[MPlayer-users] Re: inverse telecine... not

[Brian Craft]

On Wed, Feb 19, 2003 at 05:37:53PM -0500, D Richard Felker III wrote:
> I think I'll go ahead and commit it to CVS soon, but with the
> understanding that it might change a good bit over the next few weeks,
> including in ways that make it incompatible with old options syntax,
> etc. That way users can actually test it and see if it works.

Very cool. I'll be curious to see how you approached it.

Reading up on it a bit, it's significantly more complex than I imagined. You
can't expect the 3-2 pattern to be consistent throughout the entire video (for
various reasons, including the possibility that the stream was edited after
being telecined), so resyncing has to be done continuously. 

Apparently sync accuracy is a differentiating feature of hardware devices that
do inverse telecine -- the poorer implementations may let a few interlaced
frames through before resyncing, if there is a change in the pattern.

Seems like a hard thing to do quickly in software, since there are no markers
on the interlaced frames -- the player has to "look" at the frame and decide
if it's interlaced.

I was thinking it might be possible to make a telecine table of a file prior to
playback, in the event that the pattern changed. Then the player wouldn't have
to detect it on-the-fly, but would just look up the pattern changes based on
frame count.

b.c.