[alsa-devel] Attempting to understand odd snd-usb-audio code and behavior

[Clemens Ladisch]

Keith A. Milner wrote:
>>> kernel: [ 1987.452947] usb 1-1: Unable to change format on ep #8e: already in use
>
> So the error messages are due to a userspace app trying to open playback and
> capture at the same time?

For this device, playback requires a running capture stream to determine
the rate of packets.  This error happens when the application tries to
open the capture stream after the playback stream.  (If the format does
not actually need to change, the error message is misleading.)

Your actual problem is that the device does not send any capture packets.


Regards,
Clemens