[pulseaudio-discuss] Another take on profiles for multichannel devices

David Henningsson david.henningsson at canonical.com
Tue Mar 4 06:34:25 PST 2014

The recent question about ufx1604 had me thinking if there is an easier
way to deal with multichannel devices for all devices, not only firewire.

And here's the idea:

Let's add another key to profile-sets, let's call it
"allow-extra-channels" or something. If that key is set, we're allowed
to use more channels than specified in the channel map.

The extra channels gets filled up with aux0, aux1 and so on. (Possibly
skipping over aux channels already in the map.)

For our alsa-lib interface, this means that if the key is set, we'll
call snd_pcm_hw_params_set_channels_min and
snd_pcm_hw_params_set_channels_near instead of

In default.conf, we would then set this key only on the one that already
exposes maximum number of channels, which in practice means
analog-surround-71 for output and analog-4-channel-input for input.

Does this make sense?

David Henningsson, Canonical Ltd.

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