[pulseaudio-tickets] [PulseAudio] #624: need proper support for Terratec EWS88-MT (ice1712)

[PulseAudio]

#624: need proper support for Terratec EWS88-MT (ice1712)
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  Reporter:  aelschuring  |       Owner:  lennart          
      Type:  defect       |      Status:  new              
 Milestone:               |   Component:  module-alsa-*    
Resolution:               |    Keywords:  ews88 profile-set
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Comment(by timj):

 I have an M-Audio Audiophile 24/96 (2 physical analogue inputs, 2 physical
 analogue outputs, 1 physical SPDIF in, 1 physical SPDIF out, but with 8
 PCM channels) and I have to say that the above patch "pulseaudio-add-
 profile-sets-for-M_Audio-Audiophile-2496.patch" works perfectly for me
 (tested: analogue in/out, SPDIF out). Lennart, I understand your point in
 comment #23 re exposing "null" channels on the UI, but:

 a) I'm not sure that exposing those channels is actually wrong. As far as
 I can tell, although they are not useful for a typical configuration,
 those channels are not useless (as I'll try to explain in a while)

 b) even if it is, it sounds like this can't be resolved until the point in
 comment #29 (decoupling volume and PCM channel maps) is fixed. So would it
 be worth considering adding the profile set patch in the meantime?

 These cards are certainly weird, but AFAICT the logic of having more PCM's
 than there are physical outputs is because the card is more like a mixing
 desk than a sound card: it can internally mix/patch multiple PCMs and acts
 as a layer of control which completely decouples both:

 - the PCM channels from the digital mixer (N.B. digital mixer levels are
 also completely separate from the ADC/DAC volume controls)

 - the physical inputs/outputs from anything else (via a patchbay) - you
 can assign each physical analogue/digital output to come from: PCM
 channels 1/2, digital mix L/R, or any of the physical inputs.  (The
 patches seem to be exposed by ALSA as options called "H/W" and "H/W 1" for
 analogue out and "S/PDIF", "S/PDIF 1" for SPDIF out). By default, the
 analogue outputs (at least on my card) are usually set to PCM channels 1/2
 (i.e. completely bypassing the card's internal multi-PCM digital mixer,
 and making it more like a "normal" 2-channel sound card where PCM1/2 are
 attached to physical L/R outputs - this seems like a sensible default).

 It's a bit hard to explain, but the easiest way of controlling these is
 via "envy24control" (part of alsa-tools):
 http://images.google.co.uk/images?q=envy24control is probably the best way
 to see it. And I'm just about to attach an image of my envy24control
 patchbay (N.B. setting the S/PDIF output to "S/PDIF Out (L)" seems to do
 the same as setting the analogue output to "PCM Out 1", "S/PDIF Out (R)"
 == "PCM Out 2"). If I can post any more helpful screenshots let me know.

 As far as I can tell (this is mostly from experimenting with
 envy24control), there is nothing actually special about PCM1/2 AFAICT,
 *except* that unlike the rest, you can patch the physical outputs to come
 directly from them as per the default configuration. (You can't patch the
 outputs to connect directly to e.g. PCM3/4, which seems to me to be an
 anomaly if the card is trying to emulate a "real" mixing desk, unless
 these PCM's really are "dead" and useless).

 From my point of view as an owner of one of these cards, I accept that
 they work on a very different model to most cards and the only thing I
 really want PA to do is make sound go to (at least) PCM1/2 by default,
 which is what the modified mixer profile does. Exposing the other PCM's is
 not necessary for my personal scenario but probably actually a *good*
 thing in general for more esoteric configurations, assuming that PCM3..8
 really do work. The only anomaly is that when using the patch above and
 all the "aux" channels are turned up (where aux0/1 = the card's PCM3/4),
 no sound seems to be actually sent to any PCM other than PCM1/2 (at least,
 the monitors in envy24control don't show anything, and patching the output
 to digital mix and unmuting PCM3/4..8 doesn't do anything). Unless (again)
 these PCM's really are dud.
 Technically speaking, it's also not quite right to call PCM1/2 "front
 left" and "front right", because if you switch the physical outputs to
 come from the digital mix then it seems like PCM1/2 are just like any
 other channel, and what actually goes to physical L/R output depends on
 how the channels are mixed.

 The caveat with all the above is that actually all I use the card for is
 to provide straightforward 2-channel stereo output to analogue/SPDIF, so I
 haven't actually tried sending audio to the other PCMs. I'm not entirely
 clear how to test this - is there a magic ALSA device string? (I tried
 "aplay hw:3,1 ... " - my card is #3, but that didn't work)

-- 
Ticket URL: <http://pulseaudio.org/ticket/624#comment:31>
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