[mythtv-users] Very slight jitter on high power machine

Doug Larrick doug at ties.org
Tue Dec 14 12:46:55 UTC 2004

Joe Barnhart wrote:
> --- Brad Templeton <brad+myth at templetons.com> wrote:
>>By jitter I refer to what appear to be dropped
>>frames, slight skips in
>>smooth motion during periods of high motion.   Not
>>the "Sound is freaking
>>out" constant jitter or actual slow playback.
> I've noticed this too, and I describe it almost as
> "cogging" because the hiccup is very regular.  For
> example when a camera pans across a scene I see smooth
> panning interrupted by regular jerks.  

You might also check that your video refresh rate is very close to 59.94 
(60 * 1000/1001) Hz (for US).  If it's not, Myth will have to 
periodically extend or skip a frame to keep in sync.

If you're not running AC3 passthrough, you can instead try turning on 
"use video as timebase," which will warp the audio instead of the video. 
  I am not sure if this was changed to use the new libmythsoundtouch 
stuff, or if it still audibly speeds up/slows down the audio.

One other thing to check... are some shows 29.97 / 59.94 Hz and some 
shows 30/60 Hz?  I've read that networks plan to transition to 30/60 Hz 
once the analog NTSC stations are off the air; maybe some shows are 
being produced that way now?  If so, Myth needs a way to select a video 
mode with the proper refresh rate added to its capability to pick one 
with the proper resolution.

-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 256 bytes
Desc: OpenPGP digital signature
Url : http://mythtv.org/pipermail/mythtv-users/attachments/20041214/c544b1e1/signature.pgp

More information about the mythtv-users mailing list