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Offset Field Size Value Description
1 bDescriptorType 1 0x24 CS_INTERFACE.
2 bDescriptorSubtype 1 0x03 OUTPUT_TERMINAL subtype.
3 bTerminalID 1 0x06 ID of this Terminal.
4 wTerminalType 2 0x0101 Terminal is USB Streaming Out.
6 bAssocTerminal 1 0x03 Associated with USB Streaming In
Terminal.
7 bSourceID 1 0x09 From USB Selector Unit.
8 iTerminal 1 0x00 Unused.
C.3.3.9 Selector Unit Descriptor (ID7)
This descriptor describes the Selector Unit connected to the Phone Line Out Output Terminal. Either
Handset In or USB In signals can be selected.
Table C-11: USB Telephone Selector Unit Descriptor (ID7)
Offset Field Size Value Description
0 bLength 1 0x09 Size of this descriptor, in bytes.
1 bDescriptorType 1 0x24 CS_INTERFACE.
2 bDescriptorSubtype 1 0x05 SELECTOR_UNIT subtype.
3 bUnitD 1 0x07 ID of this Unit.
4 bNrInPins 1 0x02 Number of input pins.
6 baSourceID(1) 1 0x02 From Handset In Terminal.
7 baSourceID(2) 1 0x03 From USB Streaming In Terminal.
8 iSelector 1 0x00 Unused.
C.3.3.10 Selector Unit Descriptor (ID8)
This descriptor describes the Selector Unit connected to the Handset Out Output Terminal. Either Phone
Line In or USB In signals can be selected.
Table C-12: USB Telephone Selector Unit Descriptor (ID8)
Offset Field Size Value Description
0 bLength 1 0x09 Size of this descriptor, in bytes.
1 bDescriptorType 1 0x24 CS_INTERFACE.
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Offset Field Size Value Description
2 bDescriptorSubtype 1 0x05 SELECTOR_UNIT subtype.
3 bUnitD 1 0x08 ID of this Unit.
4 bNrInPins 1 0x02 Number of input pins.
6 baSourceID(1) 1 0x01 From Phone Line In Terminal.
7 baSourceID(2) 1 0x03 From USB Streaming In Terminal.
8 iSelector 1 0x00 Unused.
C.3.3.11 Selector Unit Descriptor (ID9)
This descriptor describes the Selector Unit connected to the USB Streaming Out Output Terminal. Either
Phone Line In or Handset In signals can be selected.
Table C-13: USB Telephone Selector Unit Descriptor (ID9)
Offset Field Size Value Description
0 bLength 1 0x09 Size of this descriptor, in bytes.
1 bDescriptorType 1 0x24 CS_INTERFACE.
2 bDescriptorSubtype 1 0x05 SELECTOR_UNIT subtype.
3 bUnitD 1 0x09 ID of this Unit
4 bNrInPins 1 0x02 Number of input pins.
6 baSourceID(1) 1 0x01 From Phone Line In Terminal.
7 baSourceID(2) 1 0x02 From Handset In Terminal.
8 iSelector 1 0x00 Unused.
C.3.4 AudioStreaming Interface 1 Descriptor
The AudioStreaming interface 1 is used for streaming audio from the Host to the USB Telephone device.
AudioStreaming interface 1 has two alternate settings. The first is the zero bandwidth alternate setting
(Alternate Setting 0), used to reclaim USB bandwidth. It is also the default alternate setting. The second
alternate setting (1) is the fully operational setting for the Host to Device streaming communication.
C.3.4.1 Zero-bandwidth Alternate Setting 0
C.3.4.1.1.1 Standard Interface Descriptor
USB Device Class Definition for Audio Devices
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Table C-14: USB Telephone Standard Interface Descriptor (Alt. Set. 0)
Offset Field Size Value Description
0 bLength 1 0x09 Size of this descriptor, in bytes.
1 bDescriptorType 1 0x04 INTERFACE descriptor.
2 bInterfaceNumber 1 0x01 Index of this interface.
3 bAlternateSetting 1 0x00 Index of this setting.
4 bNumEndpoints 1 0x00 0 endpoints.
5 bInterfaceClass 1 0x01 AUDIO.
6 bInterfaceSubclass 1 0x02 AUDIO_STREAMING.
7 bInterfaceProtocol 1 0x00 Unused.
8 iInterface 1 0x00 Unused.
