[pulseaudio-discuss] Help with CMI8768 Please

Jim Duda jim at duda.tzo.com
Sat Sep 12 07:54:18 PDT 2009

> This setup works very well, however, I want to stop using ALSA directly,
> and instead use pulse for obvious reasons.
> I'm struggling to get the same features to work with pulse,
> specifically, the 6 channel upmixing. I don't know what I'm
> doing wrong.

This morning I realized that pulse was having trouble opening my alsa a52
plugin.  So, I downloaded alsa-plugins-1.0.21 and recompiled the a52 plugin
and installed.

Now, If I start pulse without hal and use a52 like this:

load-module module-alsa-sink device=a52encode rate=48000 channels=6 sink_name=alsa_surround

### Automatically load driver modules depending on the hardware available
#.ifexists module-hal-detect.so
#load-module module-hal-detect
### Alternatively use the static hardware detection module (for systems that
### lack HAL support)
#load-module module-detect

Then I get the proper upmixing provide by pulse.  The alsa a52 plugin is doing
the analog to digital encoding to dolby digital for my surround system.

Unfortunately, although this works great for music, attempting to play mpeg
videos is a problem.  When I use mplayer to play mpeg videos with 5 channel
sound, mplayer uses liba52 to decode the channels.  When playing through
pulse and subsequently a52 (to go back to digital), the sound is all choppy.
I suspect this has to do with the a52 plugin as I've read in various posts
that it may not be thread safe.

I'm hoping I'm just confused on how best to utilize pulse with spdif
to my surround box.  I want to be able to upmix my stereo to 6 channels
over digital and also be able to play my mpegs via mplayer and dvds
via xine all over digital spdif using pulse in the middle.  I just
cannot seem to get it all working properly.



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