[MPlayer-dev-eng] [PATCH] Convolution deinterlacer

[D Richard Felker III]

On Sat, Mar 29, 2003 at 12:47:36AM -0500, James Bostick Crowson wrote:
> This filter is a deinterlacer which tries to blur still images by a
> minimal amount while still doing a good job of removing interlacing
> artifacts.  In my estimation the visual quality on anime is better than
> all of MPlayer's other deinterlacers.  It is used by "-vop pp=cd".

Hmm, anime is never really interlaced (that would require drawing the
frames at 60 fps which would be prohibitively expensive); instead,
it's telecined. So, if you can correctly detect which frames are which
in the telecine sequence, you can 'losslessly' reverse the process and
get 24fps non-interlaced frames. However, detecting which frames are
which seems to get very complicated. The "detc" filter I wrote is
supposed to do this, but it still has many problems...

> There are several problems with this filter currently:
> 
> 1) It is for MPlayer 0.90rc5.  I don't know where the postprocessing code
> has gone to in the CVS version - sorry.

It got moved to libavcodec/ffmpeg cvs.

> 2) It shifts the luma plane up two lines.  I think this is OK as long as
> the chroma plane is shifted up one line too.  In testing I used "-vop
> scale,pp=cd -ssf cvs=1".  It doesn't do it in the filter since I don't
> know how.

Hmm... If you apply the filter to both luma and chroma planes (which
is necessary -- both are interlaced!) then shouldn't it also shift the
chroma up 2 lines?

> 3) It is C only, as I am not an MMX guru.

No problem -- someone else can write the MMX later.

> 4) It suffers from clipping problems that manifest as spurious white or
> black dots.  I don't know how to fix this.

That's because your convolution function sums to 12 but you only
divide by 8!

> Because of the number of problems with this patch that I don't know how to
> fix, I understand if it's not applied, but I would appreciate if someone
> were to go through and fix them, since I believe the quality really is
> better in many cases.

I think it should be applied, after these problems are fixed... Like I
said, I don't think it's useful for anime, but it might be very nice
for real interlaced material. The other deinterlacers rather suck...

Rich