On Wed, Sep 29, 2021 at 05:23:37PM +0200, Sebastian Roth wrote:
In our lab, we have a Fireface 802 sound card from
RME. But RME doesn't
offer support in Linux and unfortunately doesn't provide drivers.
FYI there is some support for certain RME Firewire-capable interfaces when
connected to a firewire bus: FFADO supports the Fireface 400 and 800 and
there is varied support in ALSA for the 400, 800, UCX, 802 and UFX (the
latter is marked as untested). However, I am not aware of any work being
done on the proprietary USB connectivity to RME devices.
I run the Fireface in ClassCompliant mode and it is
connected via USB to
the computer with Ubuntu Studio 20.04 LTS as operating system. Basically
the Fireface works, I can use 8 output channels for my sound playback via
Jack. But the problem is that I actually want to get playback from 12
loudspeakers in our loudspeaker circuit. When I start Jack, it displays
22 output channels, but as I said, only 8 playback channels are playing
I recall reading somewhere that the RME devices only provide access to the
first 8 channels when running in USB class compliant mode. I think it was
buried in a manual, but I don't remember which model it might have been for.
It was probably the Fireface 800.
With this in mind it is not all that surprising that you can only use the
first 8 channels. What I am somewhat puzzled about is that jackd is
reporting the presence of 22 channels. Perhaps the device tells the USB
class driver that it has 22 channels but only passes audio to 8.
Could this be caused by the snd_usb_audio driver?
It is most likely a limitation of the Fireface 802. However, if you do
discover a workaround I'm sure there are many people who would be very happy
to know about it. :-)