OPI Zero: Microphone Samplerate set to 24kHz (?)

[DH1TW]

Hi,

 

I'm running Armbian 5.38 with kernel 3.4.113-sun8i on an Orange Pi Zero.

 

I'm writing an audio streaming application using the portaudio library for accessing the soundcard.

It seems that the OPI Zero samplerate for the built-in microphone is configured at 24kHz instead of 48kHz.

 

$ cat /proc/asound/card0/pcm0c/sub0/hw_params

access: MMAP_INTERLEAVED
format: S16_LE
subformat: STD
channels: 1
rate: 24000 (24000/1)
period_size: 960
buffer_size: 1920

 

If I connect an external USB soundcard, I get the expected values:

$ cat /proc/asound/card2/pcm0c/sub0/hw_params

access: RW_INTERLEAVED
format: S16_LE
subformat: STD
channels: 1
rate: 48000 (48000/1)
period_size: 6000
buffer_size: 24000

 

I think the microphone input of the OPI Zero's builtin audio codec should also be 48kHz, shouldn't it?

 

The way it currently works causes problems with portaudio.

 

Tobias