I was playing around with some
ffmpeg filters, like cropping, scaling and overlays and I was tired of waiting for the video to be fully re-encoded in order to see the changes.
ffmpeg -i video.mp4 -vf "crop=in_w:in_h/2:0:0" -c:a copy output.mp4
I'm glad that this is not a problem because you can use
ffplay to preview the changes instantly without having to wait:
ffplay -i video.mp4 -vf "crop=in_w:in_h/2:0:0"