[MPlayer-dev-eng] key frame extractor / vo_jpeg use YV12 instead of RGB patch

[Compn]

On Thu, 15 Mar 2007 22:14:26 +0100, 
Andreas Krebs scribed:

> hi all,
> 
> I was looking for a program to extract relevant key frames from a
> video for creating a web page index. since I didn't find a program I
> liked, I decided to write a video output driver for mplayer to do
> this. 

i think gallery does this ? thumbnail html from video using ffmpeg or
mplayer.

> as a starting point I decided to use vo_jpeg.c since it already takes
> care of saving the frames as jpeg. so in a first step I added a new
> parameter 'framedist' to prevent vo_jpeg from saving every frame.

-sstep or -vf framestep will do same thing also -frames 10 to only
output 10 jpegs...

> working under all conditions. e.g. my patch expects that a slice in
> YV12 is always 16 pixel high and padded to match the jpeglib
> requirements (for all my test videos this seemed to be the case).

this is possibly a problem, altho i cant remember testing vo jpeg
against non /16 pixel video..

> --
> Andreas
> 
> 
> PS: if anybody has a good algorithm for calculating image
> similarities (for the key frame selection) please let me know.

the motion estimation stuff would help... also there is 
-vf blackframe for detecting black frames

-compn