I am currently working on USB microphone (Samson Q1U) support for my Android app using libusb (1.0.9). I have gotten data streaming from the device working no problem, but I would like to read information about the data format (bit depth, sample rates, channels). So far, USB has been really confusing, so forgive my attempt at its usage below. The problem is the control transfer, I don't believe it is setup correctly. I have tried many different transfer parameter combinations, but all have return error codes -1, -7, & -9. Any help would be great.
Essentially, I want to get this descriptor:
AudioStreaming Interface Descriptor:
bLength 23
bDescriptorType 36
bDescriptorSubtype 2 (FORMAT_TYPE)
bFormatType 1 (FORMAT_TYPE_I)
bNrChannels 1
bSubframeSize 2
bBitResolution 16
bSamFreqType 5 Discrete
tSamFreq[ 0] 8000
tSamFreq[ 1] 11025
tSamFreq[ 2] 22050
tSamFreq[ 3] 44100
tSamFreq[ 4] 48000
This is my code for the control transfer:
extern "C" void Java_com_example_test_LibUsb_nativeGetAudioInfo(JNIEnv *env, jobject obj){
libusb_init(NULL);
devh = libusb_open_device_with_vid_pid(NULL,VID,PID);
libusb_kernel_driver_active(devh, 0);
libusb_detach_kernel_driver(devh, 0);
libusb_claim_interface(devh, 0);
libusb_set_interface_alt_setting(devh,0,0);
uint8_t requestType = 0b1 | 0b01 | 0b00001;
uint8_t bRequest = 0x06;
uint16_t wValue = 0x24;
uint16_t wIndex = 0;
unsigned char data[23];
unsigned int timeout = 1000;
int rc = libusb_control_transfer(devh, requestType, bRequest, wValue, wIndex, data, sizeof(data), timeout);
LOGD("%d",rc);
int cnt = 0;
if(rc > 0){
char bLength = data[cnt++];
char bDescriptorType = data[cnt++];
char bDescriptorSubtype = data[cnt++];
char bFormatType = data[cnt++];
char bNrChannels = data[cnt++];
char bSubframeSize = data[cnt++];
char bBitResolution = data[cnt++];
char bSamFreqType = data[cnt++];
int rates[bSamFreqType];
LOGD("%d",bNrChannels);
LOGD("%d",bBitResolution);
for(int i = 0;i < bSamFreqType;i++){
char byte1 = data[cnt++];
char byte2 = data[cnt++];
char byte3 = data[cnt++];
rates[i] = ((byte1 & 0xFF) << 8 | (byte2 & 0xFF) << 16 | (byte3 & 0xFF) << 24);
LOGD("%d",rates[i]);
}
}
libusb_exit(NULL);
}
Here is the full device descriptor:
Device Descriptor:
bLength 18
bDescriptorType 1
bcdUSB 1.10
bDeviceClass 0 (Defined at Interface level)
bDeviceSubClass 0
bDeviceProtocol 0
bMaxPacketSize0 8
idVendor 0x17a0 Samson Technologies Corp.
idProduct 0x0002 Q1U dynamic microphone
bcdDevice 0.01
iManufacturer 1
iProduct 2
iSerial 0
bNumConfigurations 1
Configuration Descriptor:
bLength 9
bDescriptorType 2
wTotalLength 177
bNumInterfaces 2
bConfigurationValue 1
iConfiguration 0
bmAttributes 0x80
(Bus Powered)
MaxPower 90mA
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 0
bAlternateSetting 0
bNumEndpoints 0
bInterfaceClass 1 Audio
bInterfaceSubClass 1 Control Device
bInterfaceProtocol 0
iInterface 0
AudioControl Interface Descriptor:
bLength 9
bDescriptorType 36
bDescriptorSubtype 1 (HEADER)
bcdADC 1.00
wTotalLength 40
bInCollection 1
baInterfaceNr( 0) 1
AudioControl Interface Descriptor:
bLength 12
bDescriptorType 36
bDescriptorSubtype 2 (INPUT_TERMINAL)
bTerminalID 1
wTerminalType 0x0201 Microphone
bAssocTerminal 2
bNrChannels 2
wChannelConfig 0x0003
Left Front (L)
Right Front (R)
iChannelNames 0
iTerminal 0
AudioControl Interface Descriptor:
bLength 9
bDescriptorType 36
bDescriptorSubtype 3 (OUTPUT_TERMINAL)
bTerminalID 2
wTerminalType 0x0101 USB Streaming
bAssocTerminal 1
bSourceID 3
iTerminal 0
AudioControl Interface Descriptor:
bLength 10
bDescriptorType 36
bDescriptorSubtype 6 (FEATURE_UNIT)
bUnitID 3
bSourceID 1
bControlSize 1
bmaControls( 0) 0x01
Mute Control
bmaControls( 1) 0x02
Volume Control
bmaControls( 2) 0x02
Volume Control
iFeature 0
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 1
bAlternateSetting 0
bNumEndpoints 0
bInterfaceClass 1 Audio
bInterfaceSubClass 2 Streaming
bInterfaceProtocol 0
iInterface 0
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 1
bAlternateSetting 1
bNumEndpoints 1
bInterfaceClass 1 Audio
bInterfaceSubClass 2 Streaming
bInterfaceProtocol 0
iInterface 0
AudioStreaming Interface Descriptor:
bLength 7
bDescriptorType 36
bDescriptorSubtype 1 (AS_GENERAL)
bTerminalLink 2
bDelay 1 frames
wFormatTag 1 PCM
AudioStreaming Interface Descriptor:
bLength 23
bDescriptorType 36
bDescriptorSubtype 2 (FORMAT_TYPE)
bFormatType 1 (FORMAT_TYPE_I)
bNrChannels 1
bSubframeSize 2
bBitResolution 16
bSamFreqType 5 Discrete
tSamFreq[ 0] 8000
tSamFreq[ 1] 11025
tSamFreq[ 2] 22050
tSamFreq[ 3] 44100
tSamFreq[ 4] 48000
Endpoint Descriptor:
bLength 9
bDescriptorType 5
bEndpointAddress 0x81 EP 1 IN
bmAttributes 5
Transfer Type Isochronous
Synch Type Asynchronous
Usage Type Data
wMaxPacketSize 0x0064 1x 100 bytes
bInterval 1
bRefresh 0
bSynchAddress 0
AudioControl Endpoint Descriptor:
bLength 7
bDescriptorType 37
bDescriptorSubtype 1 (EP_GENERAL)
bmAttributes 0x01
Sampling Frequency
bLockDelayUnits 0 Undefined
wLockDelay 0 Undefined
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 1
bAlternateSetting 2
bNumEndpoints 1
bInterfaceClass 1 Audio
bInterfaceSubClass 2 Streaming
bInterfaceProtocol 0
iInterface 0
AudioStreaming Interface Descriptor:
bLength 7
bDescriptorType 36
bDescriptorSubtype 1 (AS_GENERAL)
bTerminalLink 2
bDelay 1 frames
wFormatTag 1 PCM
AudioStreaming Interface Descriptor:
bLength 23
bDescriptorType 36
bDescriptorSubtype 2 (FORMAT_TYPE)
bFormatType 1 (FORMAT_TYPE_I)
bNrChannels 2
bSubframeSize 2
bBitResolution 16
bSamFreqType 5 Discrete
tSamFreq[ 0] 8000
tSamFreq[ 1] 11025
tSamFreq[ 2] 22050
tSamFreq[ 3] 44100
tSamFreq[ 4] 48000
Endpoint Descriptor:
bLength 9
bDescriptorType 5
bEndpointAddress 0x81 EP 1 IN
bmAttributes 5
Transfer Type Isochronous
Synch Type Asynchronous
Usage Type Data
wMaxPacketSize 0x00c8 1x 200 bytes
bInterval 1
bRefresh 0
bSynchAddress 0
AudioControl Endpoint Descriptor:
bLength 7
bDescriptorType 37
bDescriptorSubtype 1 (EP_GENERAL)
bmAttributes 0x01
Sampling Frequency
bLockDelayUnits 0 Undefined
wLockDelay 0 Undefined