Dynamically Change Video Crop Width, Height, X And Y Using Ffmpeg

I am doing object detection on a video and so far I've gotten the coordinates of the objects in the video. now I want to crop the video frame by frame given the location/coordinate

Solution 1:

Use the sendcmd filter.

1. Make commands.txt:

   0    crop w 148,
        crop h 254,
        crop x 925,
        crop y 108;
   
   0.04 crop w 142,
        crop h 252,
        crop x 927,
        crop y 107;
   
   0.08 crop w 147,
        crop h 258,
        crop x 928,
        crop y 102;
   

   • The text does not have to be formatted exactly as above. I added line breaks for readability. You can place each timestamp on its own line if you prefer.
   • sendcmd works with timestamps, not frame numbers. This example shows frames 1-3 and assumes a frame rate of 25 (1/25 = 0.04).
   • Not all filters can use sendcmd (or the audio version asendcmd). See output of ffmpeg -filters. If the filter supports (a)sendcmd it will have a T preceding the filter name in the list.
   • Not all filter options can be used with sendcmd. See FFmpeg Filters Documentation and look for "Commands".

2. Run ffmpeg:

   ffmpeg -i input.mp4 -filter_complex "[0:v]sendcmd=f=commands.txt,crop" output_%03d.png