USB Device Class Definition for Audio Devices
Release 1.0 March 18, 1998 xi
Table A-18: Extension Unit Control Selectors ...............................................................104
Table A-19: Endpoint Control Selectors ........................................................................104
Table B-1: USB Microphone Device Descriptor.............................................................106
Table B-2: USB Microphone Configuration Descriptor .................................................107
Table B-3: USB Microphone Standard AC Interface Descriptor....................................107
Table B-4: USB Microphone Class-specific AC Interface Descriptor ...........................108
Table B-5: USB Microphone Input Terminal Descriptor................................................109
Table B-6: USB Microphone Output Terminal Descriptor.............................................109
Table B-7: USB Microphone Standard AS Interface Descriptor (Alt. Set. 0) ................110
Table B-8: USB Microphone Standard AS Interface Descriptor....................................110
Table B-9: USB Microphone Class-specific AS General Interface Descriptor .............111
Table B-10: USB Microphone Type I Format Type Descriptor......................................111
Table B-11: USB Microphone Standard Endpoint Descriptor.......................................112
Table B-12: USB Microphone Class-specific Isoc. Audio Data Endpoint Descriptor ..112
Table B-13: USB Microphone Manufacturer String Descriptor.....................................112
Table B-14: USB Microphone Product String Descriptor..............................................113
Table C-1: USB Telephone Device Descriptor ...............................................................115
Table C-2: USB Telephone Configuration Descriptor ...................................................116
Table C-3: USB Telephone Standard AC Interface Descriptor......................................117
Table C-4: USB Telephone Class-specific Interface Descriptor ...................................117
Table C-5: USB Telephone Input Terminal Descriptor (ID1) .........................................118
Table C-6: USB Telephone Input Terminal Descriptor (ID2) .........................................118
Table C-7: USB Telephone Input Terminal Descriptor (ID3) .........................................119
Table C-8: USB Telephone Output Terminal Descriptor (ID4) ......................................119
Table C-9: USB Telephone Output Terminal Descriptor (ID5) ......................................120
Table C-10: USB Telephone Output Terminal Descriptor (ID6) ....................................120
Table C-11: USB Telephone Selector Unit Descriptor (ID7) ..........................................121
Table C-12: USB Telephone Selector Unit Descriptor (ID8) ..........................................121
Table C-13: USB Telephone Selector Unit Descriptor (ID9) ..........................................122
Table C-14: USB Telephone Standard Interface Descriptor (Alt. Set. 0).......................123
Table C-15: USB Telephone Standard AS Interface Descriptor ....................................123
Table C-16: USB Telephone Class-specific AS Interface Descriptor............................123
Table C-17: USB Telephone Type I Format Type Descriptor ........................................124
Table C-18: USB Telephone Standard Endpoint Descriptor.........................................124
Table C-19: USB Telephone Class-specific Isoc. Audio Data Endpoint Descriptor ....125
USB Device Class Definition for Audio Devices
Release 1.0 March 18, 1998 xii
Table C-20: USB Telephone Standard Interface Descriptor (Alt. Set. 0).......................125
Table C-21: USB Telephone Standard AS Interface Descriptor ....................................126
Table C-22: USB Telephone Class-specific AS Interface Descriptor............................126
Table C-23: USB Telephone Type I format type descriptor...........................................127
Table C-24: USB Telephone Standard Endpoint descriptor .........................................127
Table C-25: USB Telephone Class-specific Isoc. Audio Data Endpoint Descriptor ....127
Table C-26: USB Telephone Manufacturer String Descriptor .......................................128
Table C-27: USB Telephone Product String Descriptor ................................................128
Table 5-28: Set Interface Request Values.......................................................................129
Table C-29: Set Selector Unit Control Request Values .................................................129
Table C-30: Get Selector Unit Control Request Values.................................................130
USB Device Class Definition for Audio Devices
Release 1.0 March 18, 1998 xiii
List of Figures
Figure 3-1: Input Terminal Icon ........................................................................................21
Figure 3-2: Output Terminal Icon .....................................................................................22
Figure 3-3: Mixer Unit Icon................................................................................................22
Figure 3-4: Selector Unit Icon ...........................................................................................23
Figure 3-5: Feature Unit Icon ............................................................................................23
Figure 3-6: Up/Down-mix Processing Unit Icon...............................................................24
Figure 3-7: Dolby Prologic Processing Unit Icon ............................................................25
Figure 3-8: 3D-Stereo Extender Processing Unit Icon.....................................................25
Figure 3-9: Reverberation Processing Unit Icon..............................................................26
Figure 3-10: Chorus Processing Unit Icon.......................................................................26
Figure 3-11: Dynamic Range Compressor Transfer Characteristic ................................27
Figure 3-12: Dynamic Range Compressor Processing Unit Icon ...................................27
Figure 3-13: Extension Unit Icon ......................................................................................28
Figure B-1: USB Microphone Topology .........................................................................105
Figure B-2: USB Microphone Descriptor Hierarchy.......................................................106
Figure C-1: USB Telephone Topology ...........................................................................114
Figure C-2: USB Telephone Descriptor Hierarchy.........................................................115
USB Device Class Definition for Audio Devices
Release 1.0 March 18, 1998 14
1 Introduction
1.1 Scope
The Audio Device Class Definition applies to all devices or functions embedded in composite devices that are used to manipulate audio, voice, and sound-related functionality. This includes both audio data (analog and digital) and the functionality that is used to directly control the audio environment, such as Volume and Tone Control. The Audio Device Class does not include functionality to operate transport mechanisms that are related to the reproduction of audio data, such as tape transport mechanisms or CDROM drive control. Handling of MIDI data streams over the USB is directly related to audio and thus covered in this document.
