Workaround to get FiiO BTR3's USB mode work in Linux
As of Linux 4.20.5, this device won't work on 44100 sample rate, only 48000 works.
For most users, just append these lines to /etc/pulse/daemon.conf:
default-sample-rate = 192000
alternate-sample-rate = 48000
Explaination:
Nowdays most built-in sound cards support 192kHz sample rate, so we set default-sample-rate to 192000.
When any of our sound devices doesn't support 192kHz, we want it to fallback to 48kHz (supported since AC97). So we set alternate-sample-rate to 48000.
In this way, pulseaudio will only use either 192kHz or 48kHz. This solves the problem.
Configure your software to use 48000 sample rate.
# cat /proc/asound/BTR3/stream0
FiiO BTR3 at usb-0000:00:14.0-9, full speed : USB Audio
Playback:
Status: Running
Interface = 1
Altset = 1
Packet Size = 192
Momentary freq = 48000 Hz (0x30.0000)
Interface 1
Altset 1
Format: S16_LE
Channels: 2
Endpoint: 3 OUT (NONE)
Rates: 48000, 44100
# lsusb -d 0a12:1243 -v
Bus 001 Device 031: ID 0a12:1243 Cambridge Silicon Radio, Ltd
Device Descriptor:
bLength 18
bDescriptorType 1
bcdUSB 2.00
bDeviceClass 0 (Defined at Interface level)
bDeviceSubClass 0
bDeviceProtocol 0
bMaxPacketSize0 64
idVendor 0x0a12 Cambridge Silicon Radio, Ltd
idProduct 0x1243
bcdDevice 25.20
iManufacturer 0
iProduct 2 FiiO BTR3
iSerial 3 ABCDEF0123456789
bNumConfigurations 1
Configuration Descriptor:
bLength 9
bDescriptorType 2
wTotalLength 141
bNumInterfaces 3
bConfigurationValue 1
iConfiguration 0
bmAttributes 0x80
(Bus Powered)
MaxPower 500mA
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 43
bInCollection 1
baInterfaceNr( 0) 1
AudioControl Interface Descriptor:
bLength 12
bDescriptorType 36
bDescriptorSubtype 2 (INPUT_TERMINAL)
bTerminalID 1
wTerminalType 0x0101 USB Streaming
bAssocTerminal 0
bNrChannels 2
wChannelConfig 0x0003
Left Front (L)
Right Front (R)
iChannelNames 0
iTerminal 0
AudioControl Interface Descriptor:
bLength 13
bDescriptorType 36
bDescriptorSubtype 6 (FEATURE_UNIT)
bUnitID 2
bSourceID 1
bControlSize 2
bmaControls( 0) 0x01
bmaControls( 0) 0x00
Mute Control
bmaControls( 1) 0x02
bmaControls( 1) 0x00
Volume Control
bmaControls( 2) 0x02
bmaControls( 2) 0x00
Volume Control
iFeature 0
AudioControl Interface Descriptor:
bLength 9
bDescriptorType 36
bDescriptorSubtype 3 (OUTPUT_TERMINAL)
bTerminalID 3
wTerminalType 0x0301 Speaker
bAssocTerminal 0
bSourceID 2
iTerminal 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 1
bDelay 0 frames
wFormatTag 1 PCM
AudioStreaming Interface Descriptor:
bLength 14
bDescriptorType 36
bDescriptorSubtype 2 (FORMAT_TYPE)
bFormatType 1 (FORMAT_TYPE_I)
bNrChannels 2
bSubframeSize 2
bBitResolution 16
bSamFreqType 2 Discrete
tSamFreq[ 0] 48000
tSamFreq[ 1] 44100
AudioControl Endpoint Descriptor:
bLength 7
bDescriptorType 37
bDescriptorSubtype 1 (EP_GENERAL)
bmAttributes 0x81
Sampling Frequency
MaxPacketsOnly
bLockDelayUnits 2 Decoded PCM samples
wLockDelay 0 Decoded PCM samples
Endpoint Descriptor:
bLength 9
bDescriptorType 5
bEndpointAddress 0x03 EP 3 OUT
bmAttributes 1
Transfer Type Isochronous
Synch Type None
Usage Type Data
wMaxPacketSize 0x00c0 1x 192 bytes
bInterval 1
bRefresh 0
bSynchAddress 0
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 2
bAlternateSetting 0
bNumEndpoints 1
bInterfaceClass 3 Human Interface Device
bInterfaceSubClass 0 No Subclass
bInterfaceProtocol 0 None
iInterface 0
HID Device Descriptor:
bLength 9
bDescriptorType 33
bcdHID 1.11
bCountryCode 0 Not supported
bNumDescriptors 1
bDescriptorType 34 Report
wDescriptorLength 69
Report Descriptors:
** UNAVAILABLE **
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x81 EP 1 IN
bmAttributes 3
Transfer Type Interrupt
Synch Type None
Usage Type Data
wMaxPacketSize 0x0010 1x 16 bytes
bInterval 1
Device Status: 0x0000
(Bus Powered)