[MPlayer-users] 60p -> 24p conversion for ATSC

[Rich Felker]

On Thu, Feb 09, 2006 at 02:40:31PM -0800, rob pfile wrote:
> some time ago i posted about this topic, and Rich Felker was kind 
> enough to reply. he mentioned that there was a hack using vf_tinterlace 
> to do frame decimation of 24p material that's had frames duplicated for 
> broadcast as 60p ATSC. i wasnt able to find any mention of this 
> anywhere in the archives, so if someone out there can describe this 
> hack, i'd be interested in hearing about it.

The basic idea is:

-vf tinterlace,pullup

Strictly speaking this is not correct since the pairs of frames
interleaved together are actual frames, not fields offset by half a
line from each other. However, at HDTV resolution this distinction
doesn't mean a lot.

The above filter chain will leave you with incorrectly double-height
video. You can scale back down afterwards. There are tricks using
nearest-neighbor resampling with the scale filter to get the exact
right behavior and compensate for the incorrect fake interlacing that
tinterlace makes, but I wouldn't suggest trying such things unless you
have a problem with the output, since you're likely to make it worse
if you don't understand the repercussions.

Rich