[Ffmpeg-devel] Patch: speed conversion

Michael Niedermayer michaelni
Fri Jul 22 23:53:23 CEST 2005


On Friday 22 July 2005 20:52, Jules wrote:
> 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.  

this is a pretty dirty hack, not to mention the printfs would break 
input/output over stdin/out


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