PA loses mono audio support when remixing is disabled

[Sam Stone]

I set enable-remixing = no to prevent stereo sound upmix on my 5.1 speakers, but with this option i can't use microphone in skype, the input level indicator in gnome-volume-control (i'm using ubuntu) doesn't show anything on my both soundcards (ALC889A & Audigy2 value with stereo duplex and analog 5.1+stereo input setup accordingly). With "enable-remixing = yes" microphone works fine.

[lennart]

If you disable remixing all kind of remixing is disabled, including stereo-to-mono and mono-to-stereo remixing. Most likely Skype is opening the audio stream in a different channel mapping then PA has opened the audio hw

[coling]

Lennart, do you think this is something that Skype should not assume? Personally, I think this is one of the beauties of PA, the ability to say, "I want to record Mono" adn then let the server work it out?

Sam, if you want a solution that works, I'd try something like:

load-module module-remap-sink sink_name=stereo sink_properties="device.description='Stereo'" master=INSERT_51_SINK_NAME_HERE channels=2 master_channel_map=front-left,front-right channel_map=front-left,front-right remix=no

This should create a virtual device for you that will only use the front speakers and you can move your pure stereo streams to this virtual device to ensure it wont upmix on an app-by-app basis.

[lennart]

No. Skype is behaving correctly.

This just tells us that one either should not disable remixing or we should allow the remixing to be more fine-grainedly controlled.

i.e.

upmix-lfe = yes/no
downmix-lfe = yes/no
upmix-mono = yes/no
downmix-mono = yes/no
upmix-rear = yes/no
downmix-rear = yes/no

and so on.

[Sam Stone]

Coling, with your example I have the same problem: I must manually switch output device for normal 2.0 or 5.1 sound (but it's more flexible :) I can change output for only one application through pavucontrol, not for all system), e.c. for stereo music in mplayer I choose "stereo" sink, for movie with surround sound I must set 5.1 sink to get all my speakers work. I hope I'm clearly written :) I temporarily deceiving skype with

PULSE_SERVER=fake_ip skype

for working through alsa.

Sorry for my bad english :)

[Captain Chaos]

Is anything happening on this?

If I understand it correctly, a pulseaudio user with more than two loudspeakers currently has three choices:

1. Accept that all audio that plays is sent to all speakers, whether or not that's appropriate 2. Accept that mono audio does not play at all 3. Jerry rig a complicated system with virtual devices, which will only partly solve the problem (namely only for programs which allow you to choose the device they play to)

To me all these options are unacceptable. People with surround sound systems should not be punished by having their audio not work at all, or be played over the wrong speakers. Instead, pulseaudio should intelligently choose which speakers to direct the audio to.

I find the suggestion that remixing is needed to allow mono sound to be played on 5.1 speakers a bit odd. Surely mono sound could be played over the center speaker, no remixing required? Pulseaudio currently already correctly plays stereo sound over just the front left and right speakers when remixing is turned off, surely it would not be hard to similarly direct mono channels to the center speaker?