[mythtv-commits] Ticket #7496: pulseaudio A/V sync

[MythTV]

#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.

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Ticket URL: <http://svn.mythtv.org/trac/ticket/7496>
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