Audio Record/Play¶
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
Audio Playback¶
Set PCM volume (main volume of audio codec), range :0-127
Play audio:
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
Audio Record and Play, Line-in Jack¶
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
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%.
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: