[mythtv-users] mythfrontend is shearing video playback

[Brad DerManouelian]

On Mar 18, 2008, at 11:24 PM, John and Holly Klug wrote:

> Steve Smith wrote:
>> John,
>>
>> 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.

> It starts with a misleading statement that this applies to people with
> modern non-interlaced displays like LCD or plasma.

"Modern" is a relative term. I don't think it's misleading.  
Comparatively speaking, anything in the last 10 years I would consider  
a "modern" display.

> I tried SSE first, since it sounded the best bang with low work, and
> 1080i recordings no longer show any shearing at 1080i.  I may try Bob
> later, but I would like to move on to 720p next.
>
> 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. Either that or your display doesn't  
interpret the 720p resolution very well. I've heard about this on  
plasma displays, but I have an LCD that doesn't require a modeline so  
I don't know exactly what the effect looks like.

> 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. It's really annoying and not much I can do about it.  
Luckily it's only Pee Wee's Playhouse Christmas Special so the need to  
watch is low.

> Just for kicks I tried all four of these EDID values to no avail:
>
> (II) NVIDIA(0): "1920x1080_60i"      : 1920 x 1080 @  60.1 Hz  
> Interlace
> (from: EDID)
> (II) NVIDIA(0): "1920x1080_60i_0"    : 1920 x 1080 @ 59.94/60 Hz
> (CEA-861B Format 5) (from: EDID)
> (II) NVIDIA(0): "1280x720_60"        : 1280 x  720 @  60.0 Hz   
> (from: EDID)
> (II) NVIDIA(0): "1280x720_60_0"      : 1280 x  720 @ 59.94/60 Hz
> (CEA-861B Format 4) (from: EDID)

You might need to specify a modeline for your display. I would do some  
research on that and see if you get closer to what you need.


-Brad