[mythtv-users] Deinterlacing Methods

Stroller linux.luser at myrealbox.com
Sun Jan 14 00:41:41 UTC 2007

Although I understand the difference between interlaced & progressive  
I don't really understand the implications of using each, and what  
problems may be caused by them. I therefore post this reply in the  
hope that someone else can correct my understanding. My comments &  
remarks should not be taken to be definitive.

On 13 Jan 2007, at 12:32, James Buckley wrote:
> ...
> My main problem was TV playback. I had my TV set on 'DVI (PC)', and  
> the EDID information passed let me get a picture with no overscan  
> whatsoever. The drawback with this was that it was dropping frames  
> (badly, don't know why, just TV is unwatchable). TV was jerky,  
> (especially the news tickers).

Is this not the "correct" way (or best way, perhaps?) to feed a TV  
which accepts such a signal? It's my understanding that such an image  
will be non-interlaced at full resolution, but that such an image  
will also require a lot of pixels–per-second. IE: you're effectively  
displaying an HD image (good!) and the best way to resolve this is  
throw more horse-power at the problem.

> Working Modelines: 1280x720p, at 50Hz with a little overscan
> ... I've found that I just can't match the quality of TV from my  
> freeview STB. I've gone through all the deinterlacing methods, and  
> the only one that has a decent framerate is BOB. However, I find  
> that BOB causes some parts of the picture to flicker. Normal scenes  
> look fine, but when digital boxes are drawn on the screen (such as  
> a news ticker), the horizontal edges between the box and the rest  
> of the picture will flicker slightly. It's a bit hard to explain,  
> but is most noticeable when a static picture is displayed. The  
> whole picture isn't jumping (like when there is a refresh rate  
> mismatch), just objects which are perfectly horizontal flicker (and  
> is bit annoying). I also oversize the picture slightly to get rid  
> of the top and bottom lines from flickering.

I think this is the nature of a progressive signal at 50hz.

I posted these links in another thread <http://www.gossamer- 
threads.com/lists/mythtv/users/244889#244889> a week ago:


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