My question is quite similar to this question: Link, but i am not allowed to comment.
I'm implementing a PIC32 as a soundcard, and i now have a working USB audio stream, supporting 16-bit at 32kHz and 48kHz sample rates. I now want to change the bit depth to 24-bit, so i change my USB Descriptors to:
bSubFrameSize = 0x03, // 3 bytes per sample
bBitResolution = 0x18, // 24-bit resolution
When i do this, he bit resolution is changed as it is suppose to, but in the properties of the microphone, the dropdown menu where i could change the sampling frequency is grey. I havn't changed anything in the endpoint descriptors, where both 32kHz and 48kHz still is supported.
My USB topology has 1 Audio control interface with a couple of Units, and 2 Audio Streaming Interfaces, for streaming IN and OUT.
Marc O answered his question by saying that something in his Input Terminal, i have tried changing wChannelConfig but i doesn't work.
I have tried Uninstalling and Installing the device drivers, but doesn't work.
What more do i need to change in the descriptors, to be able to select the sampling Frequency?
Thanks :)
Edit: Added Descriptor code and descriped progress
When i changed the no of channels to 2, and made the wChannelConfig = 0x03 -> right + Left Front, i saw the the field on he picture change to: "2 channel, 24 bit, 48000 Hz (Studio Quality)", but it still didn't make the dropdown menu white, and i couldn't change sample rate.
Below i've added the Audio funcion descriptors:
//CD
0x09, // Size : 9 Bytes
USB_DESCRIPTOR_CONFIGURATION, // Configuration Descriptor (0x02)
0x10, // Total length in bytes of data returned
0x01, // 2. Byte af Total Length
0x05, // Number of Interfaces: 5 3 Audio + 2 Comm
0x01, // Configuration Value, Value to use as an argument to select this configuration
0x00, // iConfiguration, Index of String Descriptor describing this configuration
_DEFAULT | _SELF, // bmAttributes, selfpowered
0xFA, // Maximum Power : 250 mA
// ######## Audio Control Interface Descriptor
//ID - Interface Descriptor
0x09, // Size : 9 Bytes
USB_DESCRIPTOR_INTERFACE, // Interface Descriptor (0x04)
0x00, // Number of Interface: Interface nr 0
0x00, // Value used to select alternative setting
0x00, // Number of Endpoints used for this interface, 0
AUDIO_DEVICE, // Class Code (Assigned by USB Org), AUDIO
AUDIOCONTROL, // Subclass Code (Assigned by USB Org), AUDIOCONTROL
0x00, // Protocol Code (Assigned by USB Org)
0x00, // Index of String Descriptor Describing this interface
// HEADER
0x0A, // Size : 10 Bytes
CS_INTERFACE, // CS_INTERFACE Descriptor Type
HEADER, // HEADER descriptor subtype
0x00,0x01, // Audio Device compliant to the USB Audio specification version 1.00
0x46,0x00, // 64 bytes - Total number of bytes returned for the class-specific AudioControl interface descriptor. // Includes the combined length of this descriptor header and all Unit and Terminal descriptors.
0x02, // bInCollection -> Number of streaming interfaces = 2
0x01, // en form for index: "AudioStreaming interface 1 belongs to this AudioControl interface."
0x02, // beskriver nok streaming interface 2's index
// INPUT_TERMINAL ID = 1 USB Stream
0x0B, // size : 12 bytes
CS_INTERFACE, // CS_INTERFACE Descriptor Type
INPUT_TERMINAL, // INPUT_TERMINAL - Descriptor subtype = 2
INPUT_TER_USB, // ID of this Input Terminal. // Constant uniquely identifying the Terminal within the audio function.
USB_STREAMING, // wTerminalType -> 0x0101 = USB streamming
0x00, // bAssocTerminal -> 0x00 = No association.
0x02, // bNrChannels -> 0x01 two channel.
0x03, // wChannelConfig -> 0x03 = right + Left Front
0x00, // iChannelNames -> 0x00 = Unused.
0x00, // iTerminal -> 0x00 = Unused.
