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![](data:image/svg+xml, %3Csvg xmlns='http://www.w3.org/2000/svg' height='64' class='font-weight-bold' style='font: 600 30.11764705882353px "SegoeUI", Arial' width='64'%3E%3Ccircle fill='hsl(297.6, 87%, 38%)' cx='32' cy='32' r='32' /%3E%3Ctext x='50%25' y='55%25' dominant-baseline='middle' text-anchor='middle' fill='%23FFF' %3EMB%3C/text%3E%3C/svg%3E)
Hi, I'm currently developing a USB microphone-like device that is supposed to support:
fs = 48kHz
Up to 6 channels
24bit/sample
The USB framework that comes with the hardware supports USB Audio Class 1.0 at full-speed profile. I was able to make it work with 2 channels @ 16 bits/sample. However, it fails to operate for anything above that since the Windows USB driver doesn't seem to recognize the settings specified in the USB descriptor.
I've pasted the full USB description of my device below where I set bSubframeSize = 0x03 and bBitResolution = 0x18 to work on 24bit/sample. The USB device isn't working with these changes as my recording software fails to record with it. When I set those to 16 bit/sample (bSubframeSize = 0x02 and bBitResolution = 0x10) it works without issues.
I hope anybody can advise me on that.
Information for device Bose Mathers (VID=0x05A7 PID=0xBC61):
------------------------------
Connection Information:
------------------------------
Device current bus speed: FullSpeed
Device supports USB 1.1 specification
Device address: 0x0015
Current configuration value: 0x01
Number of open pipes: 3
------------------------------
Device Descriptor:
------------------------------
0x12 bLength
0x01 bDescriptorType
0x0200 bcdUSB
0x00 bDeviceClass
0x00 bDeviceSubClass
0x00 bDeviceProtocol
0x40 bMaxPacketSize0 (64 bytes)
0x05A7 idVendor
0xBC61 idProduct
0x3050 bcdDevice
0x01 iManufacturer "Bose Corporation"
0x02 iProduct "Bose Mathers"
0x03 iSerialNumber "P329980000388741007B010"
0x01 bNumConfigurations
-------------------------
Configuration Descriptor:
-------------------------
0x09 bLength
0x02 bDescriptorType
0x00A7 wTotalLength (167 bytes)
0x04 bNumInterfaces
0x01 bConfigurationValue
0x00 iConfiguration
0xC0 bmAttributes (Self-powered Device)
0x00 bMaxPower (0 mA)
Interface Descriptor:
------------------------------
0x09 bLength
0x04 bDescriptorType
0x00 bInterfaceNumber
0x00 bAlternateSetting
0x00 bNumEndPoints
0x01 bInterfaceClass (Audio Device Class)
0x01 bInterfaceSubClass (Audio Control Interface)
0x00 bInterfaceProtocol (Audio Protocol undefined)
0x00 iInterface
AC Interface Header Descriptor:
------------------------------
0x09 bLength
0x24 bDescriptorType
0x01 bDescriptorSubtype
0x0100 bcdADC
0x0028 wTotalLength (40 bytes)
0x01 bInCollection
0x01 baInterfaceNr(1)
AC Input Terminal Descriptor:
------------------------------
0x0C bLength
0x24 bDescriptorType
0x02 bDescriptorSubtype
0x07 bTerminalID
0x0201 wTerminalType (Microphone)
0x00 bAssocTerminal
0x02 bNrChannels (2 channels)
0x0003 wChannelConfig
0x00 iChannelNames
0x00 iTerminal
AC Feature Unit Descriptor:
------------------------------
0x0A bLength
0x24 bDescriptorType
0x06 bDescriptorSubtype
0x08 bUnitID
0x07 bSourceID
0x01 bControlSize
bmaControls:
0x02 Channel(0) - Volume
0x00 Channel(1)
0x00 Channel(2)
0x00 iFeature
AC Output Terminal Descriptor:
------------------------------
0x09 bLength
0x24 bDescriptorType
0x03 bDescriptorSubtype
0x09 bTerminalID
0x0101 wTerminalType (USB Streaming)
0x00 bAssocTerminal
0x08 bSourceID
0x00 iTerminal
Interface Descriptor:
------------------------------
0x09 bLength
0x04 bDescriptorType
0x01 bInterfaceNumber
0x00 bAlternateSetting
0x00 bNumEndPoints
0x01 bInterfaceClass (Audio Device Class)
