[MPlayer-dev-eng] More on inverse telecine!

[D Richard Felker III]

On Mon, Apr 14, 2003 at 06:39:26AM -0500, Billy Biggs wrote:
> > >   No I just meant filter the input scanline with a low-pass filter
> > > before looking at absolte difference.  Like [1 4 6 4 1] before you do
> > > the abs.
> > 
> > Ah, hmm... This is fairly difficult to do without serious additional
> > computation, which would slow the process down even more. It could
> > have some benefits, but from a mathematical standpoint I don't think
> > you really get more info from the difference of the blurred lines than
> > the original difference before blurring. (I'd have to sit down and
> > work it out to be sure though...)
> 
>   It's not that hard.  Even a [1 1 1 1] filter can help.  I've used
> something like this successfully on YUY2 content (luma every second
> byte):
> 
>     ret = 0;
>     while( width-- ) {
>         unsigned int tmp1 = (cur[ 0 ] + cur[ 2 ] + cur[ 4 ] + cur[ 6 ])>>2;
>         unsigned int tmp2 = (old[ 0 ] + old[ 2 ] + old[ 4 ] + old[ 6 ])>>2;
>         tmp1  = (tmp1 - tmp2);
>         tmp1 *= tmp1;
>         tmp1 >>= 6;
>         ret += tmp1;
>         cur += 8;
>         old += 8;
>     }
>     return ret;
> 
>   Lots of improvement you could do there though.

Yes, but that ignores the fact that I'd need to do a whole block of
current and prev. frame at a time for processing, and the ugly
boundary conditions (what do you do on leftmost and rightmost pixels?)
etc.

> > Oh. I think this is more of a concern with broadcast tv, especially
> > with the horrible way chroma is carried on NTSC. As long as the source
> > material was edited only as composite video and/or with digital
> > methods, chroma should not mess up the luma.
> 
>   Sorry, but composite video is what messes it up, broadcast video is
> just a form of composite video, but with more noise.  Composite means
> you're mixing the luma and chroma on the same channel, and they will

Sorry!! My silly typo, I meant component video.

> conflict.  If you're going straight from a DVD, you just have to hope
> the DVD wasn't mastered from a composite format like LD or even VHS
> (hey, I've seen it!).  If you're capturing analog, make sure you capture
> over component, but just using S-Video can ensure your luma won't be too
> messed up (again, depending on the source).

If the material is telecined, it's probably originally movie content,
in which case I'm not interested in analog copies. :)

Rich