[LAU] Jack & pulse...knickers in a twist.

[Len Ovens]

On Wed, 6 Jun 2018, Mac wrote:

> 
> 
> On Tue, Jun 5, 2018 at 3:20 PM, Len Ovens <len at ovenwerks.net> wrote:
>       On Tue, 5 Jun 2018, Mac wrote:
>             surround71:CARD=PCH,DEV=0
>                 HDA Intel PCH, ALC892 Analog
>                 7.1 Surround output to Front, Center, Side, Rear and
>             Woofer speakers
>             How does jack decide to only do 2 playback_1,_2?
>
>             I take it there is something else in alsa startup that
>             says provide for example
>             surround71
> 
>
>       I do not know if jack will accept surround71:PCH,0 for device. I do
> 
> Apparently not. I tried "jack_control dps device surround71:PCH,0" and still got
> playback_1,_2. (There are also surround21, 41, etc. none of those changed
> anything either.)
> As for hdajackretask, when I tried to "Apply now" I got a device busy message. I
> didn't try "Install boot override".

Is jack running? is anything making noise through pulse? Can pulse do 7.1? 
If anything is actively using PCH,0 then hdajackretask (or any other 
utility) would not be able to change things. You may need to set the 
device profile in pavucontrol to "Off" as well as making sure jack is 
stopped before hdajackretask will be able to do things. I was able to 
reset a jack in my case, but then I am not using the device for jack or 
pulse. When I busied the device up with zita-j2a I was still able to 
change one of the pin uses.... but, my zita-j2a process then started 100% 
cpu :) This may have something to do with changing the current input port 
into an output port :P (It took a kill -9 to stop that zita-j2a)

>       In my case the real answer is I don't know. I tend to disable any
>       internal audio device to clear up one more thing that may interfere
>       with "real audio".
> 
> Agreed, when in my studio or at a venue where I have "real audio". But, sitting
> in my hotel room or elsewhere, with only my laptop and it's internal
> hardware...one must improvise. ;)
> 
> (Not saying I would need more than 2 outputs in such a case, that's just a "hey,
> the thing has more than two channels, how do get to them" musing.)

I can understand that. The most surefire way I can think of is to wade 
through the pulseaudio code (assuming pulse can be set to surround7.1). 
Also, assuming a laptop, while the audio setup inside may have 8 outputs, 
there may be fewer physical jacks to use anyway. My laptop has only two 
jacks for example for a maximum of 4 channels, some have three, but I have 
not seen any more than that. I think HDMI can go to 5.1 as well (but 
needs an non-free encoder... that could be old info, newer hdmi may do 6 
or 8 channels natively).

Of course in the end Jack may just lack the code to set the device for 
other channel counts. I don't know alsa coding well enough to know.

--
Len Ovens
www.ovenwerks.net