Configure ALSA

[xiongyihui]

1. Use plug plugin to support any sample rate and any channel number.

pcm.!default {
    type plug
    slave {
        format S16_LE
        rate 48000
        channels 2
        pcm "hw:0,0"
    }
}

2. Use dmix plugin to mix multiple streams, which allows multiple applications play simultaneously.

pcm.!default {
    type plug
    slave.pcm "dm"
}

pcm.dm {
    type dmix
    ipc_key 1024
    slave {
        pcm "hw:0,0"
    }
}

3. Use dsnoop plugin to enable several applications to record from the same device simutaneously.

pcm.dsnooped {
    type dsnoop
    slave {
        pcm "hw:0,0" 
        channels 2 
    }
}

4. Use asym plugin to separate capture and playback.

pcm.!default {
    type plug
    slave.pcm {
        type asym
        playback.pcm {
            type hw
            card 1
            rate 64000
            format S16_LE
        }
        capture.pcm {
            type hw
            card 1
            rate 48000
            format S16_LE
        }
    }
}