Adding 4 channel capture support into McASP0

Hi Pavel,

Thanks for your reply,

We refer links you suggested:

And we did changes in kernel accordingly.

But we are facing issue when we trying to capture 4 channel audio with below Aplication exapmle.

We are getting below errors:

cannot set channel count (Invalid argument)
root@dm814x-evm:/home/cvic#

Please suggest.

Thanks,
Devang

Devang,

Is it working fine with snd_pcm_hw_params_set_channels (playback_handle, hw_params, 2)?

And does it fail when snd_pcm_hw_params_set_channels (playback_handle, hw_params, 4)?

BR
Pavel

Hi Pavel,

Thanks for the support,  We have made above changes as you suggested.

Now we are able to capture audio raw file by giving number of channels 4.Now could you please suggest  how can we identify this is 4 channel audio?

Thanks,
Devang.

Devang,

You can try with aplay, playback application or audio analyzer tool

BR
Pavel

Hi Pavel,

We are able to capture 4 channel audio now in our system,

But we are facing issue with sampling rate of audio. Can you please suggest settings required to capture 4 channel audio at 48khz sample rate?

Thanks,
Devang.

Devang,

Devang panchal said:

But we are facing issue with sampling rate of audio.

Could you be more specific, what issue you are facing?

Devang panchal said:

Can you please suggest settings required to capture 4 channel audio at 48khz sample rate?

Are you able to capture 2 channels (stereo) at 48KHz sample rate successfully? Are you able to capture 4 channels (multichannel) for other sample rates (8KHz, 11.025KHz, 16KHz, 22.05KHz, 32KHz, 44.1KHz, 64KHz, 88.2KHz, 96KHz) successfully? I mean is this issue only for 48MHz sample rate?

Please also have a try with the latest linux kernel (which has some audio fixes):

BR
Pavel

Hi Pavel,

Yes, We are able to capture 2 channel audio at 48 khz.

But when we are going to capture 4 channel at 48 khz the audio is not captured properly at 48khz. means the audio raw file play correctly at 24khz sample rate.

Thanks,
Devang.

Devang,

Devang panchal said:

audio is not captured properly at 48khz

Could you be more specific, can you provide console log output?

Are you able to capture 4 channels (multichannel) for other sample rates (8KHz, 11.025KHz, 16KHz, 22.05KHz, 32KHz, 44.1KHz, 64KHz, 88.2KHz, 96KHz) successfully?

Have you tried with the latest linux kernel?

BR
Pavel

Hi Pavel,

Yes. We are able to capture 4 channel audio with different sample rates. But the audio file only play correctly at 24 khz sample rates with 4 channel with audio analyzer tool.

Thanks,
Devang.

Devang,

Devang panchal said:

But the audio file only play correctly at 24 khz sample rates with 4 channel

Can you provide more info for the 48KHz non-working case, do you have errors in the console output?

Have you tried with the latest linux kernel?

BR
Pavel

Devang,

Devang panchal said:

We are not getting any errors while capture the 4 channel audio but the issue is we are not getting actual audio at 48 khz.

Do you have any errors reported in console during playing 4 channel audio at 48KHz or you just do not hear any sound?

BR
Pavel

Devang,

Devang panchal said:

Yes, We are not getting any errors while capturing audio.

I have asked for errors when playing audio, do you have console errors when playing the audio?

Devang panchal said:

Also we can here audio at 48 khz but it is faster than original audio.

Note that sampling frequencies for playback and capture streams should be same. What is your period size? Can you try with period size of 64.

Regards,
Pavel

Hi Pavel,

Please find attached 2 channel audio captured file and 4 channel captured audio file at 48khz for your reference.

Please change the extension of the above files to .raw.

Thanks,
Devang.

The ALSA SoC Audio Driver by default supports AIC3106 audio codec and audio in stereo mode. You should modify it to support your new audio codec.

Try with the below settings:

1. Access type - RW_INTERLEAVED
2. Channels - 4
3. Format - S16_LE
4. Period size - 64

BR
Pavel