Arch Linux

nle

Member

Registered: 2014-02-15

Posts: 3

Problem with 5.1 passtrough (SPDIF) with PulseAudio

Hi guys, I have been struggeling for a while now.

I have optical cable connected from my Intel IEC958 to my Samsung Surround system through SPDIF

The surround sound works perfectly if I kill pulseaudio and configure passthrough correctly in VLC. If I test the same file and settings with PulseAudio enabled, the front left, center and front right works fine, but then when it tests the back speakers I get audio on all (front, center and back. Front speakers have more volume).

Why is this? Any one have any advice?

Should I just get rid of PulseAudio all together and stick with ALSA?

aplay -l
**** List of PLAYBACK Hardware Devices ****
card 0: Intel [HDA Intel], device 0: ALC889A Analog [ALC889A Analog]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 0: Intel [HDA Intel], device 1: ALC889A Digital [ALC889A Digital]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 1: NVidia [HDA NVidia], device 3: HDMI 0 [HDMI 0]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 1: NVidia [HDA NVidia], device 7: HDMI 1 [HDMI 1]
  Subdevices: 1/1
  Subdevice #0: subdevice #0

Last edited by nle (2014-03-05 21:05:32)

emeres

Member

Registered: 2013-10-08

Posts: 1,570

Re: Problem with 5.1 passtrough (SPDIF) with PulseAudio

Should I just get rid of PulseAudio all together and stick with ALSA?

If that still satisfies your needs, then yes. PulseAudio is just a sound server running on top alsa/oss anyway (additional layer). As fas as I understand PA tries to dynamically and automatically configure for every hardware setup, so it is probably configured wrong, and instead of using surround it (up)mixes streams thinking there is no proper surround hardware or that input stream is not proper surround. So you either have to specify using surround output, which you probably already have, or look at current configuration more closely (PA uses modules, some are still problematic). The only advantage of using PA I see, is per application volume control, however this can be (pseudo)done under alsa with some manual configuration (using custom pcms, softvol and setting default device through environment variables). I dropped PA since is was too much trouble.
PS. You should have an iec958 device under system pcms (aplay -L), using that may be more comfortable with using other applications with other outputs.

Last edited by emeres (2014-03-05 22:48:30)

V1del

Forum Moderator

Registered: 2012-10-16

Posts: 25,081

Re: Problem with 5.1 passtrough (SPDIF) with PulseAudio

If you don't want to get rid of pulseaudio, have you taken a look at https://wiki.archlinux.org/index.php/Pu … nd_systems ?

nle

Member

Registered: 2014-02-15

Posts: 3

Re: Problem with 5.1 passtrough (SPDIF) with PulseAudio

Thanks guys, I have tested a bit with the pulseaudio config files, but no go.

I'll give it a few more tries, and if it doesn't work, I'll just disable it and stick to ALSA.