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VAR-SOM-MX6 Audio record play

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VAR-SOM-MX6 - Audio Record/Play


1 Get information on the Sound Cards

Installed devices:

root@var-som-mx6:~# cat /proc/asound/cards
 0 [tlv320aic3xaudi]: tlv320aic3x-aud - tlv320aic3x-audio
                      tlv320aic3x-audio
 1 [imxhdmisoc     ]: imx-hdmi-soc - imx-hdmi-soc
                      imx-hdmi-soc
Note: imx-hdmi-soc will be listed only if an HDMI cable is connected.

List device names for playback:

root@var-som-mx6:~# aplay -L

null
    Discard all samples (playback) or generate zero samples (capture)
sysdefault:CARD=tlv320aic3xaudi
    tlv320aic3x-audio, 
    Default Audio Device
sysdefault:CARD=imxhdmisoc
    imx-hdmi-soc, 
    Default Audio Device
surround40:CARD=imxhdmisoc,DEV=0
    imx-hdmi-soc, 
    4.0 Surround output to Front and Rear speakers
surround41:CARD=imxhdmisoc,DEV=0
    imx-hdmi-soc, 
    4.1 Surround output to Front, Rear and Subwoofer speakers
surround50:CARD=imxhdmisoc,DEV=0
    imx-hdmi-soc, 
    5.0 Surround output to Front, Center and Rear speakers
surround51:CARD=imxhdmisoc,DEV=0
    imx-hdmi-soc, 
    5.1 Surround output to Front, Center, Rear and Subwoofer speakers
surround71:CARD=imxhdmisoc,DEV=0
    imx-hdmi-soc, 
    7.1 Surround output to Front, Center, Side, Rear and Woofer speakers

2 Audio Playback

Set PCM volume (main volume of audio codec), range :0-127

$ amixer set PCM 127

Play audio:

$ aplay /usr/share/sounds/alsa/Front_Center.wav

Example:

root@var-som-mx6:~# amixer set PCM 125
Simple mixer control 'PCM',0
  Capabilities: pvolume
  Playback channels: Front Left - Front Right
  Limits: Playback 0 - 127
  Mono:
  Front Left: Playback 125 [98%] [-1.00dB]
  Front Right: Playback 125 [98%] [-1.00dB]
root@var-som-mx6:~# aplay /usr/share/sounds/alsa/Front_Center.wav
Playing WAVE '/usr/share/sounds/alsa/Front_Center.wav' : Signed 16 bit Little Endian, Rate 48000 Hz, Mono

3 Audio Record and Play, Line-in Jack

$ arecord -f cd -d 10 -D hw:0,0 test.wav
$ aplay test.wav 

Example:

root@var-som-mx6:~# arecord -f cd -d 10 -D hw:0,0 test.wav
Recording WAVE 'test.wav' : Signed 16 bit Little Endian, Rate 44100 Hz, Stereo
root@var-som-mx6:~# ^C
root@var-som-mx6:~# aplay test.wav
Playing WAVE 'test.wav' : Signed 16 bit Little Endian, Rate 44100 Hz, Stereo

4 Advanced Controls

amixer without a parameter will show all available controls. For example:

root@var-som-mx6:~# amixer
Simple mixer control 'PCM',0
  Capabilities: pvolume
  Playback channels: Front Left - Front Right
  Limits: Playback 0 - 127
  Mono:
  Front Left: Playback 125 [98%] [-1.00dB]
  Front Right: Playback 125 [98%] [-1.00dB]
Simple mixer control 'Line',0
  Capabilities: pswitch
  Playback channels: Front Left - Front Right
  Mono:
  Front Left: Playback [on]
  Front Right: Playback [on]

...

Simple mixer control 'Right PGA Mixer Mic3R',0
  Capabilities: pswitch pswitch-joined
  Playback channels: Mono
  Mono: Playback [off]

Options:

amixer   sset sID P      set contents for one mixer simple control
amixer   sget sID        get contents for one mixer simple control

For example:

$ amixer   sget 'HP DAC'
Simple mixer control 'HP DAC',0
  Capabilities: pvolume
  Playback channels: Front Left - Front Right
  Limits: Playback 0 - 118
  Mono:
  Front Left: Playback 71 [60%] [-23.50dB]
  Front Right: Playback 71 [60%] [-23.50dB]

HP DAC is a headphones DAC gain currently set to 60%. The optional values are 0-118 equal to 0%-100%.

$ amixer   sset 'HP DAC' 117 117
Simple mixer control 'HP DAC',0
  Capabilities: pvolume
  Playback channels: Front Left - Front Right
  Limits: Playback 0 - 118
  Mono:
  Front Left: Playback 117 [99%] [-0.50dB]
  Front Right: Playback 117 [99%] [-0.50dB]

Headphones DAC gain currently now set to 99%.

5 Save / restore system's audio settings

alsactl store stores all alsamixer settings into a file
alsctl Options:

  store     <card>  save current driver setup for one or each soundcards
                      to configuration file
  restore   <card>  load current driver setup for one or each soundcards
                      from configuration file

Example:

$ alsactl store -f 123.conf
$ alsactl restore -f 123.conf