[mythtv-users] Jerky playback on BBC HD Chennels

[HP-mini]

On Sun, 2013-01-27 at 17:25 +0000, Fred Watt wrote:
> On 27/01/13 16:51, Tim Draper wrote:
> 
> > 
> > 
> > On 25 January 2013 06:52, Fred Watt <fredwattmythtv at gmail.com>
> > wrote:
> >         On 24/01/13 21:03, Tim Draper wrote:
> >         
> >         > Are there any plans to revert this in 0.26-fixes? i too am
> >         > suffering with BBC HD recordings since a recent update.
> >         Me too - awful.  Massive regression.

> > I've just been looking at this to see if theres been any updates -
> > none yet.
> > for reference of the bug - http://code.mythtv.org/trac/ticket/11356
> > 
> > re-reading through thread and the bug tracker info, it's down to
> > ffmpeg.... since i tend to update my entire system rather than just
> > mythtv, is this something mythtv can help out with, or are we
> > waiting on a fix from the ffmpeg devs to fix this annoyance??
> > atleast the 'work around' is to ammend the recording rules for BBC
> > One HD shows, and rely on BBC One (SD) for the recordings.
> > Interestingly people are reporting it on just one channel; BBC HD,
> > i'm having issues on BBC One HD and ITV HD aswell! (C4 HD doesn't
> > exhibit the issue)
> > 

> Yes we're stumped as well.... nearly all of our viewing is now BBC HD,
> and over the last two weeks we're unable to watching anything easily.
> What does seem to work is 'livetv', I watched the tennis today in HD
> and it started out stuttery but after 30 seconds was completely
> watchable.  The recordings on the other hand are frame jerky.  I
> wonder why that is?
> 
> Correct me if I am wrong, but my understanding is that ffmpeg is
> statically linked.  So it does not matter which version is installed
> on our ubuntu boxes.  Like you, these days I use the repositories, so
> we need for a fixed version.
> 
> Very frustrating.  I can watch using another player but it's all a
> faf... as I prefer using mythfrontend.
> _______________________________________________

If livetv works then the seektable generation must be different between
recording & watching live. Or is it the recording start?

Can you watch these recordings from "videos" ?
Seektables are optional for "videos", none of mine seek correctly
without generating them. But your recordings might play smooth(er)
without.

FWIW MythTV does make a mess of the beginning of recordings..(There is a
ticket/patch/commit that improves this). This causes problems with
transcoding & cut frame accuracy.

You could try:
- find (with ffprobe) first "coded picture number" byte offset & cut off
file beginning with "dd".
- rebuild seektable with mythtranscode or mythcommflag (or mythutils).
- write a script with "ffprobe" & generate the right seektable offsets. 

Can you easily upload (somewhere) a 1 minute recording ?
(could cut end off with "dd" but I do need the start untouched)

For me, Ticket #11159 caused jerky/judder on recording discontinuities
(cut files) on SD channels.

I find it is possible to induce this judder/jerky playback on any H264
recording by messing around in the cutlist editor at the start.

Brett.