[pulseaudio-discuss] My attempt to reduce latency with pacat and tvtime

Steven Elliott selliott4 at austin.rr.com
Tue Mar 27 20:07:00 PDT 2012

On Tue, 2012-03-27 at 12:16 -0500, Pierre-Louis Bossart wrote:
> On 3/26/2012 11:54 PM, Steven Elliott wrote:
> > I use tvtime (an open source TV application) to watch TV on my Fedora 16
> > system.  As some of you may know forwarding audio from the sound card
> > built into the TV tuner card to the primary sound card is not done by
> > tvtime.  There are various ways of forwarding the audio including SoX,
> > module-loopback, etc. but I've had the best luck (least latency) using
> > pacat in a manner similar to what this webpage describes:
> >
> > http://thelinuxexperiment.com/guinea-pigs/tyler-b/fix-pulseaudio-loopback-delay/
> >
> > But with a change that I've made to pacat that I'd like to share in case
> > it's helpful.
> Why not use module-loopback with latency set to a low value? Worked well 
> when I last used it.

I have tried it, but I've had better luck with the pacat solution I
outlined.  I've tried various latency times for each.

I just noticed that pa_stream_writable_size() typically returns values
that make sense for 23 msec instead of the 1 msec that I have latency
set to (I know it's not realistic to have latency be that low, but I
thought I'd try to get as close as possible).  Anyway, maybe that's
something I should investigate further since that 23 msec is only part
of the total latency.

|  Steven Elliott  |  http://selliott.org  |  selliott4 at austin.rr.com  |

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