C.3.4.2 Operational Alternate Setting 1
C.3.4.2.1.1 Standard AS Interface Descriptor
Table C-15: USB Telephone Standard AS Interface Descriptor
Offset Field Size Value Description
0 bLength 1 0x09 Size of this descriptor, in bytes.
1 bDescriptorType 1 0x04 INTERFACE descriptor.
2 bInterfaceNumber 1 0x01 Index of this interface.
3 bAlternateSetting 1 0x01 Index of this setting.
4 bNumEndpoints 1 0x01 1 endpoint.
5 bInterfaceClass 1 0x01 AUDIO.
6 bInterfaceSubclass 1 0x02 AUDIO_STREAMING.
7 bInterfaceProtocol 1 0x00 Unused.
8 iInterface 1 0x00 Unused.
C.3.4.2.1.2 Class-specific AS Interface Descriptor
Table C-16: USB Telephone Class-specific AS Interface Descriptor
Offset Field Size Value Description
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Offset Field Size Value Description
0 bLength 1 0x07 Size of this descriptor, in bytes.
1 bDescriptorType 1 0x24 CS_INTERFACE descriptor.
2 bDescriptorSubtype 1 0x01 GENERAL.
3 bTerminalLink 1 0x03 Linked to USB Streaming In Terminal.
4 bDelay 1 0x01 Interface delay.
5 wFormatTag 2 0x0001 PCM format.
C.3.4.2.1.3 Type I Format Type Descriptor
Table C-17: USB Telephone Type I Format Type Descriptor
Offset Field Size Value Description
0 bLength 1 0x0B Size of this descriptor, in bytes.
1 bDescriptorType 1 0x24 CS_INTERFACE.
2 bDescriptorSubtype 1 0x02 FORMAT_TYPE.
3 bFormatType 1 0x01 FORMAT_TYPE_I.
4 bNrChannels 1 0x01 One channel.
5 bSubFrameSize 1 0x02 Two bytes per slot.
6 bBitResolution 1 0x10 16 bits.
7 bSamFreqType 1 0x01 One sampling frequency.
8 tSamFreq 3 0x01F40 8000Hz is the sampling frequency.
C.3.4.2.1.4 Standard Endpoint Descriptor
Table C-18: USB Telephone Standard Endpoint Descriptor
Offset Field Size Value Description
0 bLength 1 0x09 Size of this descriptor, in bytes.
1 bDescriptorType 1 0x05 ENDPOINT descriptor.
2 bEndpointAddress 1 0x01 OUT Endpoint 1.
3 bmAttributes 1 0x0B Isochronous transfer type, synchronous
synchronization type.
4 wMaxPacketSize 2 0x0010 16 bytes per packet (8 two-byte
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Offset Field Size Value Description
samples).
6 bInterval 1 0x01 One packet every frame.
7 bRefresh 1 0x00 Unused.
8 bSynchAddress 1 0x00 Unused.
C.3.4.2.1.5 Class-specific Isochronous Audio Data Endpoint Descriptor
Table C-19: USB Telephone Class-specific Isoc. Audio Data Endpoint Descriptor
Offset Field Size Value Description
0 bLength 1 0x07 Size of this descriptor, in bytes.
1 bDescriptorType 1 0x25 CS_ENDPOINT.
2 bDescriptorSubtype 1 0x01 GENERAL.
3 bmAttributes 1 0x00 No sampling frequency control, no pitch
control.
4 bLockDelayUnits 1 0x00 Unused.
5 wLockDelay 2 0x0000 Unused.
C.3.5 AudioStreaming Interface 2 Descriptor
The AudioStreaming interface 2 is used for streaming audio from the USB Telephone device to the Host.
AudioStreaming interface 2 has two alternate settings. The first is the zero bandwidth alternate setting
(Alternate Setting 0), used to reclaim USB bandwidth. It is also the default alternate setting. The second
alternate setting (1) is the fully operational setting for the Device to Host streaming communication.
C.3.5.1 Zero-bandwidth Alternate Setting 0
C.3.5.1.1.1 Standard Interface Descriptor
Table C-20: USB Telephone Standard Interface Descriptor (Alt. Set. 0)
Offset Field Size Value Description
0 bLength 1 0x09 Size of this descriptor, in bytes.
1 bDescriptorType 1 0x04 INTERFACE descriptor.
2 bInterfaceNumber 1 0x01 Index of this interface.
3 bAlternateSetting 1 0x00 Index of this setting.
4 bNumEndpoints 1 0x00 0 endpoints.
最終更新：2011年05月02日 03:36
