FAQ about audio

Why is there no sound when playing an audio file?

A: The sound controlling devices are muted by default. You need to unmute them explicitly.

Using alsamixer graphical ncurses interface

Adjust sound output using the audio mixer with the alsamixer command:

  • for AT73 DAC (at91sam9260ek, at91sam9xeek & at91sam9261ek boards)
    • Master to control volume (un-mute)
    • PCM to control digital source volume (un-mute)
  • for WM8731 DAC (at91sam9g20ek board)
    • Master to control volume (un-mute)
    • toggle Output Mixer HiFi Playback Switch to ON (un-mute)
  • for AC97 (at91sam9263ek & at91sam9rlek boards)
    • Headphone to control headphone volume (un-mute)
    • Headphone Jack Sense to Off (mute)
    • toggle Line Jack Sense to switch headphone on/off
    • Master Mono controls volume on board soldered speaker (if present) (un-mute)

Exit alsamixer with the Escape key (eventually reset the terminal with the reset command).

Using amixer command line interface

  • for AT91SAM9260EK, AT91SAM9261EK and AT91SAM9G10EK which use AT73 DAC: 
amixer set 'Master' 70 unmute
amixer set 'PCM' 70 unmute

  • For AT91SAM9G20EK which uses WM8731 DAC: 
amixer set 'Master' 70 unmute
amixer set 'Output Mixer HiFi Playback Swit' unmute

  • For AT91SAM9263EK and AT91SAM9RLEK which use AC97: 
amixer set 'Master' 70 unmute
amixer set 'PCM' 70 unmute
amixer set 'Master Mono' 70 unmute 
amixer set 'Headphone' 70 unmute

Save configuration with alsactl

You can store this sound configuration using the alsactl store command (as long as your filesystem is read/write capable).

After a reboot you can retrieve this configuration running alsactl restore.

Why is there no sound when recording an audio file?

A: As for playing sound, ALSA Linux audio subsystem keeps the devices muted by default. You need to unmute them explicitly.

Using alsamixer graphical ncurses interface

For instance the line-in and mic-in are muted by default. The user must run alsamixer and go to the capture options (F4) screen. There, the user must press the space bar on the Capture option to unmute those channels.

Why mplayer does not change volume?

A: On some platforms the volume control name is not the one expected by default by mplayer. You should change it to the one understood by the alsa control in charge of the main hardware volume control of the mixer interface. 

mplayer -ao alsa -mixer-channel Master MUSIC.mp3

Other helpful references

For details regarding how to connect the I2S controller (found on SAMA5D2 and SAM9X60) to a codec, please see I2S Multi Channel.

For details regarding the usage of PDMIC (found on SAMA5D2), please see PDMIC .