[FFmpeg-devel] full swscale relicensing to LGPL

Ivan Schreter schreter
Sat Mar 28 23:22:29 CET 2009

Michael Niedermayer wrote:
> [...]
>> deficiencies regarding frame rate detection in MPEG-TS/PS streams (and 
>> possibly other containers). For instance, 25 fps *interlaced* H.264 coded 
>> as field pictures (50 fields per second) gets double frame rate (50Hz 
>> instead of 25Hz) and produces a full frame in decode_picture only for each 
>> second tick (i.e., actual full frame rate is 25Hz). This is handled 
>> correctly by ffplay and ffmpeg, simply by copying the frame and dropping it 
>> again when encoding back to 25 fps, but may confuse other programs using 
>> lavf/lavc.
> copying & droping? what makes you belive anything is copying and droping
> frames?
Well, maybe ffmpeg printing 1 dup in verbose mode for each input frame 
when converting 25 fps interlaced video? The resulting video is 50 fps 
instead of 25 fps and contains each frame twice => it's obviously 
copying it.

When specified frame rate explicitly with -r 25, then it produces 
correct video with 25 fps. If internally copying & dropping is done or 
not, I'm not sure.

Anyway, detection of container frame rate is wrong (see also my other 



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