[mythtv-users] Interlacing [was: Pvr250 issues - any suggestions?]

[Gert van der Knokke]

Nick Craig-Wood wrote:

>On Sat, Apr 03, 2004 at 12:54:19PM +0200, Henk Poley wrote:
>  
>
>>I've thought about this before, why doesn't MythTV keep track of a video 
>>source is interlaced or not. So you can specify per recording/transcoding 
>>profile (should also be seen as a video source) and front-end if you want to 
>>deinterlace, without the possibility of deinterlacing twice which would 
>>introduce more artifacts.
>>    
>>
>
>Or alternatively why doesn't mythtv display interlaced video the way
>it was intended to be displayed?
>
>Mythtv is currently displaying frames at 25 (PAL), 30 (NTSC) Hz which
>look like this
>  
>
Yep, but your monitor isn't... Since most monitors  run at 70-100 Hz you 
never get this right and you'll end up having the tearing effect during 
motion... Unless you use TV-Out (which should do  50/60 Hz interlaced) 
and you can get the  the right lines at the right place  at the right 
time  :-)

However most of the TV-out cards can handle non-interlaced output only.

I mentioned this before on the list since this is the same problem with 
100 Hz TV-sets, if you have a chance to view some next to each other 
then try to view a channel with a ticker line and you can immediately 
see the difference between good and bad 100 Hz sets..
As a Audio/Video repair man I know the major brands like Philips Sony 
etc. have done enormous research in getting this right. (and so far only 
Philips has got it just right with their latest Natural Motion sets by 
generating intermediate frames) Same problem with LCD and Plasma sets, 
since LCD is by nature progressive scan.
Other problems arise with movies since their framerate differ even more 
from 25/50/60/100 ...

Trying to display computer output (being CVBS/S-VHS or SVGA) on a 100 Hz 
TV set is asking for trouble unless you can sync the output to the 
framerate of the TV..

Gert