[pulseaudio-discuss] Splitting a 7.1 device into virtual 5.1 + 2.0 devices?

[Tanu Kaskinen]

On Tue, 2016-04-12 at 22:32 +0200, 紅 蒼穹 wrote:
> > On Sat, 2016-04-09 at 16:22 +0200, 紅 蒼穹 wrote:
> > > When I have lfe remixing = yes (default):
> > > - LFE is mixed to stereo output when downmixing from 5.1
> > > - there are no low frequencies present at all in 5.1 output when
> > > playing a stereo track.
> > 
> > LFE remixing is supposed to move low frequencies from all other
> > channels to the LFE channel by default. Are you saying that the LFE
> > channel doesn't get low frequencies either?
> 
> At least I can't hear any on any non-5.1 content. It is correctly
> present with 5.1 content though

That sounds bad. I opened a bug report: 
https://bugs.freedesktop.org/show_bug.cgi?id=95021

> Speaking of volumes, is there an option to somehow boost only the LFE
> in pulseaudio? Changing it with alsamixer gets overridden next time I
> use my media keys.

You can use e.g. pavucontrol to control the individual channels (with
pavucontrol you need to first turn off the "lock channels together"
option, represented by the shield icon). The media keys might still
lose the per-channel differences, though.

> > > Btw, the current setup triggers that bug I reported [1] in a slightly
> > > different way: connecting the headphones switches the device to 2.0
> > > mode, unplugging even without restarting leaves the device in 2.0
> > > mode. This mutes the remapped stereo output.
> > 
> > I've forgot, do you have a separate headphone connector in addition to
> > the 7.1 connectors? And do you mean here that using the separate
> > headphone connector switches to 2.0 mode? That would be expected,
> > because plugging in headphones makes other outputs unavailable. When
> > you unplug the headphones, however, the card should switch back to 7.1
> > mode if you had manually selected that profile previously. If you
> > haven't selected it manually previously, then leaving the profile at
> > 2.0 is also expected.
> 
> My card is set to 7.1 + stereo input at first - manually, but it's
> also what the card was set to the first time I installed pulseaudio,
> if I remember correctly. So it's manual but also the default. I plug
> my stereo headset to the front headphone jack (so yes, a separate
> one). The card switches to stereo input and mutes rear output as
> expected. I unplug the headphones from the front jack. The card
> unmutes /only the front channels/, leaving the speakers (connected to
> the side channels socket) muted. It also stays in stereo input
> instead of changing back to 7.1 + stereo input.

The next release will have some changes related to this area (if my
patches get accepted). If it still doesn't work in 9.0, then this needs
more investigation.

-- 
Tanu