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[ALSA/PulseAudio] Can't capture audio

Question asked by Koenraad Verheyden on Apr 19, 2017
Latest reply on May 3, 2017 by igorpadykov

Hey all,

 

I am using the Pico-i.MX6UL using Yocto (fsl-community-bsp). I can't capture audio from the codec (sgtl5000).

The soundcard is detected fine and I can playback sound. But when I record audio (using arecord) I get silence.

 

The capture device is recognized:

$ arecord -l
**** List of CAPTURE Hardware Devices ****
card 0: sgtl5000audio [sgtl5000-audio], device 0: HiFi sgtl5000-0 []
    Subdevices: 1/1
    Subdevice #0: subdevice #0

The relevant controls in amixer:

$ amixer
Simple mixer control 'Mic',0
    Capabilities: volume volume-joined
    Playback channels: Mono
    Capture channels: Mono
    Limits: 0 - 3
    Mono: 3 [100%] [40.00dB]
Simple mixer control 'Capture',0
    Capabilities: cvolume
    Capture channels: Front Left - Front Right
    Limits: Capture 0 - 15
    Front Left: Capture 15 [100%]
    Front Right: Capture 15 [100%]
Simple mixer control 'Capture Attenuate Switch (-6dB)',0
    Capabilities: pswitch pswitch-joined
    Playback channels: Mono
    Mono: Playback [on]
Simple mixer control 'Capture Mux',0
    Capabilities: enum
    Items: 'MIC_IN' 'LINE_IN'
    Item0: 'MIC_IN'
Simple mixer control 'Capture ZC',0
    Capabilities: pswitch pswitch-joined
    Playback channels: Mono
    Mono: Playback [on]

What seems off here is that control 'Mic' does not have an on / off switch.

 

Similarly in alsamixer I can't select any channel as capture device.

Alsamixer: can't select capture.

 

Does anyone have experience with this? I can't find any information about this online.

It seems the sound card does not support audio capturing?

 

All the best,

Koenraad

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