arif setiawan wrote:

We have a beagleboard with one audio line-in and one audio line-out. From the documentation both are stereo line. Now we want to use four mono audio line for our system. two input from radio and microphone, two output to radio and speaker. We use ALSA and we would like to know how we can achieve this either by plugin or programming alsa.

Try something like this: pcm_slave.stereo { pcm "hw:0,0" # or whatever your device is channels 2 } pcm.left { type asym playback.pcm { type plug slave.pcm { type dshare slave stereo ipc_key 200907241 bindings [ 0 ] } } capture.pcm { type plug slave.pcm { type dsnoop slave stereo ipc_key 200907242 bindings [ 0 ] } } } pcm.right { type asym playback.pcm { type plug slave.pcm { type dshare slave stereo ipc_key 20090724 bindings [ 1 ] } } capture.pcm { type plug slave.pcm { type dsnoop slave stereo ipc_key 200907242 bindings [ 1 ] } } } HTH Clemens