Distorted sound with external usb-device and bitperfect

[Hans Petter Selasky]

On 3/29/21 6:59 AM, Softwafe Engineer wrote:
> Here is dmesg after motu m2 was plugged:
> 
> https://pastebin.com/1mcQNn1H
> 
> (is pastebin ok?)
> 
> I've tried it in few music players which are could be find in ports
> - deadbeef
> - audacious
> 
> Both sound distorted when I enable bitperfect and disable vchans. If
> not then sounds ok.
> 
> I never try virtual_oss. I just would to send bitperfect sound from
> freebsd to motu m2 to listen music.
> 

Hi,

I suspect the applications you are trying to use don't support 32-bit 
mode via OSS. That's why you hear noise. They've configured something 
else, like 16-bit or 24-bit mode.

You could ktrace the application possibly to figure this out. It will 
show all IOCTL's.

Try to configure virtual_oss in bitperfect mode instead for a test.

Beware that many applications that output 16-bit audio, don't properly 
fill the lower bytes with noise when they resampling to 32-bit. That's 
another reason to use virtual_oss :-)

--HPS