// INPUT_TERMINAL ID = 4 MICROPHONE
0x0B, // size : 12 bytes
CS_INTERFACE, // CS_INTERFACE Descriptor Type
INPUT_TERMINAL, // INPUT_TERMINAL - Descriptor subtype
INPUT_TER_MIC, // bTerminalID -> ID of this Input Terminal = 4
MICROPHONE, // wTerminalType -> 0x0201 = Microphone
0x00, // bAssocTerminal -> 0x00 = No association.
0x02, // bNrChannels -> 0x01 one channel.
0x03, // wChannelConfig -> 0x03 = right + Left Front
0x00, // iChannelNames -> 0x00 = Unused.
0x00, // iTerminal -> 0x00 = Unused.
// OUTPUT_TERMINAL ID = 3 SPEAKER
0x09, // size : 9 Bytes
CS_INTERFACE, // CS_INTERFACE Descriptor Type
OUTPUT_TERMINAL, // OUTPUT_TERMINAL - Descriptor subtype
OUTPUT_TER_SPEAK, // bTerminalID -> ID of this Output Terminal = 3
SPEAKER, // wTerminalType -> 0x0301 = Speaker
0x00, // bAssocTerminal -> 0x00 = Unused
FEATURE_OUT, // bSourceID -> 0x02 = From Input Terminal ID 2 = USB stream
0x00, // iTerminal -> 0x00 = Unused.
// OUTPUT_TERMINAL ID = 6 USB Stream
0x09, // Size : 9 Bytes
CS_INTERFACE, // CS_INTERFACE Descriptor Type
OUTPUT_TERMINAL, // OUTPUT_TERMINAL - Descriptor subtype
OUTPUT_TER_USB, // bTerminalID -> ID of this Output Terminal = 6
USB_STREAMING, // wTerminalType -> 0x0101 = USB streaming
0x00, // bAssocTerminal -> 0x00 = Unused
FEATURE_IN, // bSourceID -> 0x05 = Feature Unit that sets IN features SOURCE = 5 (Feature_IN)
0x00, // iTerminal -> 0x00 = Unused.
// FEATURE_UNIT ID = 2
0x0A, // Size : 10 Bytes
CS_INTERFACE, // CS_INTERFACE Descriptor Type
FEATURE_UNIT, // FEATURE_UNIT - Descriptor subtype
FEATURE_OUT, // bUnitID -> ID 2
INPUT_TER_USB, // bSourceID -> 0x01 = connected to Input Terminal 1 SOURCE = 1 (Input USB)
0x01, // bControlSize -> 0x01 = 1 Byte
0x03, // bmaControls(n = channel nr) -> 0x03 = Mute + volume
0x03, // bmaControls(n = channel nr) -> 0x03 = Mute + volume
0x00, // bmaControls(n = channel nr) -> 0x00 = no master control
0x00, // iFeature -> string Descriptor Unused
// FEATURE_UNIT ID = 5
0x0A, // Size : 9 Bytes
CS_INTERFACE, // CS_INTERFACE Descriptor Type
FEATURE_UNIT, // FEATURE_UNIT - Descriptor subtype
FEATURE_IN, // bUnitID -> ID 5
INPUT_TER_MIC, // bSourceID -> 0x04 = Connected to Unit ID 4 SOURCE = 4 (Input Mic.)
