[mythtv-users] deinterlacing

Brad DerManouelian myth at dermanouelian.com
Sat Mar 8 04:52:58 UTC 2008


On Mar 7, 2008, at 7:14 PM, Robert Johnston wrote:

> On Fri, Mar 7, 2008 at 6:25 PM, Kevin Bailey
> <ke-myth at retriever.dyndns.org> wrote:
>> On Fri, Mar 07, 2008 at 02:56:10PM -0800, David Brodbeck wrote:
>>>
>>>   Rule of thumb: If it's an ordinary, standard-definition TV, it's
>>>   interlaced.  Otherwise, it's almost certainly progressive.   
>>> There are
>>>   exceptions but if you have a piece of equipment that doesn't fit  
>>> this
>>>   rule, you probably already know it. :)
>>
>> Here's something I never really understood: I'm running
>> myth into a TV over S-video, and some channels had a
>> "comb" effect on moving objects until I turned on
>> de-interlacing. If a TV is interlaced, I'm confused
>> why this setting was necessary. I have the suspicion
>> that something else is going on, as though in
>> translating from 1080i or whatever to 480i, something
>> gets changed. Or is there an obvious explanation for
>> this ?
>
> Generally, your computer's display will be Progressive (640x480p).
> However, the video card will be (At the output stage) converting that
> progressive image to an interlaced picture.
>
> Unless the video card has specifically stated it has detected a TV and
> is outputting to it (Which will mean 640x480i), Then the problem could
> be that the interlaced fields in the recorded signal are not in sync
> with the interlaced fields being output, which could (would)
> exacerbate the situation.

I think the best explanation is that S-Video will likely be  
progressive (480p - like a DVD) unless you go through some sort of  
extra effort to make it do interlaced (480i - like a standard- 
definition broadcast signal). If you're seeing interlace artifacts,  
you're outputting progressive.



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