FFmpeg cheat sheet

A list of useful commands for the ffmpeg command line tool.

Download FFmpeg: https://www.ffmpeg.org/download.html

Full documentation: https://www.ffmpeg.org/ffmpeg.html

Basic conversion

ffmpeg -i in.mp4 out.avi

Trimming

Without re-encoding:

ffmpeg -ss [start] -i in.mp4 -t [duration] -c copy out.mp4

• -ss specifies the start time, e.g. 00:01:23.000 or 83 (in seconds)
• -t specifies the duration of the clip (same format).
• Recent ffmpeg also has a flag to supply the end time with -to.
• -c copy copies the first video, audio, and subtitle bitstream from the input to the output file without re-encoding them. This won't harm the quality and make the command run within seconds.

With re-encoding:

If you leave out the -c copy option, ffmpeg will automatically re-encode the output video and audio according to the format you chose. For high quality video and audio, read the x264 Encoding Guide and the AAC Encoding Guide, respectively.

For example:

ffmpeg -ss [start] -i in.mp4 -t [duration] -c:v libx264 -c:a aac -strict experimental -b:a 128k out.mp4

Mux video and audio from another video

To copy the video from in0.mp4 and audio from in1.mp4:

ffmpeg -i in0.mp4 -i in1.mp4 -c copy -map 0:0 -map 1:1 -shortest out.mp4

• With -c copy the streams will be stream copied, not re-encoded, so there will be no quality loss. If you want to re-encode, see FFmpeg Wiki: H.264 Encoding Guide.
• The -shortest option will cause the output duration to match the duration of the shortest input stream.
• See the -map option documentation for more info.

Concat demuxer

First, make a text file.

file 'in1.mp4'
file 'in2.mp4'
file 'in3.mp4'
file 'in4.mp4'

Then, run ffmpeg:

ffmpeg -f concat -i list.txt -c copy out.mp4

Delay audio/video

Delay video by 3.84 seconds:

ffmpeg -i in.mp4 -itsoffset 3.84 -i in.mp4 -map 1:v -map 0:a -vcodec copy -acodec copy out.mp4

Delay audio by 3.84 seconds:

ffmpeg -i in.mp4 -itsoffset 3.84 -i in.mp4 -map 0:v -map 1:a -vcodec copy -acodec copy out.mp4

Burn subtitles

Use the libass library (make sure your ffmpeg install has the library in the configuration --enable-libass).

First convert the subtitles to .ass format:

ffmpeg -i sub.srt sub.ass

Then add them using a video filter:

ffmpeg -i in.mp4 -vf ass=sub.ass out.mp4

Extract the frames from a video

To extract all frames from between 1 and 5 seconds, and also between 11 and 15 seconds:

ffmpeg -i in.mp4 -vf select='between(t,1,5)+between(t,11,15)' -vsync 0 out%d.png

To extract one frame per second only:

ffmpeg -i in.mp4 -fps=1 -vsync 0 out%d.png

Rotate a video

Rotate 90 clockwise:

ffmpeg -i in.mov -vf "transpose=1" out.mov

For the transpose parameter you can pass:

0 = 90CounterCLockwise and Vertical Flip (default)
1 = 90Clockwise
2 = 90CounterClockwise
3 = 90Clockwise and Vertical Flip

Use -vf "transpose=2,transpose=2" for 180 degrees.

Download "Transport Stream" video streams

1. Locate the playlist file, e.g. using Chrome > F12 > Network > Filter: m3u8
2. Download and concatenate the video fragments:

ffmpeg -i "path_to_playlist.m3u8" -c copy -bsf:a aac_adtstoasc out.mp4

If you get a "Protocol 'https not on whitelist 'file,crypto'!" error, add the protocol_whitelist option:

ffmpeg -protocol_whitelist "file,http,https,tcp,tls" -i "path_to_playlist.m3u8" -c copy -bsf:a aac_adtstoasc out.mp4

Mute some of the audio

To replace the first 90 seconds of audio with silence:

ffmpeg -i in.mp4 -vcodec copy -af "volume=enable='lte(t,90)':volume=0" out.mp4

151.101.112.133