[pulseaudio-discuss] why is this giving an error and failing to start?

Colin Guthrie gmane at colin.guthr.ie
Wed Dec 22 01:41:59 PST 2010

'Twas brillig, and Christ Schlacta at 21/12/10 19:29 did gyre and gimble:
> load-module module-combine sink_name=mpd.002 slaves=mpd.001 channels=2
> load-module module-remap-sink sink_name=mpd.003.lr master=mpd.002
> channels=2 master_channel_map=left,right channel_map=left,right
> load-module module-remap-sink sink_name=mpd.003.rl master=mpd.002
> channels=2 master_channel_map=right,left channel_map=left_right
> load-module module-combine sink_name=mpd slaves=mpd.003-rl,mpd.003.lr
> channels=2
> update-sink-proplist raw device.description="actual soundcard"
> update-sink-proplist xbmc device.description="XBMC stereo output"
> update-sink-proplist mpd device.description="MPD Stereo output"
> ### ENd config snippet.
> The problem is that I'm getting some perculiar errors on starting
> pulseaudio:
> Dec 21 11:19:06 rebirth pulseaudio[14764]: module-combine.c: No slave
> sinks specified.

Hmm, interesting. Any idea which of the two combines this message is
coming from?

> Dec 21 11:19:06 rebirth pulseaudio[14764]: module-remap-sink.c: No
> remapping configured, proceeding nonetheless!

There appears to be a typo in your last remap where you have
"channel_map=left_right" when I presume you mean "channel_map=left,right"

> then, despite the fact that it says it's proceeding, it simply proceeds
> to exit with no further log entries.

Hmm, interesting. Can you run manually via pulseaudio -vvvv (with the
appropriate --system argument - you'll have to run as root and it should
drop privs to the "pulse" user)

> So you may ask what I'm trying to accomplish.  I'm trying to downmix
> stereo audio to mono before passing it off to the virtual sink mpd.001. 
> the reason is that I've got a blown speaker, that I've gotten rid of and
> only one speaker left.  THis christmas music sounds terrible when you
> can't hear alvin, or you can't hear simon and theodore. 

Oh Noes! :p

> If you can help
> me fix this existing config, or find a better way to downmix my music to
> mono (actually mix l and r, not just one or the other) I'd be very
> happy, and the children's christmas would be immeasurably merrier!

One potentially easier (but maybe not as nice?) way would be to create a
null sink with a single channel then use module-loopback sink to connect
it's monitor to your real sink. It should automatically upmix the mono
null sink to stereo on your real sink.... not 100% sure this will work
but it should do.




Colin Guthrie

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