[pulseaudio-discuss] xine 5.1 channel downmix / gmplayer pulse output

Lennart Poettering lennart at poettering.net
Mon May 28 16:04:44 PDT 2007

On Fri, 11.05.07 18:06, Nikolaus Filus (nfilus at gmx.net) wrote:

> Ok, so now I confirmed the channel maps are different. But where can I downmix
> 5.1 to 2? Where can I read more about possible setups?
> - configure sink for 5.1 (my notebook can't do that, but this would be nice-to-know)
> - downmix channels
> - select n channels and pass to sink

It all depends what you pass to the module-alsa-sink module.


You can alter the channel map by passing
"channel_map=right,left,front-left,.." and so on as module
parameter. That will overwrite the channel names and their order for
the sink.

PA will not downmix channels. It will only copy or drop
channels. Channels are mapped by names. I.e. if a sink has
fron-left,front-right,lfe and a stream just has
front-left,front-right, then the lfe will get silence. The only
special rule is that we mix front-left+front-right into mono, and copy
mono to front-left and front-riught.

In essence: the rules are vey basic. We don't do any dolby surround
coding. No lowpass filtering for LFE. (Which btw, is another item on my todo list)

Please read http://pulseaudio.org/wiki/CLI for a quick introduction
into using the PA cli for configuration of all these things.

> >> 2. mplayer works fine, but gmplayer freezes after few played samples and waits
> >> for some event. I get a lot of
> >> futex(0x8bb0af0, FUTEX_WAKE, 1)         = 0
> >> in strace output.
> >> Sometimes there is a window showing up: "AO: [pulse] Failed to get sink input
> >> info: Timeout"
> > 
> > No idea. I've only tested mplayer directly. Have you checked that it
> > doesn't call mplayer with some odd parameters?
> gmplayer is only a link to mplayer, which automatically selects -gui and chooses
> it's configuration from gui.conf instead of mplayer.conf. I started from a clean
> a clean configuration, so there are no user options involved.
> On IRC I got the hint to select softvol for mplayer, where the problem doesn't
> occur. So may mplayer in gui mode do something on the mixer, what can make it fail?

I didn't know mplayer now contains support for PA? Or doesn't it? Is
this the PA plugin for alsalib? 

(I once prepared a PulseAudio patch for Mplayer and submitted it
upstream -- but they refused it because they didn't like our name
change from polypaudio to pulseaudio. I didn't pursue this any
further, to say the least.)


Lennart Poettering                        Red Hat, Inc.
lennart [at] poettering [dot] net         ICQ# 11060553
http://0pointer.net/lennart/           GnuPG 0x1A015CC4

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