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

[Jörg Müller]

I need to combine two HDSPe MADI FX cards to one virtual device. I
have a working driver, which is alsa-compatible. I can select each
single card in any alsa-compatible application and all channels work
flawless.
For combining the MADI FX cards to one virtual device, I created an
.asoundrc with 194 inputs for each card. When I start that virtual
device via
jackd -R -d alsa -C madifx_record_all -P madifx_playback_all

I get this error:
> creating alsa driver ...
> madifx_playback_all|madifx_record_all|1024|2|48000|0|0|nomon|swmeter|-|32bit
> jackd: pcm_multi.c:1060: snd_pcm_multi_open: Assertion `!slave_map[sidxs[i]][schannels[i]]' failed.

However, it works when I reduce the amount from 194 to 64 channels per
card. I tried to use 128 channels per card, but that fails the same
way. See my alsa-info here http://pastebin.com/4hq1B3wZ , which also
includes the .asoundrc content.

I also found this, which might be related:
https://ccrma.stanford.edu/mirrors/lalists/lad/2005/06/0202.html

To me, this looks like a bug. What do you think?

For reference, I posted the same question on
http://lists.jackaudio.org/private.cgi/jack-devel-jackaudio.org/2017-January/000741.html,
however, they recommended to ask here for help.