[mythtv-users] mythfrontend is shearing video playback

[Michael T. Dean]

On 03/19/2008 10:01 AM, Brad DerManouelian wrote:
> On Mar 18, 2008, at 11:24 PM, John and Holly Klug wrote:
>> Steve Smith wrote:
>>     
>>> Your description of the symptoms is exactly what you get if you NEED
>>> TO TURN DEINTERLACING ON!
>> Eureka:
>> http://www.mythtv.org/wiki/index.php/Deinterlacing
>>     
>
> Wow! If only someone had pointed out deinterlacing to you as the  
> solution at the start of this thread, it would have saved you the time  
> of finding that out for yourself.
>   

Heh.

>> Deinterlacing seem to have no affect on 720P recordings, and bright
>> flashes of light, change of scenery, panning, or zooming result in
>> visible lines on the screen at both 1080i and 720p X mode settings.
>>     
> Deinterlacing is not applied to 720p recordings. Note the "p". It's  
> progressive - the opposite of interlaced. If you are seeing problems  
> viewing progressive content then I would say your modeline or video  
> driver isn't set up correctly.

Or, the broadcaster took interlaced content and transcoded it to a 720p 
format without doing proper telecining or deinterlacing.  I see this a lot.

>> I notice the same line problem in an old fashioned encrypted  
>> commercial
>> DVD recording, presumably at 480p?.  At least that is what my set says
>> when I play it from my standalone DVD player.  I can back up, play it
>> again, and see the same problem over and over again.  Needless to say,
>> these problems don't occur when played from my standalone DVD player  
>> or
>> from the RGB output of the same system to a normal monitor.  If I  
>> try to
>> deinterlace a DVD movie with VLC, the movie is closed.
>>     
> Right. If it's encoded at 480p then you can't deinterlace. It's  
> progressive. I have the same problem with some older DVD's. They took  
> 408i content and stuck it on a 480p DVD and didn't bother to make it  
> progressive.

I.e. they didn't properly telecine/deint.  It's much more common on 
DVD's than on broadcast content (though it's not exactly rare on 
broadcast content).

Mike