[pulseaudio-discuss] Transporting sound from 'mpd' server to laptop

Paul LeoNerd Evans leonerd at leonerd.org.uk
Sun Oct 20 16:37:38 CEST 2013

On Sun, 20 Oct 2013 07:25:23 +0100
Tanu Kaskinen <tanu.kaskinen at linux.intel.com> wrote:

> Restarted what? PulseAudio or MPD? I would expect that restarting MPD
> is enough.

Restarting the tunnel; running my previously-pasted script in "down"
then "up" mode.

> Latency can only increase only if there is some buffer that is
> growing. module-tunnel doesn't have such buffer. It sounds like MPD
> is working so that it writes at a constant pace to an internal
> buffer, and reads from the buffer at the rate that PulseAudio asks
> for more data. If network glitches occur, PulseAudio will ask less
> often, so MPD's buffer will get larger and larger. If this
> speculation is true, then MPD should be fixed. It should define some
> maximum size for the buffer. 30 seconds is silly. And if you're
> playing local files, this whole problem shouldn't exist, because MPD
> should decode the files at the rate PulseAudio is consuming the data,
> not at a constant wall-clock rate.

I'm not sure that's consistent with what is happening. When I press the
MPD pause button, it still takes a long time for the sound to stop
playing. then again a long time after I resume it before the sound
comes out again.

Also, my MPD has multiple outputs; pushing to both pulse and the
shoutcast server, so it couldn't wait for one output to catch up with
the sound by delaying the others - it has to just generate sound at its
own rate and let the outputs keep up as best they can.

Again to clarify - I am happy for pulse to occasionally drop frames of
audio in order to keep the end-to-end system latency bounded. It sounds
like so far it isn't capable of doing so.

Paul "LeoNerd" Evans

leonerd at leonerd.org.uk
ICQ# 4135350       |  Registered Linux# 179460
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