[FFmpeg-user] Note to document maintainer

[Tim Nicholson]

On 24/03/12 17:40, 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?

the frame rate is specified by the -r, so  -r 1 => 1fps.

Not sure how well this handles fractional framerates but give it a try.


> 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
> 
> 

It is almost impossible to cover every nuance of syntax difference between
different OS's and different shells. In particular quoting, and escaping can be
particularly thorny. I believe the documentation is, by and large, consistent
with bash, and reference is made to the above issues. So for those using other
shells you just need to learn the differences.


-- 
Tim