notebook/IT/Ffmpeg.md

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

Remux an MKV file into MP4

ffmpeg -i in.mkv -c:v copy -c:a copy out.mp4

High-quality encoding

Use the crf (Constant Rate Factor) parameter to control the output quality. The lower crf, the higher the quality (range: 0-51). The default value is 23, and visually lossless compression corresponds to -crf 18. Use the preset parameter to control the speed of the compression process. Additional info: https://trac.ffmpeg.org/wiki/Encode/H.264

ffmpeg -i in.mp4 -preset slower -crf 18 out.mp4

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. Loate 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

To replace all audio between 1'20" and 1'30" with silence:

ffmpeg -i in.mp4 -vcodec copy -af "volume=enable='between(t,80,90)':volume=0" out.mp4

Deinterlace

Deinterlacing using "yet another deinterlacing filter".

ffmpeg -i in.mp4 -vf yadif out.mp4

Create a video slideshow from images

Parameters: -r marks the image framerate (inverse time of each image); -vf fps=25 marks the true framerate of the output.

ffmpeg -r 1/5 -i img%03d.png -c:v libx264 -vf fps=25 -pix_fmt yuv420p out.mp4

Extract images from a video

• Extract all frames: ffmpeg -i input.mp4 thumb%04d.jpg -hide_banner
• Extract a frame each second: ffmpeg -i input.mp4 -vf fps=1 thumb%04d.jpg -hide_banner
• Extract only one frame: ffmpeg -i input.mp4 -ss 00:00:10.000 -vframes 1 thumb.jpg

Metadata: Change the title

ffmpeg -i in.mp4 -map_metadata -1 -metadata title="My Title" -c:v copy -c:a
copy out.mp4