[MPlayer-users] Comparison of different deinterlace and denoise filters

[D Richard Felker III]

On Tue, Oct 21, 2003 at 09:59:57PM +0200, Matthias Wieser wrote:
> [Automatic answer: RTFM (read DOCS, FAQ), also read DOCS/bugreports.html]
> Am Freitag, 17. Oktober 2003 04:56 schrieb D Richard Felker III:
> 
> > > That may be the case with a bttv card.
> > > But I see _no_ chroma errors when I record only with outfmt=yuy2.
> > > Maybe thats because of the saa7134 driver.
> >
> > This is impossible by the nature of yuy2. It has 4:2:2 sampling.
> 
> 4:2:2 sampling gives chroma each line. Where's the problem? I record raw 
> video with chroma every line.

If you're recording raw video in 4:2:2, no problem. But if it's
converted to 4:2:0, you're in big trouble.

> > When
> > mencoder rescales the chroma to half height (4:2:0), it will be
> > ruined.
> 
> Doesn't (chroma) it first get deinterlaced and then rescaled (if you 
> export as mpg4 and not as png)?

If you're deinterlacing the 4:2:2 video and then converting to 4:2:0,
then yes, you'll get acceptable results. But if you want to keep the
interlacing (necessary if you don't want to throw away half the
quality) or use a deinterlacer/inversetelecine that only accepts yv12
(4:2:0) input, you must take care to do the conversion properly rather
than just letting auto-loaded vf_scale do its thing.

> > Do you know what error you're looking for?
> 
> I'm looking for those red(/blue) shadows (104,110 to 107,180 at http://
> home.knuut.de/MWieser_/vf_raw_ntv_8/raw_ntv_8_pp-ci.jpg). Is that right?

Yes, that's one of the many examples in that picture.

> > > > The only way to get around having to use
> > > > il=d:d,scale=format=vy12,il=i:i is if your card can natively
> > > > capture proper 4:2:0 video. (Unless you just want to capture at
> > > > half-height to begin with...)
> > >
> > > Which cards can do that?
> >
> > Probably anything but bttv, as long as you leave the default outfmt
> > (yv12).
> 
> You found those chroma errors on frames grabbed by my saa7134 card, too.
> 
> > However, you should check and make sure. Chroma plane should
> > be interlaced just like the luma.
> 
> They seem to be interlaced properly, but I'm not sure. I used gimp to zoom 
> into http://home.knuut.de/MWieser_/vf_raw_ntv_8/orig.jpg but could not 
> see anything suspect.

To see the error, you need to eliminate the luma channel and see if
the chroma is interlaced or not. Using the eq filter with contrast=0
can do this for you. I don't know any way to do it in gimp. If chroma
isn't interlaced, the your card probably suffers from the same bug as
bttv, :( or else you captured in yuy2 mode and let mencoder
auto-convert to yv12...

Rich