[FFmpeg-user] Note to document maintainer

Donald McLachlan Donald.McLachlan at crc.ca
Mon Mar 26 15:13:22 CEST 2012

On 24/03/2012 1:40 PM, Steve M. Fabac, Jr. wrote:
> As a newbie I tried the following example:
> The following example shows how to use ffmpeg for creating
> a sequence of files ‘img-001.jpeg’, ‘img-002.jpeg’, ...,
> taking one image every second from the input video:
>   ffmpeg -i in.avi -vsync 1 -r 1 -f image2 'img-%03d.jpeg'
> So what's the change/addition to create an image every two seconds?
> Every three seconds?  The needed switch may be buried in
> the overall documentation. Having it in the "section 9.3 image 2"
> would save newbie's a lot of searching.
> Also, the single quotes above fail under Windows XP and the correct
> command is: ffmpeg -i in.avi -vsync 1 -r 1 -f image2 img-%03d.jpeg

I have recently used -f image2 to extract a video to a series of pegs 
and it works just fine.

In the example you provided, "-r 1" sets the output frame rate to be 1 
frame per second.  Did you try "-r 0.5" for one frame every 2 seconds?

If your video is 30 frames/sec I guess you could extract all the frames 
and then hand pick the ones you want from the lot of them.

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