This is in the output of dmesg:

[ 8.257450] usb 1-4: parse_audio_format_rates_v2(): unable to find clock source (clock -19)

Is it related? Is it possible to discuss this on the phone with someone at XMOS?

These are the clock frequencies - the 24MHz goes to pin 58 (CLK) and the 24.576MHz goes to pin 64. Is there anything else I should check?

Thanks again for the reply I should also point out there is a frequency shift, the input sample is 1001Hz, but when frequency analysis is done on the output, it peaks at 1003Hz. I don't believe that is a problem in itself. It is an XUF209-128-TQ64. I can send you the schematic, but I cannot post it ...

Looks like the image upload didn't work. Is there another way I can send it to you?

I can't upload an audio sample to this forum, but here is a screenshot of 1001Hz with the pop at the red line.
We are using a custom board.

After more testing, I have discovered that popping noise occurs when only one stream is being played, it just takes longer to manifest itself.

Thanks for the reply. Any suggestions on how to go about debugging the ALSA layer?

Thanks,
Jim

Hi,

I'm working with a board that has a XUF208-128-TQ64 and is connected to a Linux machine by USB. When playing one stream it works well, but when two streams are sent, there is a popping noise with an approximate 2 second interval.

Any suggestions?

Thanks, Jim.