[FFmpeg-user] set image width only?

[lovelove]

lovelove wrote:
> 
> I don't really understand the difference between
> *-s 400x300*
> and
> *-vf "scale=400:300"*
> 

Aside from the difference from the -s parameter being unclear,
the -vf scale parameter you suggested to me somehow interferes with key
frame detection.

This extracts all key frames of a video as single images:
*ffmpeg.exe -i inputfile.avi -vf select="eq(pict_type\,PICT_TYPE_I)" -vsync
0 -f image2 outputfile.AVI-%03d.tif**

But when adding -vf scale, *ALL* images are extracted, not just keyframes:
*ffmpeg.exe -i inputfile.avi -vf select="eq(pict_type\,PICT_TYPE_I)" -vsync
0 -vf "scale=400:-1" -f image2 outputfile.AVI-%03d.tif**

What's going wrong? thank you.

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