2011/2/7 Vincent Meserette vmeserette@aldebaran-robotics.com

To record four channels simultaneously, I have created the following alsa configuration file :

*# output device pcm.AD1989A{ type hw card 0 }

# input device* * pcm.quad { type multi

    slaves.a.pcm "hw:0,0,0" # ADC 0 of the codec (left and right mics)
    slaves.a.channels 2
    slaves.b.pcm "hw:0,0,1" # ADC 1 of the codec (front and rear mics)
    slaves.b.channels 2

    bindings.0.slave a
    bindings.0.channel 0
    bindings.1.slave a
    bindings.1.channel 1
    bindings.2.slave b
    bindings.2.channel 0
    bindings.3.slave b
    bindings.3.channel 1

}

# input device containing interleaved data pcm.quad2 { type route slave.pcm "quad" ttable.0.0 1 ttable.1.1 1 ttable.2.2 1 ttable.3.3 1 }

### CTL DEVICES (controls) ctl.mixer0 { type hw card 0 }*

With this configuration file, I am able to record the four channels simultaneously with the following command :

arecord -c4 -fS16_LE -r48000 -D «quad2 » -d5 /tmp/recording.wav

it is strange that I alway got overrun only at the first time of running the above command but no overrun on the second time

arecord -v -c4 -fS16_LE -r48000 -D quad2 -d5 /tmp/recording.wav Recording WAVE '/tmp/recording.wav' : Signed 16 bit Little Endian, Rate 48000 Hz, Channels 4 Route conversion PCM Transformation table: 0 <- 0 1 <- 1 2 <- 2 3 <- 3 Its setup is: stream : CAPTURE access : RW_INTERLEAVED format : S16_LE subformat : STD channels : 4 rate : 48000 exact rate : 48000 (48000/1) msbits : 16 buffer_size : 16384 period_size : 4096 period_time : 85333 tstamp_mode : NONE period_step : 1 avail_min : 4096 period_event : 0 start_threshold : 1 stop_threshold : 16384 silence_threshold: 0 silence_size : 0 boundary : 1073741824 Slave: Multi PCM Channel bindings: 0: slave 0, channel 0 1: slave 0, channel 1 2: slave 1, channel 0 3: slave 1, channel 1 Its setup is: stream : CAPTURE access : MMAP_COMPLEX format : S16_LE subformat : STD channels : 4 rate : 48000 exact rate : 48000 (48000/1) msbits : 16 buffer_size : 16384 period_size : 4096 period_time : 85333 tstamp_mode : NONE period_step : 1 avail_min : 4096 period_event : 0 start_threshold : 1 stop_threshold : 16384 silence_threshold: 0 silence_size : 0 boundary : 1073741824 Slave #0: Hardware PCM card 1 'HDA Intel' device 0 subdevice 0 Its setup is: stream : CAPTURE access : MMAP_INTERLEAVED format : S16_LE subformat : STD channels : 2 rate : 48000 exact rate : 48000 (48000/1) msbits : 16 buffer_size : 16384 period_size : 4096 period_time : 85333 tstamp_mode : NONE period_step : 1 avail_min : 4096 period_event : 0 start_threshold : 1 stop_threshold : 16384 silence_threshold: 0 silence_size : 0 boundary : 1073741824 appl_ptr : 0 hw_ptr : 0 Slave #1: Hardware PCM card 1 'HDA Intel' device 0 subdevice 1 Its setup is: stream : CAPTURE access : MMAP_INTERLEAVED format : S16_LE subformat : STD channels : 2 rate : 48000 exact rate : 48000 (48000/1) msbits : 16 buffer_size : 16384 period_size : 4096 period_time : 85333 tstamp_mode : NONE period_step : 1 avail_min : 4096 period_event : 0 start_threshold : 1 stop_threshold : 16384 silence_threshold: 0 silence_size : 0 boundary : 1073741824 appl_ptr : 0 hw_ptr : 0 overrun!!! (at least 0.001 ms long) Status: state : XRUN trigger_time: 1077.282286934 tstamp : 1077.282292637 delay : 0 avail : 16384 avail_max : 16384 overrun!!! (at least 0.001 ms long) Status: state : XRUN trigger_time: 1077.623810402 tstamp : 1077.623819150 delay : 0 avail : 16384