[alsa-devel] Cannot combine audio devices with more than 64 channels

[John Rigg]

On Tue, Jan 31, 2017 at 06:18:48PM +0100, Jörg Müller wrote:
> I applied the patch to my system and it fixed the error!
> 
> However, I get the following error which seems to be caused by a code
> not being able to handle more than 256 channels:
> > wfs at wfs16:~$ jackd -R -d alsa -C madifx_record_all -P madifx_playback_all
> > jackdmp 1.9.10
> > Copyright 2001-2005 Paul Davis and others.
> > Copyright 2004-2014 Grame.
> > jackdmp comes with ABSOLUTELY NO WARRANTY
> > This is free software, and you are welcome to redistribute it
> > under certain conditions; see the file COPYING for details
> > no message buffer overruns
> > no message buffer overruns
> > no message buffer overruns
> > JACK server starting in realtime mode with priority 10
> > self-connect-mode is "Don't restrict self connect requests"
> > audio_reservation_init
> > Acquire audio card Audio0
> > creating alsa driver ... madifx_playback_all|madifx_record_all|1024|2|48000|0|0|nomon|swmeter|-|32bit
> > configuring for 48000Hz, period = 1024 frames (21.3 ms), buffer = 2 periods
> > ALSA: final selected sample format for capture: 32bit float little-endian
> > ALSA: use 8 periods for capture
> > ALSA: final selected sample format for playback: 32bit float little-endian
> > ALSA: use 8 periods for playback
> > jackd: ../linux/alsa/JackAlsaDriver.cpp:122: virtual int Jack::JackAlsaDriver::Attach(): Assertion `fCaptureChannels < 256' failed.
> > Aborted (core dumped)
> 
> What could be the problem here?

jackd only allows 256 ports maximum by default. Try using -p option
to increase it, eg. to 512:

jackd -R -p512 -d alsa....etc

BTW you don't need to specify -R on recent jackd versions as it's
realtime by default (use -r if you don't want realtime).

John