[FFmpeg-devel] Scale, Rotate, Translate Matrix Op.

Mina Nagy Zaki mnzaki at gmail.com
Mon Jun 13 01:40:36 CEST 2011

On Monday 13 June 2011 03:26:15 Joshua Grauman wrote:
> Unfortunately, I can't get the perspective filter to do a rotate. Does
> anyone know if it is capable of doing them? I calculated the 4 coordinates
> based on a rotated rectangle, so I thought it should work.

Have you tried the transpose filter? it does 90 degree rotations.
ffmpeg -i input.avi -vf transpose=1
argument should be between 0 and 3.

There are also vflip and hflip filters.

> Also, on another note. The patch I found to do matrix transformations
> isn't a filter as far as I can tell from looking at the code. It looks
> like it's just a function to do the actual matrix transformation. How hard
> would it be to write a filter to make use of this code? Any stub filters I
> can look at? Anyone willing to give me a hand at doing it? Thanks!

Writing a filter shouldn't be too hard, look at libavfilter/vf_transpose.c for 
example. All callbacks are well documented in libavfilter/avfilter.h


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