[Ffmpeg-devel] Patch: speed conversion

Jules jules
Fri Jul 22 20:52:29 CEST 2005

The attached patch adds a command line option to 'ffmpeg' that allows 
you to alter the playback speed of a video.  E.g.:

ffmpeg -i input -spc 2:1 output  
    (produces a video that is the input slowed down by a factor of 2)

ffmpeg -i input -spc 23976:25000 -r 25 output
    (converts an NTSC-film input to a PAL output, speeding up
     playback by about 4%)

It achieves this result by overriding the time base and sample rate of 
the input files, to make them appear to have been recorded at a 
different speed.  I'm not sure how it will interact with subtitles, as I 
don't have any subtitled videos here to test with.

Hope this is useful in some way.


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