Microphone Sampling Offset of Matrix Creator

Hi,

I find that the sampling of the microphone is not accurate on my matrix creator with raspberry pi 3. It samples slower than the standard sampling. How can I configure sampling intervals?

Thanks.

@sunwell,

If you’re using ALSA to record you can set the sampling rate. In the command line version, for a 5 second recording, that would be:

arecord -f S16_LE -r 44100 -d 5

Most ALSA wrappers will also have a rate setting parameter.

If you are using MATRIX HAL, there is a function to set sampling rate, see here.

Best,
Samreen

Hi Samreen,

The key problem is the sampling is not accurate. for your example, it may only receive 44000 samples in 1 second. I thinks the sample clock is not accurate.

Best

It is strange. I have been working with FPGA code and it works just fine. Do you use HAL or other enviroment?

“it may only receive 44000 samples”. Is it an example? Is number of samples the same for all microphones?

Best,
Miguel

Thanks Miguel.
My description is not accurate. I refer to it may receive 44000 samples in 1 second so it may take 1.002 seconds to receive 44100 samples.

@sunwell,

I have brought this to the attention of our hardware engineers to see if they can recommend any tests.

You can check where the sampling is specified in the kernel modules here. The code indicates the sampling should be accurate so we are investigating further.

Best,
Samreen