Linux Audio record play
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DART-MX8M Audio Record/Play
Get information on the Sound Cards
Installed devices:
root@imx8m-var-dart:~# cat /proc/asound/cards
0 [wm8904audio ]: wm8904-audio - wm8904-audio
wm8904-audio
List device names for playback:
root@imx6ul-var-dart:~# aplay -L
null
Discard all samples (playback) or generate zero samples (capture)
pulse
PulseAudio Sound Server
sysdefault:CARD=wm8904audio
wm8904-audio,
Default Audio Device
Audio Playback
Set PCM volume (main volume of audio codec), range :0-63
# amixer set Headphone 35
Play audio:
# aplay /usr/share/sounds/alsa/Front_Center.wav
Example:
root@imx8m-var-dart:~# amixer set set Headphone 35 Simple mixer control 'Headphone',0 Capabilities: volume pswitch Playback channels: Front Left - Front Right Capture channels: Front Left - Front Right Limits: 0 - 63 Front Left: 35 [56%] [-22.00dB] Playback [on] Front Right: 35 [56%] [-22.00dB] Playback [on] root@imx8m-var-dart:~# 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
Set PCM volume (main volume of audio codec), range :0-63
# amixer set Headphone 35
Set capture input source to ADC
# amixer set 'Capture Input' ADC
Set DMIC Mux to DMIC2
# amixer set 'DMIC Mux' DMIC2
Record CD quality audio for 10 seconds into file test.wav
# arecord -f cd -d 10 test.wav
Play the recorded file
# aplay test.wav
Example:
root@imx8m-var-dart:~# amixer set set Headphone 35 Simple mixer control 'Headphone',0 Capabilities: volume pswitch Playback channels: Front Left - Front Right Capture channels: Front Left - Front Right Limits: 0 - 63 Front Left: 35 [56%] [-22.00dB] Playback [on] Front Right: 35 [56%] [-22.00dB] Playback [on] root@imx8m-var-dart:~# amixer set 'Capture Input' ADC Simple mixer control 'Capture Input',0 Capabilities: enum Items: 'ADC' 'DMIC' Item0: 'ADC' root@imx8m-var-dart:~# amixer set 'DMIC Mux' DMIC2 Simple mixer control 'DMIC Mux',0 Capabilities: enum Items: 'DMIC1' 'DMIC2' Item0: 'DMIC2' root@imx6ul-var-dart:~# arecord -f cd -d 10 test.wav Recording WAVE 'test.wav' : Signed 16 bit Little Endian, Rate 44100 Hz, Stereo root@imx6ul-var-dart:~# aplay test.wav Playing WAVE 'test.wav' : Signed 16 bit Little Endian, Rate 44100 Hz, Stereo
Audio Record and Play, DMIC
Set Headphones volume, range :0-63
# amixer set Headphone 35
Set capture input source to DMIC
# amixer set 'Capture Input' DMIC
Set DMIC Mux to DMIC1
# amixer set 'DMIC Mux' DMIC1
Record CD quality audio for 10 seconds into file test.wav
# arecord -f cd -d 10 test.wav
Play the recorded file
# aplay test.wav
Example:
root@imx8m-var-dart:~# amixer set set Headphone 35 Simple mixer control 'Headphone',0 Capabilities: volume pswitch Playback channels: Front Left - Front Right Capture channels: Front Left - Front Right Limits: 0 - 63 Front Left: 35 [56%] [-22.00dB] Playback [on] Front Right: 35 [56%] [-22.00dB] Playback [on] root@imx8m-var-dart:~# amixer set 'Capture Input' DMIC Simple mixer control 'Capture Input',0 Capabilities: enum Items: 'ADC' 'DMIC' Item0: 'DMIC' root@imx8m-var-dart:~# amixer set 'DMIC Mux' DMIC1 Simple mixer control 'DMIC Mux',0 Capabilities: enum Items: 'DMIC1' 'DMIC2' Item0: 'DMIC1' root@imx6ul-var-dart:~# arecord -f cd -d 10 test.wav Recording WAVE 'test.wav' : Signed 16 bit Little Endian, Rate 44100 Hz, Stereo root@imx6ul-var-dart:~# 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@imx8m-var-dart:~# amixer Simple mixer control 'Headphone',0 Capabilities: volume pswitch Playback channels: Front Left - Front Right Capture channels: Front Left - Front Right Limits: 0 - 63 Front Left: 35 [56%] [-22.00dB] Playback [on] Front Right: 35 [56%] [-22.00dB] Playback [on] Simple mixer control 'Headphone ZC',0 Capabilities: pswitch Playback channels: Front Left - Front Right Mono: Front Left: Playback [on] Front Right: Playback [on] Simple mixer control 'Line Output',0 Capabilities: volume pswitch Playback channels: Front Left - Front Right Capture channels: Front Left - Front Right Limits: 0 - 63 Front Left: 57 [90%] [0.00dB] Playback [on] Front Right: 57 [90%] [0.00dB] Playback [on] Simple mixer control 'Line Output ZC',0 Capabilities: pswitch Playback channels: Front Left - Front Right Mono: Front Left: Playback [on] Front Right: Playback [on] Simple mixer control 'Capture',0 Capabilities: cvolume cswitch Capture channels: Front Left - Front Right Limits: Capture 0 - 31 Front Left: Capture 24 [77%] [on] Front Right: Capture 24 [77%] [on] Simple mixer control 'Capture Input',0 Capabilities: enum Items: 'ADC' 'DMIC' Item0: 'DMIC' ...
Options:
amixer sset sID P set contents for one mixer simple control amixer sget sID get contents for one mixer simple control
For example:
root@imx8m-var-dart:~# amixer sget 'Capture' Simple mixer control 'Capture',0 Capabilities: cvolume cswitch Capture channels: Front Left - Front Right Limits: Capture 0 - 31 Front Left: Capture 24 [77%] [on] Front Right: Capture 24 [77%] [on] root@imx8m-var-dart:~# amixer sset 'Capture' 25 Simple mixer control 'Capture',0 Capabilities: cvolume cswitch Capture channels: Front Left - Front Right Limits: Capture 0 - 31 Front Left: Capture 25 [81%] [on] Front Right: Capture 25 [81%] [on]
Capture currently now set to 81%.
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