0x01, // bControlSize -> 0x01 = 1 Byte
0x03, // bmaControls(1) -> 0b0000011 = Mute + Volume no. of Channels +1 = no. of bmaControls
0x03, // bmaControls(2) -> 0b0000011 = Mute + Volume no. of Channels +1 = no. of bmaControls
0x00, // bmaControls(3) -> 0x00 = No controls supperted no. of Channels +1 = no. of bmaControls
0x00, // iFeature -> string Descriptor Unused
// ######## AUDIO STREAM INTERFACE 1 OUT SPEAKER
//ID // Alternate Setting 0 - 0 endpoint
0x09, // Size : 9 Bytes
USB_DESCRIPTOR_INTERFACE, // Interface Descriptor (0x04)
0x01, // bInterfaceNumber -> 0x01 Interface ID = 1
0x00, // bAlternateSetting -> 0x00 = index of this interface's alternate setting
0x00, // bNumEndpoints -> 0x00 = 0 Endpoints to this interface
AUDIO_DEVICE, // bInterfaceClass -> 0x01 = Audio Interface
AUDIOSTREAMING, // bInterfaceSubclass -> 0x02 = AUDIO_STREAMING
0x00, // bInterfaceProtocol -> 0x00 = Unused
0x00, // iInterface -> 0x00 = Unused
//ID // Alternate Setting 1 - 1 endpoint
0x09, // Size : 9 Bytes
USB_DESCRIPTOR_INTERFACE, // Interface Descriptor (0x04)
0x01, // bInterfaceNumber -> 0x01 Interface ID = 1
0x01, // bAlternateSetting -> 0x01 = index of this interface's alternate setting
0x01, // bNumEndpoints -> 0x01 = 1 Endpoints to this interface
0x01, // bInterfaceClass -> 0x01 = Audio Interface
0x02, // bInterfaceSubclass -> 0x02 = AUDIO_STREAMING
0x00, // bInterfaceProtocol -> 0x00 = Unused
0x00, // iInterface -> 0x00 = Unused
// ASID GENERAL
0x07, // Size : 7 Bytes
CS_INTERFACE, // CS_INTERFACE Descriptor Type
AS_GENERAL, // bDescriptorSubtype -> 0x01 = GENERAL subtype
0x01, // bTerminalLink -> 0x01 = The Terminal ID of the Terminal to which the endpoint of this interface is connected.
0x01, // bDelay -> 0x01 = Delay (delta) introduced by the data path (see Section 3.4, ?Inter Channel Synchronization? - in Audio Devices). Expressed in number of frames.
0x01,0x00, // wFormatTag -> 0x0001 = PCM
// ASID FORMAT_TYPE
0x0E, // Size : 14 Bytes
CS_INTERFACE, // CS_INTERFACE Descriptor Type
FORMAT_TYPE, // bDescriptorSubtype -> 0x02 = FORMAT_TYPE
0x01, // bFormatType -> 0x01 = FORMAT_TYPE_I -> ref: A.1.1 Audio Data Format Type I Codes -> Audio Data Format Dok
0x02, // bNrChannels -> 0x02 = Two channels
BYTES_PR_SAMPLE, // bSubFrameSize -> 0x03 = 3 bytes pr audio subframe
BIT_RESOLUTION, // bBitResolution -> 0x18 = 24 bit pr sample
0x02, // bSamFreqType -> 0x02 = 2 sample frequencies supported
0x00,0x7D,0x00, // tSamFreq -> 0x7D00 = 32000 Hz
0x80,0xBB,0x00, // tSamFreq -> 0xBB80 = 48000 Hz
//ED ENDPOINT OUT
0x09, // Size : 9 Bytes
USB_DESCRIPTOR_ENDPOINT, // 0x05 -> ENDPOINT Descriptor Type
0x01, // bEndpointAddress -> 0x01 = adress 1, OUT, -> ref 9.6.6 Endpoint -> usb_20 Dok
0x09, // bmAttributes -> 0b00001001 -> Bits 0-1 = 01 = Isochronous , Bits 2-3 = 10 = Adaptive
AUDIO_MAX_SAMPLES * sizeof ( AUDIO_PLAY_SAMPLE ), AUDIO_MAX_SAMPLES * sizeof ( AUDIO_PLAY_SAMPLE )>>8,
0x01, // bInterval -> 0x01 = 1 millisecond
0x00, // Unused
0x00, // Unused
//AS ENDPOINT
0x07, // Size : 7 Bytes
CS_ENDPOINT, // CS_ENDPOINT
EP_GENERAL, // bDescriptorSubtype -> 0x01 = GENERAL
SAMPLING_FREQ_CONTROL, // bmAttributes -> 0b00000001 = Bit 1 = 1 => Sample Freq Control is supported by this endpoint
0x00, // bLockDelayUnits -> 0x00 = Indicates the units used for the wLockDelay field: 0 = Undefined
0x00,0x00, // the time it takes this endpoint to reliably lock its internal clock recovery circuitry.
