[mythtv-users] Jitters during playback

Michael T. Dean mtdean at thirdcontact.com
Sat Jan 28 16:15:31 UTC 2012


On 01/28/2012 03:06 AM, Mark Kendall wrote:
> On 28 January 2012 04:30, Mitchell Gore wrote:
>> When I play back many recording I constantly get jitters/pixelations and
>> sometimes a complete drop of vido playback.  In the frontend log I see:
>>
>> 2012-01-27 22:16:33.328 [ac3 @ 0x9d8ae0]frame CRC mismatch
>> 2012-01-27 22:18:21.705 AFD Error: Unknown audio decoding error
>> 2012-01-27 22:18:33.646 [ac3 @ 0x9d8ae0]incomplete frame
> These errors suggest to me a signal issue.
>> mitchell at mythfe:/var/log/mythtv$
>> mitchell at mythfe:/var/log/mythtv$
>> mitchell at mythfe:/var/log/mythtv$ tail -n 400 mythfrontend.log
>> 2012-01-27 22:10:30.344 AFD Error: Unknown audio decoding error
>> 2012-01-27 22:10:30.349 [ac3 @ 0x9d8ae0]frame CRC mismatch
>> 2012-01-27 22:10:30.378 [ac3 @ 0x9d8ae0]frame sync error
>> 2012-01-27 22:10:30.378 AFD Error: Unknown audio decoding error
>> 2012-01-27 22:10:30.433 [ac3 @ 0x9d8ae0]frame CRC mismatch
>> 2012-01-27 22:10:30.460 [ac3 @ 0x9d8ae0]frame sync error
>> 2012-01-27 22:10:30.461 AFD Error: Unknown audio decoding error
>> 2012-01-27 22:10:32.518 Player(0): Waited 100ms for video buffers
>> AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
>> 2012-01-27 22:10:42.148 Player(0): Waited 100ms for video buffers
>> AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
>> 2012-01-27 22:10:42.157 Player(0): Waited 100ms for video buffers
>> AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
>> 2012-01-27 22:10:54.930 [ac3 @ 0x9d8ae0]frame CRC mismatch
>> 2012-01-27 22:10:54.962 [ac3 @ 0x9d8ae0]frame sync error
>> 2012-01-27 22:10:54.962 AFD Error: Unknown audio decoding error
>> 2012-01-27 22:10:55.180 [ac3 @ 0x9d8ae0]frame CRC mismatch
>> 2012-01-27 22:10:55.210 [ac3 @ 0x9d8ae0]frame sync error
>> 2012-01-27 22:10:55.211 AFD Error: Unknown audio decoding error
>> 2012-01-27 22:10:56.046 [ac3 @ 0x9d8ae0]frame CRC mismatch
>> 2012-01-27 22:10:56.076 [ac3 @ 0x9d8ae0]frame sync error
>> 2012-01-27 22:10:56.076 AFD Error: Unknown audio decoding error
>> 2012-01-27 22:10:56.254 [ac3 @ 0x9d8ae0]frame CRC mismatch
>> 2012-01-27 22:10:56.267 [ac3 @ 0x9d8ae0]frame sync error
>> 2012-01-27 22:10:56.268 AFD Error: Unknown audio decoding error
> and perhaps an even worse signal...
>> My source is a Prime Cable card.  I get nearly a 100% signal
>> strength/quality acording the the HDHR meters.  Im kinda at a loss on how to
>> fix this.  Is it caused by VDPAU?
> Have you tried playing back with vdpau disabled?

FWIW, I had been getting a lot of OTA recordings that showed 
"jitters/pixelation" during playback.  When I switched my profile from 
VDPAU decode + VDPAU render to ffmpeg decode + VDPAU render, all the 
issues went away.  I don't think it's a problem with MythTV code, but a 
problem with VDPAU's ability to cope with small errors in the stream due 
to small signal issues.

Mike


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