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