[mythtv] Aspect Change problems

Derek Atkins warlord at MIT.EDU
Sat Nov 22 14:02:22 EST 2003

"Edward Wildgoose" <edward.wildgoose at frmhedge.com> writes:

> Just to confirm that I tried the latest CVS and it still have the problem
> with that wierd jitter developing after any change in aspect ratio in the
> source stream.  The problem with cvs seems to be in
> VideoOutput::InputChanged, something in there to do with resetting video
> buffers is causing something which triggers this jitter.  The effect is very
> odd, video frames jitter forwards and backwards in time...

I'm seeing that same behavior here -- not with an aspect change but
with a damaged video frame.  I've got a test video if anyone wants a
copy (it's 300MB, but I'll happily press onto a CD and send it if you
want to see the problem).

Basically, I get:

[mpeg1video @ 0x89b9f78]ac-tex damaged at 2 26
[mpeg1video @ 0x89b9f78]concealing errors
[mpeg1video @ 0x89b9f78]Warning MVs not available
[mpeg1video @ 0x89b9f78]slice below image (69 >= 30)
[mpeg1video @ 0x89b9f78]slice below image (37 >= 30)
[mpeg1video @ 0x89b9f78]slice below image (55 >= 30)
[mpeg1video @ 0x89b9f78]concealing errors
[mpeg1video @ 0x89b9f78]slice below image (38 >= 30)
[mpeg1video @ 0x89b9f78]concealing errors

And then the jitter starts..  If I can jump past the "bad frame" then
it doesn't jitter.

Strangely, this problem ONLY occurs in Myth with software decode.  I
can use mplayer and the video is just fine (even when I force the
ffmpeg a/v codecs).  Also, output to a pvr-350 works fine, with a
small correction around when the video is damaged.


       Derek Atkins, SB '93 MIT EE, SM '95 MIT Media Laboratory
       Member, MIT Student Information Processing Board  (SIPB)
       URL: http://web.mit.edu/warlord/    PP-ASEL-IA     N1NWH
       warlord at MIT.EDU                        PGP key available

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