Hello, I just got an RME Babyface Pro USB sound card. It can operate either as a USB audio class compliant device (with mixing controlled by the device's physical controls) or make use of a proprietary driver on Windows and Mac OS X. The proprietary driver allows for control of the mixing capabilities of the device and using onboard DSP EQ. It would be great if someone wrote a Linux driver to make use of these. I'd be happy to send debugging info or whatever about the device and test kernel patches. I could set up a Windows VM to intercept USB communication.
In the meantime, I am trying to use its class compliant mode to use with Mixxx for DJing. However, I cannot figure out how to use channels 3-4 for my headphones. The device has 4 analog channels out and in plus 8 digital out and in (via ADAT). Its manual says, regarding class compliant mode, "in Mac OS X, either the first two or all channels will work, depending on the choice in the Audio MIDI Setup." I believe the two channel operation exists so when the Babyface Pro is plugged into an iPad, the iPad sends stereo output from iTunes and other programs to the Babyface Pro's main output. However, I do not know how to select between this 2 channel mode and the 12 channel mode with Linux. PulseAudio only shows it as a stereo device. Mixxx, which uses the PortAudio library, displays all 12 channels as available but doesn't work when any channels other than 1-2 are selected. Here is debugging output of Mixxx:
Debug [Main]: SoundManager::setupDevices() Debug [Main]: SoundDevicePortAudio::open() "2, Babyface Pro (70785713): USB Audio (hw:1,0)" Debug [Main]: framesPerBuffer: 256 Debug [Main]: Requested sample rate: 44100 Hz, latency: 5.80499 ms Debug [Main]: Output channels: 4 | Input channels: 0 Debug [Main]: Opening stream with id 2 Expression 'alsa_snd_pcm_hw_params_set_channels( pcm, hwParams, self->numHostChannels )' failed in 'src/hostapi/alsa/pa_linux_alsa.c', line: 2051 Expression 'PaAlsaStreamComponent_InitialConfigure( &self->playback, outParams, self->primeBuffers, hwParamsPlayback, &realSr )' failed in 'src/hostapi/alsa/pa_linux_alsa.c', line: 2717 Expression 'PaAlsaStream_Configure( stream, inputParameters, outputParameters, sampleRate, framesPerBuffer, &inputLatency, &outputLatency, &hostBufferSizeMode )' failed in 'src/hostapi/alsa/pa_linux_alsa.c', line: 2838 Warning [Main]: Error opening stream: Invalid number of channels
aplay -l output: **** List of PLAYBACK Hardware Devices **** card 0: PCH [HDA Intel PCH], device 0: ALC272 Analog [ALC272 Analog] Subdevices: 1/1 Subdevice #0: subdevice #0 card 0: PCH [HDA Intel PCH], device 3: HDMI 0 [HDMI 0] Subdevices: 1/1 Subdevice #0: subdevice #0 card 1: Pro70785713 [Babyface Pro (70785713)], device 0: USB Audio [USB Audio] Subdevices: 1/1 Subdevice #0: subdevice #0
aplay -L output: null Discard all samples (playback) or generate zero samples (capture) pulse PulseAudio Sound Server default Default ALSA Output (currently PulseAudio Sound Server) sysdefault:CARD=PCH HDA Intel PCH, ALC272 Analog Default Audio Device front:CARD=PCH,DEV=0 HDA Intel PCH, ALC272 Analog Front speakers surround21:CARD=PCH,DEV=0 HDA Intel PCH, ALC272 Analog 2.1 Surround output to Front and Subwoofer speakers surround40:CARD=PCH,DEV=0 HDA Intel PCH, ALC272 Analog 4.0 Surround output to Front and Rear speakers surround41:CARD=PCH,DEV=0 HDA Intel PCH, ALC272 Analog 4.1 Surround output to Front, Rear and Subwoofer speakers surround50:CARD=PCH,DEV=0 HDA Intel PCH, ALC272 Analog 5.0 Surround output to Front, Center and Rear speakers surround51:CARD=PCH,DEV=0 HDA Intel PCH, ALC272 Analog 5.1 Surround output to Front, Center, Rear and Subwoofer speakers surround71:CARD=PCH,DEV=0 HDA Intel PCH, ALC272 Analog 7.1 Surround output to Front, Center, Side, Rear and Woofer speakers hdmi:CARD=PCH,DEV=0 HDA Intel PCH, HDMI 0 HDMI Audio Output sysdefault:CARD=Pro70785713 Babyface Pro (70785713), USB Audio Default Audio Device front:CARD=Pro70785713,DEV=0 Babyface Pro (70785713), USB Audio Front speakers surround21:CARD=Pro70785713,DEV=0 Babyface Pro (70785713), USB Audio 2.1 Surround output to Front and Subwoofer speakers surround40:CARD=Pro70785713,DEV=0 Babyface Pro (70785713), USB Audio 4.0 Surround output to Front and Rear speakers surround41:CARD=Pro70785713,DEV=0 Babyface Pro (70785713), USB Audio 4.1 Surround output to Front, Rear and Subwoofer speakers surround50:CARD=Pro70785713,DEV=0 Babyface Pro (70785713), USB Audio 5.0 Surround output to Front, Center and Rear speakers surround51:CARD=Pro70785713,DEV=0 Babyface Pro (70785713), USB Audio 5.1 Surround output to Front, Center, Rear and Subwoofer speakers surround71:CARD=Pro70785713,DEV=0 Babyface Pro (70785713), USB Audio 7.1 Surround output to Front, Center, Side, Rear and Woofer speakers iec958:CARD=Pro70785713,DEV=0 Babyface Pro (70785713), USB Audio IEC958 (S/PDIF) Digital Audio Output
/proc/asound/card1/stream0 when playing to channels 1-2 with PulseAudio: RME Babyface Pro (70785713) at usb-0000:00:1d.0-1.2, high speed : USB Audio
Playback: Status: Running Interface = 1 Altset = 1 Packet Size = 47 Momentary freq = 44118 Hz (0x5.83c9) Feedback Format = 16.16 Interface 1 Altset 1 Format: S24_3LE Channels: 2 Endpoint: 3 OUT (ASYNC) Rates: 44100, 48000, 88200, 96000, 176400, 192000 Data packet interval: 125 us Interface 1 Altset 2 Format: S24_3LE Channels: 12 Endpoint: 3 OUT (ASYNC) Rates: 44100, 48000, 88200, 96000, 176400, 192000 Data packet interval: 125 us
Capture: Status: Stop Interface 2 Altset 1 Format: S24_3LE Channels: 12 Endpoint: 4 IN (ASYNC) Rates: 44100, 48000, 88200, 96000, 176400, 192000 Data packet interval: 125 us Interface 2 Altset 2 Format: S24_3LE Channels: 2 Endpoint: 4 IN (ASYNC) Rates: 44100, 48000, 88200, 96000, 176400, 192000 Data packet interval: 125 us
So I guess the question is how to get PortAudio to use the "Altset 2" option. Could this be accomplished with some asoundrc sorcery? Does something need to change in snd-usb-audio? Is the issue with PortAudio and PulseAudio? How can I test channels 3-4 with aplay or another program?