[FFmpeg-user] Using ffmpeg to blur moving objects

[Paul B Mahol]

On 10/31/16, Boris T <boris.t.richard at gmail.com> wrote:
> Hello,
>
> I'm using ffmpeg to blur moving objects in videos with a command similar to
> this one:
>
> ffmpeg -i "input.mp4" -filter_complex_script "myscript.txt" -map
> "[step0_overlay]" -f MP4 -c:v libx264 -x264opts
> keyint=15:min-keyint=15:scenecut=-1  -movflags faststart -y "output.mp4"
>
> myscript.txt contents:
>
> [0:v]crop=160.00:160.00:94.40:96.00,boxblur=luma_radius=min(10\,min(w\,h)/2):chroma_radius=min(10\,min(cw\,ch)/2)[step0];[0:v][step0]overlay=94.400:96.00:repeatlast=0:enable='between(t,0.073,7.55839409433962)'[step0_overlay];
>
> This does the job fine, but since I'm blurring moving objects, I end up
> with multiple crop and overlay filters enabled for fractions of seconds.
> For a 2-minute video with a constantly moving object I can end up with 2000
> of these crop-overlay steps, and the more overlay steps I have, the slower
> the processing gets (less than a frame per second) Is there a better,
> faster approach to this problem?
>
> I've tried using sendcmd to modify and move the blurred overlay on the fly
> (and presumably avoid having to keep multiple overlays in the filter graph)
> however I ended up with a blurred box inside the original blurred box.
>
> Any input on this problem would be greatly appreciated!
>
> Boris
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Short story: AFAIK it is not currently possible to track specific
moving object with FFmpeg.