ffmpeg: crop then scale does not work I want to crop black border, then scale to video to 1280x720, however, the following command does not work，crop works well, but scale has no effect:

ffmpeg -i input.mp4 -filter_complex '[0:v]crop=1424:720:0:40[c0];[c0]scale=1280:720[bg]' -map '[bg]' -map 0:a -pix_fmt yuv420p output.mp4
The scale filter adjusts the aspect ratio, so that the display ratio remains the same. Assuming you don't want that.

Use

ffmpeg -i input.mp4 -vf crop=1424:720:0:40,scale=1280:720,setsar=1 -c:a copy output.mp4