[mythtv-users] Re: Mythtv, nvidia and DVI mystery

[Brad Templeton]

On Fri, Mar 04, 2005 at 03:54:56PM -0600, Neil wrote:
> Brad Templeton writes: 
> 
> 
> It's totally different from interlace artifacts. Here is an example of how 
> I am understanding on what you meant by interlaced artifacts - 
> http://neuron2.net/LVG/inthead.jpg Please correct me if I am wrong. 

Yes, those are interlace artifacts.  These only occur on moving objects,
however, not on stationary ones.   Smart deinterlacers know the difference
between moving objects and stationary ones, and deinterlace differently.

If your TV is native 720p, like many Mitsubishis, the main reason to run
1080i video at 1080i is that the TV probaly has a high quality hardware
deinterlacer in it you would then take advantage of.  It is carefully
tuned to reduce 1080i to your native resolution.

If your software will do it better than the TV, better to run at 720p and
have myth do it.  But all myth offers are things like linear blend (which
blurs moving objects a lot) and bob (which works well with some artifacts
and some shimmer on certain things.)

> If so, then, it's different. I only see mine in just 1 line but random Y 
> coordinates. It only happens on very fast moving objects. Here is an 
> example. Like in the program American Idol, I don't know if you have that 
> program. During a presentation of a performer, behind her is a large flat 

Unfortunately, we do have it, but I don't record it.

But American Idol is on Fox, and Fox transmits at  720p, not 1080i.

You definitely should not be taking a 720p signal and running it to your
TV at 1080i, especially if your TV is not native 1080 lines.   If you
have a native 720 line TV like my Mitsubishi, avoid this like the plague.
Use RANDR.


> Overscan? I guess, overscan only has something to do with picture being 
> larger than my hdtv. Fortunately, mythfrontend comes with X&Y offsets, size 
> that we can tweak. And with that, I am able to size my watching to almost 
> 99% of my hdtv screen.
The problem I see with overscan is that I don't know what happens when
you send a 1080i signal in that is not being downscaled at the ratio
the TV is tuned for on other 1080i signals it gets, like from the tuner.