[FFmpeg-trac] #9454(undetermined:new): sendcmd w/h to crop appears broken

FFmpeg trac at avcodec.org
Fri Oct 15 09:31:59 EEST 2021

#9454: sendcmd w/h to crop appears broken
             Reporter:  Jozef Chutka  |                     Type:  defect
               Status:  new           |                 Priority:  normal
            Component:  undetermined  |                  Version:  4.3.2
             Keywords:  crop sendcmd  |               Blocked By:
             Blocking:                |  Reproduced by developer:  0
Analyzed by developer:  0             |
 Summary of the bug:

 Using ffmpeg 4.4, I am trying to crop video and actually animate the width
 in time using sendcmd + crop. This however leaves artefacts (either green
 color or the video texture being repainted repeatedly
 horizontally/vertically) rendered outside of the cropped area.

 How to reproduce:

 ffmpeg -f lavfi -i color=color=0xff0000:size=1280x720:rate=25
 -filter_complex_script filter.txt -map [v] -t 4 out.mp4 -y


 movie=video.mp4,sendcmd=c='0 [expr] crop w (N*10)+10',crop[v];

 The code above should animate cropped width from small to large over time.
 However it seems that rendering appears broken and texture is somehow
 repeated even outside crop area.

 It would be also nice if one could access iw/ih when animating crop size
 either by:
 1. crop w/h can evaluated per frame just like x/y is (without using
 sendcmd at all)
 2. sendcmd to recognize iw/ih which is probably hard to do
Ticket URL: <https://trac.ffmpeg.org/ticket/9454>
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