Re: USB audio on rasberry pi 2

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On Sunday, 15 December 2024 at 14:51, mlelstv%serpens.de@localhost <mlelstv%serpens.de@localhost> wrote:

> I had some deeper look into the problem.
> 
...
> So from 1920 Bytes the driver reports only 40, and such a "short transfer"
> is seen as an error. In reality however, all 1920 Bytes are sent, that's
> why it still sounds ok unless the error messages slow down the audio
> driver too much.


That is interesting. And it explains how an ugly hack I tied works.

The DAC which has the ideal form factor for my application is a cheap one. 
An attempt to switch the output to 44.1kHz fails.

I commented out lines in src/sys/dev/usb/uaudio.c which check for USBD_NORMAL_COMPLETION and log the message. 
I know, I know, this is Very Bad. But it did make audio on this DAC play clearly:

user@host:~ % audiocfg list
0: [*] audio0 @ uaudio0: USB audio
       playback: 2ch, 48000Hz
       record:   unavailable
       (P-) slinear_le 16/16, 2ch, { 48000 }