1.2 Purpose
The purpose of this document is to describe the minimum capabilities and characteristics an audio device must support to comply with the USB. This document also provides recommendations for optional
features.
1.3 Related Documents
· Universal Serial Bus Specification, 1.0 final draft revision (also referred to as the USB Specification). In particular, see Section 9, “USB Device Framework.”
· Universal Serial Bus Device Class Definition for Audio Data Formats (referred to in this document as USB Audio Data Formats).
· 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.
· MPEG-2 standard ISO/IEC 13818-3 Feb. 20, 1997.
· Digital Audio Compression Standard (AC-3), ATSC A/52 Dec. 20, 1995. (available from
http://www.atsc.org)
· ANSI/IEEE-754 floating-point standard.
· ISO/IEC 958 International Standard: Digital Audio Interface and Annexes.
· ISO/IEC 1937 standard.
· ITU G.711 standard.
1.4 Terms and Abbreviations
This section defines terms used throughout this document. For additional terms that pertain to the Universal Serial Bus, see Section 2, “Terms and Abbreviations,” in the USB Specification.
Audio Channel Cluster Group of logical audio channels that carry tightly related synchronous audio information. A stereo audio stream is a typical example of a two-channel audio channel cluster.
Audio Control Attribute Parameter of an Audio Control. Examples are Current, Minimum, Maximum and Resolution attributes of a Volume Control.
Audio Control Logical object that is used to manipulate a specific audio property. Examples are Volume Control, Mute Control, etc.
Audio data stream Transport medium that can carry audio information.
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Audio Function Independent part of a USB device that deals with audiorelated functionality.
Audio Interface Collection (AIC) Grouping of a single AudioControl interface, zero or more AudioStreaming interfaces and zero or more
MIDIStreaming interfaces that together constitute a complete interface to an audio function.
AudioControl interface (ACI) USB interface used to access the Audio Controls inside an audio function.
AudioStreaming interface (ASI) USB interface used to transport audio streams into or out of the audio function.
Entity Addressable logical object inside an audio function.
Extension Unit (XU) Applies an undefined process to a number of logical input channels.
Feature Unit (FU) Provides basic audio manipulation on the incoming logical audio channels.
FUD Acronym for Feature Unit Descriptor.
Input Pin Logical input connection to an Entity. Carries a single audio channel cluster.
Input Terminal (IT) Receptacle for audio information flowing into the audio function.
ITD Acronym for Input Terminal Descriptor.
Logical Audio Channel Logical transport medium for a single audio channel. Makes abstraction of the physical properties and formats of the connection. Is usually identified by spatial location. Examples are Left channel, Right Surround channel, etc.
MIDIStreaming interface (MSI) USB interface used to transport MIDI data streams into or out of the audio function.
Mixer Unit (MU) Mixes a number of logical input channels into a number of logical output channels.
MUD Acronym for Mixer Unit Descriptor.
OTD Acronym for Output Terminal Descriptor.
Output Pin Logical output connection to an Entity. Carries a single audio channel cluster.
Output Terminal (OT) An outlet for audio information flowing out of the audio function.
Processing Unit (PU) Applies a predefined process to a number of logical input channels.
PUD Acronym for Processing Unit Descriptor.
Selector Unit (SU) Selects from a number of input audio channel clusters.
SUD Acronym for Selector Unit Descriptor.
最終更新：2011年05月22日 10:13
