[FFmpeg-user] extract frames every n frames

[francesco piasentini]

Thanks Moritz!
it worked out very well:

.\ffmpeg -i input.wmv -ss 00:00:12.000 -vf select='not(mod(n\,7))' -vsync
vfr -compression_algo raw -pix_fmt rgb24 output.tiff -hide_banner

is there the possibility to have a grayscale 8bit output?

best wishes

f


Il giorno gio 25 apr 2019 alle ore 00:57 Moritz Barsnick <barsnick at gmx.net>
ha scritto:

> Hi Francesco,
>
> On Wed, Apr 24, 2019 at 16:14:56 +0200, Francesco Piasentini wrote:
> > I need to extract frames every n frames.
> > Is there an option in ffmpeg?
>
> Sure. There's the "select" filter, which can take any kind of complex
> expression. Your requirement is even documented among the examples:
>
> https://ffmpeg.org/ffmpeg-filters.html#select_002c-aselect
>
> Every 100th frame:
> $ ffmpeg -i input -vf select='not(mod(n\,100))' output
>
> (Note that this will usually not speed up a video, because the
> timestamps are retained.)
>
> If the output muxer decides to force the same framerate as the input,
> and thereby duplicates your extracted frames, you can avoid that by
> using the "-vsync vfr" option. It might depend on your use case. Try
> with the above command first. :)
>
> Moritz
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