Some ffmpeg commands

Crop:

ffmpeg -i in.mp4 -vf "crop=out_w:out_h:x:y" out.mp4

• out_w, out_h – width/height of the output rectangle (e.g. 850/2)
• (x,y) – top left corner for the output rectangle
• in_w, in_h – input width/height (e.g. in_w-40, in_w/2)

docs reference

Trim:

ffmpeg -i in.mp4 -ss hh:mm:ss -to hh:mm:ss out.mp4

• -ss – starting timestamp
• -to – ending timestamp
• -t – duration

Mute:

ffmpeg -i in.mp4 -an out.mp4

Adjust audio:

ffmpeg -i in.mp4 -af "volume=0.1" out.mp4

• -af filter audio stream

Add audio to video:

ffmpeg -i in.mp4 -i audio.mp3 -filter_complex "amix=inputs=2:duration=first" -c:v copy out.mp4

• loop audio: -stream_loop -1 -i background.wav

amix source another

Format:

• -f rawvideo to force input/output file format (usually auto-determined by file extension)

• -pix_fmt rgb24 per Wikipedia, the format in which the image data output is represented

• List of all formats from ffmpeg -formats
• List of all pixel formats from ffmpeg -pix_fmts

General:

• -c copy for no re-encoding
• -preset veryfast|ultrafast|... for faster compression (tradeoff size/quality) list
• ffplay to play a video (mostly used to test ffmpeg transformations)
• ffmpeg -i in.mp4 -filter_complex "select=bitor(gt(scene\,0.5)\,eq(n\,0))" -vsync drop "frames/%04d.jpg" export unique frames? (magick in.mp4[0] for single frame) (src)