[mythtv-commits] Ticket #7496: pulseaudio A/V sync
MythTV
mythtv at cvs.mythtv.org
Tue Nov 3 12:05:06 UTC 2009
#7496: pulseaudio A/V sync
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Reporter: Alan Calvert <cal@…> | Owner: jyavenard
Type: enhancement | Status: new
Priority: minor | Milestone: 0.23
Component: MythTV - Audio Output | Version: head
Severity: low | Mlocked: 0
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As requested by danielk (ref #5473), a ticket to focus efforts to improve
pulseaudio sync/latency.
Ref <http://pulseaudio.org/wiki/LatencyControl>
So far the approach to buffer setup has been to choose params that seem
comfortable for myth, then try to persuade pulseadio to conform. Pulseadio
has some wonderful attributes, but "accommodating" is not necessarily one
of them. Patch pulse-latency-001.patch goes the other way - try to set
pulseaudio latency to what's required, and have myth's fragment_size &
soundcard_buffer_size conform to pulseaudio's ultimate choice of buffer
metrics.
PA_STREAM_ADJUST_LATENCY has limited utility in myth's quest for "out of
the box" performance. It depends on having tsched=1 in the load-module
module-alsa-sink params, which according to the above reference "... is
the default for most modern distributions, with the infamous exception of
Ubuntu" . Since ubuntu is possibly the main reason for even bothering with
pulseaudio in myth, that's inconvenient. I've tried this with both
tsched=1 and tsched=0, and sync does seem to be a little tighter in both
cases. The experience of others would be interesting.
--
Ticket URL: <http://svn.mythtv.org/trac/ticket/7496>
MythTV <http://www.mythtv.org/>
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