#619: Autodetection always shows one device per sound card but sometimes could
have more tha one
  Reporter:  howl         |       Owner:  lennart          
      Type:  enhancement  |      Status:  reopened         
 Milestone:               |   Component:  module-hal-detect
Resolution:               |    Keywords:                   

Comment(by lennart):

 First, I doubt that driving SPDIF and analog out at the same time is
 really a much needed feature. I mean, really, how many ears do you have?
 4? I am pretty sure some people do want to make sure of that, but I doubt
 it's a non-trivial number.

 Now, the big problem here is that we cannot auto detect whether spdif and
 analog are exclsuive to each other or not. Currently we try every
 combinatin of input and output and if it works add it to our list of
 working profiles. However, if we change this logic to also test every
 combination of analog out and spdif out then we have a problem: we cannot
 distuingish the case where the card supports hw mixing but only one output
 at a time and where the card supports two simultaneous and independant
 outputs. That means on some hardware we'd expose a profile "spdif out +
 analog out" which would actuallly mix and output to one, or to both
 outputs. And we certainly don't want to expose that.

 So, as mentioned, the alsa enumeration API is just too simple. It does not
 include information about which devices of a card can be used together and
 which devices cannot.

Ticket URL: <http://pulseaudio.org/ticket/619#comment:14>
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