[MPlayer-users] Inverse telecine

[Sean R. Lynch]

I noticed that in earlier archives on this list people were referring to
the 3:2 pulldown that's done in the decoder on NTSC DVDs encoded at
23.976 frames per second "telecine". DVDs encoded this way present no
problem for progressive encoding. However, the majority of NTSC DVDs
encoded from 24 fps content are actually encoded at 29.97 fps and the
3:2 pulldown is done in the encoder. 

Transcode has had a filter called "32drop" for a while that is supposed
to handle reconstructing the original progressive frames from telecined
fields. However, it doesn't work very well. Recently, someone ported or
rewrote the "decomb" filter from AVISynth to transcode. This consists of
a filter called "ivtc" which reconstructs progressive frames but leaves
duplicates, followed by "decimate" which drops the duplicate frames. 

<http://www.inmatrix.com/articles/ivtcsynth1.shtml> 
<http://sauron.mordor.net/dgraft/telecide.html> 

I've tested ivtc,decimate on telecined anime content and it works great.
Several interlaced frames did make it through, but not enough for me to
really care about using a postprocessing filter with it. This generally
happens whenever there's a change in the pulldown pattern. If you look
at yuvkineco that comes with mjpegtools, it works exactly the same way
*and* it has a postprocessing deinterlace filter to deinterlace frames
it misses that runs only when over 1% of the pixels get deinterlaced by
it. 

After using mencoder a bit, it looks like it's much easier to use and
quite a bit faster than transcode, and it seems a bit less buggy. I have
to use mencoder anyway to extract VobSub subtitles and to get a
reasonable estimate of encoding bitrate to burn to CD, so I would love
to be able to use mencoder for the main encoding process on telecined
DVDs. Is anyone working on porting/writing an inverse telecine filter
for mencoder? I'm kind of surprised that everybody's been looking to
Windows programs like VirtualDub and AVISynth for this sort of thing,
since yuvkineco's been part of mjpegtools for a while. 



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