// ######## AUDIO STREAM INTERFACE 2 IN MICROPHONE
//ID // Alternate Setting 0 - 0 endpoint
0x09, // Size : 9 Bytes
USB_DESCRIPTOR_INTERFACE, // Interface Descriptor (0x04)
0x02, // bInterfaceNumber -> 0x02 Interface ID = 2
0x00, // bAlternateSetting -> 0x00 = Value used to select this alternate setting for the interface identified in the prior field
0x00, // bNumEndpoints -> 0x00 = 0 -> Number of endpoints used by this interface
AUDIO_DEVICE, // bInterfaceClass -> 0x01 = 1 = AUDIO
AUDIOSTREAMING, // bInterfaceSubClass -> 0x02 = AUDIO_STREAMING
0x00, // bInterfaceProtocol -> 0x00 = Unused
0x00, // iInterface -> 0x00 = Unused -> Index of string descriptor.
//ID // Alternate Setting 1 - 1 endpoint
0x09, // Size : 9 Bytes
USB_DESCRIPTOR_INTERFACE, // Interface Descriptor (0x04)
0x02, // bInterfaceNumber -> 0x02 Interface ID = 2
0x01, // bAlternateSetting -> 0x01 = Value used to select this alternate setting for the interface identified in the prior field
0x01, // bNumEndpoints -> 0x01 = 1 -> Number of endpoints used by this interface
0x01, // bInterfaceClass -> 0x01 = 1 = AUDIO
0x02, // bInterfaceSubClass -> 0x02 = AUDIO_STREAMING
0x00, // bInterfaceProtocol -> 0x00 = Unused
0x00, // iInterface -> 0x00 = Unused -> Index of string descriptor.
// ASID GENERAL
0x07, // Size : 7 Bytes
CS_INTERFACE, // CS_INTERFACE Descriptor Type
AS_GENERAL, // GENERAL Descriptor
0x06, // bTerminalLink -> 0x06 = The Terminal ID of the Terminal to which the endpoint of this interface is connected. = 6
0x01, // bDelay -> 0x01 = Delay (delta) introduced by the data path (see Section 3.4, ?Inter Channel Synchronization? - in Audio Devices). Expressed in number of frames.
0x01,0x00, // wFormatTag -> 0x0001 = PCM
// ASID FORMAT_TYPE
0x0E, // Size : 14 Bytes
CS_INTERFACE, // CS_INTERFACE Descriptor Type
FORMAT_TYPE, // bDescriptorSubtype -> 0x02 = FORMAT_TYPE
0x01, // bFormatType -> 0x01 = FORMAT_TYPE_I -> ref: A.1.1 Audio Data Format Type I Codes -> Audio Data Format Dok
0x02, // bNrChannels -> 0x02 = Two channels
BYTES_PR_SAMPLE, // bSubFrameSize -> 0x03 = 3 bytes pr audio subframe
BIT_RESOLUTION, // bBitResolution -> 0x18 = 24 bit pr sample
0x02, // bSamFreqType -> 0x02 = 2 sample frequencies supported
0x00,0x7D,0x00, // tSamFreq -> 0x7D00 = 32000 Hz
0x80,0xBB,0x00, // tSamFreq -> 0xBB80 = 48000 Hz
//ED ENDPOINT IN
0x09, // Size : 9 Bytes
USB_DESCRIPTOR_ENDPOINT, // 0x05 -> ENDPOINT Descriptor Type
0x82, // bEndpointAddress -> 0x82 = adress 2, IN, -> ref 9.6.6 Endpoint -> usb_20 Dok
0x05, // bmAttributes -> 0b00000101 -> Bits 0-1 = 01 = Isochronous , Bits 2-3 = 01 = Asynchronous
AUDIO_MAX_SAMPLES * sizeof ( AUDIO_PLAY_SAMPLE ), AUDIO_MAX_SAMPLES * sizeof ( AUDIO_PLAY_SAMPLE )>>8,
0x01, // bInterval -> 0x01 = 1 millisecond
0x00, // unused
0x00, // unused
//AS ENDPOINT
0x07, // Size : 7 Bytes
CS_ENDPOINT, // bDescriptorType -> 0x25 = CS_ENDPOINT
EP_GENERAL, // bDescriptorSubtype -> 0x01 = GENERAL
SAMPLING_FREQ_CONTROL, // bmAttributes -> 0b00000001 = Bit 1 = 1 => Sample Freq Control is supported by this endpoint
0x00, // bLockDelayUnits -> 0x00 = Indicates the units used for the wLockDelay field: 0 = Undefined
0x00,0x00, // the time it takes this endpoint to reliably lock its internal clock recovery circuitry.
