Unable to record audio using microphone imx8mplus

[PoojaSk]

Hi, 
 I have tried connecting headset and recording audio using microphone in imx8MPlus flashe d with LinuxBSP but  audio is not captured. Is there some other settings to be done if so please share the steps or documentation for the same.

Thanks,
Pooja

[Bio_TICFSL · Accepted solution]

Hello,

You have to use the latest BSP, then get information on the sound cards

Installed devices:

# cat /proc/asound/cards
 0 [wm8904audio      ]: wm8904-audio - wm8904-audio
                      wm8904-audio

List device names for playback:

# 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

PulseAudio needs to be stopped to run amixer commands.

# systemctl stop pulseaudio

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:

# systemctl stop pulseaudio;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]

# 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

PulseAudio needs to be stopped to run amixer commands.

# systemctl stop pulseaudio

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:

# systemctl stop pulseaudio; 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]
# amixer set 'Capture Input' ADC                                                                                                                                                         
Simple mixer control 'Capture Input',0
  Capabilities: enum
  Items: 'ADC' 'DMIC'
  Item0: 'ADC'
# amixer set 'DMIC Mux' DMIC2
Simple mixer control 'DMIC Mux',0
  Capabilities: enum
  Items: 'DMIC1' 'DMIC2'
  Item0: 'DMIC2'
# arecord -f cd -d 10 test.wav
Recording WAVE 'test.wav' : Signed 16 bit Little Endian, Rate 44100 Hz, Stereo
# aplay test.wav
Playing WAVE 'test.wav' : Signed 16 bit Little Endian, Rate 44100 Hz, Stereo

Audio Record and Play, DMIC

PulseAudio needs to be stopped to run amixer commands.

# systemctl stop pulseaudio

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:

 # systemctl stop pulseaudio;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]
# amixer set 'Capture Input' DMIC                                                                                                                                                         
Simple mixer control 'Capture Input',0
  Capabilities: enum
  Items: 'ADC' 'DMIC'
  Item0: 'DMIC'
# amixer set 'DMIC Mux' DMIC1
Simple mixer control 'DMIC Mux',0
  Capabilities: enum
  Items: 'DMIC1' 'DMIC2'
  Item0: 'DMIC1'
# arecord -f cd -d 10 test.wav
Recording WAVE 'test.wav' : Signed 16 bit Little Endian, Rate 44100 Hz, Stereo
# aplay test.wav
Playing WA

the everything works on EVK

Alfredo