identify video delegate ffmpeg parameter correction

[fgro]

Hi folks,

when you identify a video file imagmagick delegates to ffmpeg.

The current delegates.xml entry reads:

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<delegate decode="mpeg:decode" command=""ffmpeg" -v -1 -vframes %S -i "%i" -vcodec pam -an -f rawvideo -y "%u.pam" 2> "%Z""/>

However, the -vframes parameter must come after the input file parameter, otherwise it will be ignored and every frame will be processed when calling identify on a specific frame such as

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identify video.mp4[0]

This may lead to heavy cpu load as well as tmp folders quickly filling up with data.

Hence, the correct delegates.xml entry should read something like this:

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<delegate decode="mpeg:decode" command=""ffmpeg" -v -1 -i "%i" -vframes %S -vcodec pam -an -f rawvideo -y "%u.pam" 2> "%Z""/>

Please note this fix is for the latest version of ffmpeg. On older ffmpeg versions (i.e. 0.7.8 ) the misbehaviour does not seem to occour.

For reference, here the according ffmpeg bug:
https://ffmpeg.org/trac/ffmpeg/ticket/898


Happy video identifying

[magick]

Thanks, we'll get the patch into the next point release of ImageMagick.