[mythtv] [mythtv-commits] Ticket #3690: Prebuffering pauses with ivtv sinceffmpeg resync

Matt skd5aner at gmail.com
Wed Aug 8 01:21:04 UTC 2007

On 8/6/07, Anduin Withers <awithers at anduin.com> wrote:
> >  Since the ffmpeg resync - [13655] - one of my frontends has had issues
> >  playing back recordings from the PVR150 in the backend. If I roll back to
> >  13654 playback is smooth but on 13655 it's unwatchable (prebuffering
> >  pauses every 2 seconds or so). This only occurs with recordings from the
> >  PVR150, playing from the DVB cards is fine.
> [...]
> > Ticket URL: <http://svn.mythtv.org/trac/ticket/3690>
> I had one frontend that was hitting this bug and so spent a good chunk of
> yesterday looking in to 3690.
> It looks like libavformat/mpeg.c mpegps_read_pes_header line 1446:
> url_fseek(&s->pb, last_sync, SEEK_SET);
> This will result in calls to RingBuffer::Seek() with seeks to where we are,
> not too bad except for unnecessary things like a potential network call and
> worse, a ResetReadAhead call.
> For me the difference between unwatchable even at 1x and, as it was back at
> 13654, is a check early in RingBuffer::Seek(). My change is to do nothing
> (not literally nothing, return the right values) when SEEK_SET(where we are)
> and SEEK_CUR(0).
> Does anyone object to this change? (I'll attach the patch to the ticket
> later tonight)
> --
> Anduin Withers
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Anduin... I'll be happy to test a patch to let you know if it
addresses my issues!  This has probably been one of the very few bugs
out there that I've ever experienced in trunk that has cause my myth
system to be completely unusable.  Thank you for taking the time to
research and address this issue.  I see the patch is there now.  I
don't have time tonight to test, but hopefully can test tomorrow.


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