[mythtv-users] Re: Jerky Video after transcode MPEG2->MPEG4

Gavin Haslett gavin at nodecaf.net
Sun Jun 26 15:19:06 UTC 2005

On Sun, 2005-06-26 at 11:06 +1000, Mike Harris wrote:
> I recently upgraded to Myth 0.18. After doing so, transcoding video from 
> MPEG2 -> MPEG4 results in jerky video - it looks as though some frames 
> are being dropped.

You know, I notice this a little bit, too. I suspect in part it's due to
using XvMC. It will do motion compensation on MPEG2 but not MPEG4. I
feel that my slower processor (800Mhz AMD) may also contribute to this
problem. If I disable XvMC I notice a little bit of jerkiness and jitter
that seems to be consistent with the results I get from an MPEG4 stream.

All I do for now is just record MPEG2 at 2200 bps and don't re-encode. I
find the video quality to be comparable (I barely notice the difference
on my SD television or on my good-quality monitor in my study) and it
doesn't heat up my living room re-encoding the video any more.

Also, I have noticed that the same recordings seem to play with no
jerkiness at all on my study computer (dual 933 Intel), either MPEG4 or
MPEG2. I use the same video card in my study computer, and I'm running
it as a frontend only speaking to the backend across 100Mb/s LAN. Other
than the resolution and processor, the configurations are comparable.


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