Video Manipulation

work in progress

by FND

cf. Image Manipulation

Reduce File Size

$ ffmpeg -i input.mp4 -vcodec libx264 -crf 20 output.mp4

Vary the CRF between around 18 and 24 – the lower, the higher the bitrate.

or

$ ffmpeg -i input.mp4 -b 1000000 output.mp4

source: How can I reduce a video’s size with ffmpeg?

Cut

$ ffmpeg -i input.mp4 -ss 00:00:10 -t 60 output.mp4

This will skip the first 10 seconds retain 60 seconds after that.

Crop

$ ffprobe -v error -select_streams v:0 -show_entries stream=width,height \
        -of compact input.mp4
$ ffmpeg -i input.mp4 -filter:v "crop=$width:$height:$x:$y" output.mp4

This reduces the visible area to the given dimensions (e.g. "crop=640:360:320:180").

source: How to Crop and Resize a Video Using FFmpeg

Rescale

$ ffmpeg … -vf scale=800:-1 …

This will set the width to 800 pixels, calculating the height of the output image according to the input’s aspect ratio.

Split

$ ffmpeg -v quiet -y -i input.mp4 \
        -vcodec copy -acodec copy -ss 00:00:00 -t 00:45:00 -sn output1.mp4 \
        -vcodec copy -acodec copy -ss 00:45:00 -t 01:30:00 -sn output2.mp4

NB: This might result in audio being out of sync.

Convert Movie to GIF

$ ffmpeg -i input.mp4 -s 800x450 -r 14 -f gif output.gif

-ss 1.25 additionally skips the first 1.25 seconds