0x02 bInterfaceSubClass (Audio Streaming Interface)
0x00 bInterfaceProtocol (Audio Protocol undefined)
0x00 iInterface
Interface Descriptor:
------------------------------
0x09 bLength
0x04 bDescriptorType
0x01 bInterfaceNumber
0x01 bAlternateSetting
0x01 bNumEndPoints
0x01 bInterfaceClass (Audio Device Class)
0x02 bInterfaceSubClass (Audio Streaming Interface)
0x00 bInterfaceProtocol (Audio Protocol undefined)
0x00 iInterface
AS Interface Descriptor:
------------------------------
0x07 bLength
0x24 bDescriptorType
0x01 bDescriptorSubtype
0x09 bTerminalLink
0x00 bDelay
0x0001 wFormatTag (PCM)
AS Format Type 1 Descriptor:
------------------------------
0x0B bLength
0x24 bDescriptorType
0x02 bDescriptorSubtype
0x01 bFormatType (FORMAT_TYPE_1)
0x02 bNrChannels (2 channels)
0x03 bSubframeSize
0x18 bBitResolution (24 bits per sample)
0x01 bSamFreqType (Discrete sampling frequencies)
0x00BB80 tSamFreq(1) (48000 Hz)
Endpoint Descriptor (Audio/MIDI 1.0):
------------------------------
0x09 bLength
0x05 bDescriptorType
0x81 bEndpointAddress (IN endpoint 1)
0x01 bmAttributes (Transfer: Isochronous / Synch: None / Usage: Data)
0x0120 wMaxPacketSize (1 x 288 bytes)
0x01 bInterval (1 frames)
0x00 bRefresh
0x00 bSynchAddress
AS Isochronous Data Endpoint Descriptor:
------------------------------
0x07 bLength
0x25 bDescriptorType
0x01 bDescriptorSubtype
0x00 bmAttributes
0x02 bLockDelayUnits (decoded PCM samples)
0x0000 wLockDelay
Interface Descriptor:
------------------------------
0x09 bLength
0x04 bDescriptorType
0x02 bInterfaceNumber
0x00 bAlternateSetting
0x02 bNumEndPoints
0x03 bInterfaceClass (Human Interface Device Class)
0x00 bInterfaceSubClass
0x00 bInterfaceProtocol
0x00 iInterface
HID Descriptor:
------------------------------
0x09 bLength
0x21 bDescriptorType
0x0111 bcdHID
0x99 bCountryCode
0x01 bNumDescriptors
0x22 bDescriptorType (Report descriptor)
0x007E bDescriptorLength
Endpoint Descriptor:
------------------------------
0x07 bLength
0x05 bDescriptorType
0x01 bEndpointAddress (OUT endpoint 1)
0x03 bmAttributes (Transfer: Interrupt / Synch: None / Usage: Data)
0x0040 wMaxPacketSize (1 x 64 bytes)
0x01 bInterval (1 frames)
Endpoint Descriptor:
------------------------------
0x07 bLength
0x05 bDescriptorType
0x82 bEndpointAddress (IN endpoint 2)
0x03 bmAttributes (Transfer: Interrupt / Synch: None / Usage: Data)
0x0040 wMaxPacketSize (1 x 64 bytes)
0x01 bInterval (1 frames)
Interface Descriptor:
------------------------------
0x09 bLength
0x04 bDescriptorType
0x03 bInterfaceNumber
0x00 bAlternateSetting
0x01 bNumEndPoints
0x03 bInterfaceClass (Human Interface Device Class)
0x00 bInterfaceSubClass
0x00 bInterfaceProtocol
0x00 iInterface
HID Descriptor:
------------------------------
0x09 bLength
0x21 bDescriptorType
0x0111 bcdHID
0x00 bCountryCode
0x01 bNumDescriptors
0x22 bDescriptorType (Report descriptor)
0x00B0 bDescriptorLength
Endpoint Descriptor:
------------------------------
0x07 bLength
0x05 bDescriptorType
0x83 bEndpointAddress (IN endpoint 3)
0x03 bmAttributes (Transfer: Interrupt / Synch: None / Usage: Data)
0x0040 wMaxPacketSize (1 x 64 bytes)
0x01 bInterval (1 frames)
Microsoft OS Descriptor is not available. Error code: 0x0000001F
--------------------------------
String Descriptor Table
--------------------------------
Index LANGID String
0x00 0x0000 0x0409
0x01 0x0409 "Bose Corporation"
0x02 0x0409 "Bose Mathers"
0x03 0x0409 "P329980000388741007B010"
------------------------------
Connection path for device:
USB xHCI Compliant Host Controller
Root Hub
Qualcomm USB Hub
Bose Mathers (VID=0x05A7 PID=0xBC61) Port: 1
Running on: Windows 10 or greater (Build Version 19045)
Brought to you by TDD v2.17.0, Feb 23 2021, 14:04:02
