FFmpeg tips

Here are a few commands for FFmpeg that were useful for me.

The help page for all parameters is here.

A nice tool that uses FFmpeg is Handbrake.

Get some info about a file

ffmpeg -i video.mp4

Parameters:

• ffmpeg is the ffmpeg command :p
• -i video.mp4 specifies the input file

Extract the audio part of a video

ffmpeg -i video.mp4 -vn -acodec copy audio.m4a

Parameters:

• -vn disables the video
• -acodec copy allows to copy the audio stream without touching it
• audio.m4a is the output file

Convert an audio file to another format

ffmpeg -i audio.m4a -acodec libmp3lame -ac 0 -ab 320k audio.mp3

Parameters:

• -acodec libmp3lame allows to use the lame mp3 library for conversion
• -ac 2 sets the number of channels
• -ab 320k sets the bitrate

Of course, the previous command and this one can be merged for a 1 step audio extraction & conversion.

Crop a video

ffmpeg -i video.mp4 -vf "crop=760:430:520:0" output.mp4

Parameters:

• -vf "crop=760:430:520:0" applies a filter on the video. The values for the "crop" are: width:height:left:top.

Pro-tip: use ffplay to preview the cropped area !

ffplay -i video.mp4 -vf "crop=760:430:520:0"

Create a gif from a video

ffmpeg -i dauphin.mp4 -r 10 dauphin.gif

Parameters:

• -r 10 sets the framerate

Resize a video

ffmpeg -i cut.mp4 -vf "scale=500:-1" -c:a copy resized.mp4

Parameters:

• -vf "scale=500:-1 sets the target size: 500px in width, -1 tells ffmpeg to automagically calculate the height.
• -c:a copy copies the audio stream. You can use -an to skip the audio track.

Rotate a video

ffmpeg -i video.mp4 -vfilters "rotate=90" -c:a copy out.mp4

Parameters:

• -vfilters "rotate=90" sets the rotation angle.
• -c:a copy copies the audio stream. You can use -an to skip the audio track.