Hi Daniel and Alsa folks,
At present I am involved with resolving some issues that have arisen from people using the Audio 4DJ interface with Portaudio, and I hoped it would be OK to check a few Alsa details with you? Unfortunately I have limited experience of USB audio.
Apparently the 4 audio inputs/outputs appear as 2 stereo sub-devices on the first device, rather than a single 4-channel device - is this correct?
Assuming that is correct, does that arise as a result of the intrinsic nature of the interface, or is it by developer choice in the driver (for example so that it can be opened as 2 stereo streams)? Is there (or could there be) a way to change this, eg by module option or udev rule? I notice in the source #define CHANNELS_PER_STREAM 2
Is there a way at present that the device can be accessed as a single 4-channel stream other than by creating a custom ~asoundrc with a pcm definition using 'multi' to join the 2 stereo streams?
I don't see any USB audio units having files in /usr/share/alsa/cards; is it not relevant, not normally necessary or something no-one has got round to writing?
I appreciate any clarification you can bring.
Regards
Alan