data Format Type II Bit Allocations........................................................29
Table A-4: Audio Data Format Type III Bit Allocations.......................................................30
Table A-5: Audio Data Format Type IV Bit Allocations......................................................30
Table A-6: Side Band Protocol Codes.................................................................................31
Universal Serial Bus Device Class Definition for Audio Data Formats
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List of Figures
Figure 2-1: Type I Audio Stream...........................................................................................11
Figure 2-2: Type II Audio Stream..........................................................................................12
Figure 2-3: Extended Type I Format.....................................................................................22
Figure 2-4: Extended Type II Format....................................................................................23
Figure 2-5: Extended Type III Format...................................................................................24
Universal Serial Bus Device Class Definition for Audio Data Formats
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1 Introduction
The intention of this document is to describe in detail all the Audio Data Formats that are supported by the Audio Device Class. This document is considered an integral part of the Audio Device Class Specification, although subsequent revisions of this document are independent of the revision evolution of the main USB Audio Specification. This is to easily accommodate the addition of new Audio Data Formats without impeding the core USB Audio Specification.
1.1 Related Documents
• Universal Serial Bus Specification, Revision 2.0 (referred to in this document as the USB Specification). In particular, see Chapter 5, “USB Data Flow Model” and Chapter 9, “USB Device Framework.”
• Universal Serial Bus Device Class Definition for Audio Devices (referred to in this document as USB Audio Device Class).
• Universal Serial Bus Device Class Definition for Terminal Types (referred to in this document as USB Audio Terminal Types).
• ANSI S1.11-1986 standard.
• MPEG-1 standard ISO/IEC 111172-3 1993. (available from
http://www.iso.ch )
• MPEG-2 standard ISO/IEC 13818-3 Feb. 20, 1997. (available from
http://www.iso.ch )
• Digital Audio Compression Standard (AC-3), ATSC A/52A Aug. 20, 2001. (available from
http://www.atsc.org )
• Windows Media Audio (WMA) specification. (available from
http://www.microsoft.com)
• ANSI/IEEE-754 floating-point standard.
• ISO/IEC 60958 International Standard: Digital Audio Interface and Annexes.
• ISO/IEC 61937 standard.
• ITU G.711 standard.
• ETSI Specification TS 102 114, “DTS Coherent Acoustics; Core and Extensions”. (Available from
http://webapp.etsi.org/action%5CPU/20020827/ts_102114v010101p.pdf)
1.2 Terms and Abbreviations
This section defines terms used throughout this document. For additional terms that pertain to the Universal Serial Bus, see Chapter 2, “Terms and Abbreviations,” in the USB Specification.
AC-3 Audio compression standard from Dolby Labs.
Audio Slot A collection of audio subslots, each containing a PCM audio sample of a different physical audio channel, taken at the same moment in time.
Audio Stream A concatenation of a potentially very large number of audio slots ordered according to ascending time.
Audio Subslot Holds a single PCM audio sample.
DTS Acronym for Digital Theater Systems.
DVD Acronym for Digital Versatile Disc.
Encoded Audio Bit Stream A concatenation of a potentially very large number of encoded audio frames, ordered according to ascending time.
Encoded Audio Frame A sequence of bits that contains an encoded representation of audio samples from one or more physical audio channels taken over a fixed period of time.
Universal Serial Bus Device Class Definition for Audio Data Formats
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MPEG Acronym for Moving Pictures Expert Group.
PCM Acronym for Pulse Coded Modulation.
Virtual Frame A grouping of USB (micro)frames that are related.
Virtual Frame Packet A packet that contains all the audio slots that are transferred over the bus during a virtual frame.
Transfer Delimiter A unique token that indicates an interruption in an isochronous data packet stream. Can be either a zero-length data packet or the absence of an isochronous transfer in a certain USB frame.
WMA Acronym for Windows Media Audio.
最終更新：2011年06月04日 17:58
