[mythtv-users] Help with prebuffer/audio issues. WAS: Upgrade from 0.21-fixes 18314 to 20500: frames behind audio problems?

Tom Dexter digitalaudiorock at gmail.com
Mon May 11 19:47:18 UTC 2009


On Sat, May 9, 2009 at 11:53 AM, Tom Dexter <digitalaudiorock at gmail.com> wrote:
> On Thu, May 7, 2009 at 1:05 PM, Tom Dexter <digitalaudiorock at gmail.com> wrote:
>> I've been running a custom Gentoo ebuild of 0.21-fixes 18314 for some
>> time now.  Today I made my self an ebuild to upgrade to rev 20500 out
>> of SVN 0.21-fixes.
>>
>> I ended up having to downgrade back to 18314.  On any LiveTV 1080i
>> broadcasts I got hammered with these errors:
>>
>> 2009-05-07 11:55:00.011 NVP: Video is 3.0149 frames behind audio (too
>> slow), dropping frame to catch up.
>> 2009-05-07 11:55:00.221 NVP: Video is 3.23074 frames behind audio (too
>> slow), dropping frame to catch up.
>> 2009-05-07 11:55:00.226 NVP: Video is 3.10487 frames behind audio (too
>> slow), dropping frame to catch up.
>> 2009-05-07 11:55:00.339 NVP: Video is 3.00147 frames behind audio (too
>> slow), dropping frame to catch up.
>> 2009-05-07 11:55:00.438 NVP: Video is 3.22619 frames behind audio (too
>> slow), dropping frame to catch up.
>> 2009-05-07 11:55:00.445 NVP: Video is 3.22883 frames behind audio (too
>> slow), dropping frame to catch up.
>> 2009-05-07 11:55:00.556 NVP: Video is 3.20982 frames behind audio (too
>> slow), dropping frame to catch up.
>> 2009-05-07 11:55:00.559 NVP: Video is 3.08919 frames behind audio (too
>> slow), dropping frame to catch up.
>> 2009-05-07 11:55:00.705 NVP: Video is 3.13379 frames behind audio (too
>> slow), dropping frame to catch up.
>> 2009-05-07 11:55:00.808 NVP: Video is 3.20506 frames behind audio (too
>> slow), dropping frame to catch up.
>> 2009-05-07 11:55:00.812 NVP: Video is 3.1081 frames behind audio (too
>> slow), dropping frame to catch up.
>> 2009-05-07 11:55:00.923 NVP: Video is 3.02017 frames behind audio (too
>> slow), dropping frame to catch up.
>> 2009-05-07 11:55:01.022 NVP: Video is 3.24981 frames behind audio (too
>> slow), dropping frame to catch up.
>> 2009-05-07 11:55:01.026 NVP: Video is 3.23905 frames behind audio (too
>> slow), dropping frame to catch up
>>
>> ...and the video was jerky and had unwatchable tearing.  Oddly enough
>> 1080i pre-recorded shows were just fine.  I'm currently using the new
>> fieldorder deinterlacer, but I got the same results when switching to
>> Bob x2, which has worked fine for me for years.
>>
>> Luckily I had no problem downgrading back to 18314, and LiveTV is fine
>> now....maybe in about a week my heart will slow down a bit :D.
>>
>> Unfortunately I couldn't leave it that way long enough to do much
>> debugging, as I really needed to have a working system.
>>
>> Anyone have any ideas as to what change between those revs might have
>> caused that?
>>
>> Tom
>>
>
><snip>
>
> Just another note...I have no idea if it could be related or not:  I
> have a native 1080i display and have to use this patch to use either
> Bob x2 or fieldorder:
>
> http://svn.mythtv.org/trac/ticket/2903
>
> Any suggestions would be greatly appreciated.  Luckily I have a good
> working system as things stand, but I'd hate to be stuck at this rev.
> If I get some clue as to what changes between 18314 and 20500 might
> influence this, I can, without too much trouble, try upgrading to
> different intermediate revs to narrow this down.  Thanks!
>
> Tom
>

Wow...I finally figured out what was happening.  My rev 20500 ebuild
was using a version of that 2903 patch that wasn't working correctly
and was never doubling the refresh rate as it should.  I hadn't
noticed that when watching recordings, my deinterlacer was being
rejected as a result, and there was no deinterlacer being used at all.
 However for some reason, LiveTV was allowing me to use the fieldorder
deinterlacer even though the patch had not properly doubled the
refresh rate.  I'm not clear why that happened, but the result was the
mess described above where it never thought the video was ever caught
up.

Correcting that patch seems to have made rev 20500 work fine for me.

Tom


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