[mythtv-users] Jerky panning all cards and resolutions. Thoughts on where to look?

William Munson william_munson at bellsouth.net
Tue May 15 10:11:20 UTC 2007

Ben Lancaster wrote:
>> Since day one I have noticed that panning scenes have a distinct 
>> "gallop". This is independent of video mode, resolution, signal source, 
>> real time setting or rendering method. On about a 1/2 to 1 second cycle 
>> the pan will speed up and slow down in a repeating pattern. Nothing I 
>> have tried has fixed the problem. I dont think this is related to cpu 
>> usage as it happens even when playing SD which results in an average 
>> usage of about 12%. HD playback is 50-55% usage. The box is a dedicated 
>> myth system with a 2.8GHz AthlonXP mobile with plenty of memory. Signal 
>> sources are 2 pvr-250's and a HDHR. Video card is a NVidia FX5200 using 
>> the standard VGA output to drive my HD monitor. This has happened since 
>> myth 0.19 and is present in 0.20, 0.20.1 and SVN so I doubt its myth 
>> itself. Any suggestions on what else to check?
> Are you by any chance watching 50Hz/25Hz source over 60Hz VGA? If you're 
> in the UK/Australia then this is probably the case - the problem is 
> caused by mythtv's framerate interpolation (adding the extra 10 frames 
> to make it up to 60) as it would seem it just duplicates frames, hence 
> the jerkiness
> The only solution is to go for DVI->HDMI and set it to 50Hz. I tried 
> component on my Nvidia 6200 card, but from what I read Nvidia have 
> "locked" the component output to 60Hz, so you get the same problem.
> Very annoying, I know. This is one thing that MCE has over MythTV - 50Hz 
> video plays flawlessly smooth over a 60Hz link!
> Ben

Thanks Ben. Unfortunately its not the issue. I am in the usa and my 
modeline is 59.95 hz. The tv is very picky about its signal and that is 
the only value that will work. Any other ideas?


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