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FFMpeg

Command line tool to converts and edits videos.

FFmpeg opens the file, decodes it into memory, then encodes the in-memory packets back and puts them into some container: some output file. The term "codec" is a mix of the words "coder & encoder". Those are the magic parts before and after the "decoded frames".

The decoded frames are uncompressed images in-memory, e.g. the most basic pixel format for video frames is called "rgb24". This just stores red, green, and blue values right after each other in 3x8 bits, or 3x1 byte, which could hold 16m colors.

The importance of this is that other than a few exceptions, you can only manipulate or encode the decoded frames. So when we get to different audio/video filters or transcoding, you'll need the decoded frames for all that. But don't worry, FFmpeg does this automatically for you.

Arguments

-i input

-c encoding -c copy not re-encoded

-ss start position

-to end position

-an audio none

-vf indicates the usage of a video filter

Streams

-map i:[a|v]:n

Extract audio from video

To find out which codec your audio track is using:

ffmpeg -i inputVideo.mp4 -hide_banner

If both the input and outputs are in aac format:

ffmpeg -i inputVideo.mp4 -acodec copy outputAudio.aac

Extract audio to MP3:

ffmpeg -i inputVideo.mp4 outAudio.mp3

Extract audio to WAV:

ffmpeg -i inputVideo.mp4 outAudio.wav

Extract part of video:

ffmpeg -ss 00:03:30 -to 00:03:48 -i input.mp4 -c copy output.mp4

Concat two or more videos

Create a text file and

join.txt

file filename1.mp4
file filename2.mp4

Then run this in bash:

ffmpeg -f concat -safe 0 -i join.txt -c copy output.mp4

Remove audio

ffmpeg -i input.mp4 -an -c:v copy output.mp4

Adding audio to video

ffmpeg -i video.mp4 -i audio.mp3 -map 0:v -map 1:a -c:v copy -c:a copy -shortest output.mp4

With the -map 0:v -map 1:a arguments, the video track from the first input (0:v) and the audio track from the second input (1:a) are mapped to the output. The -c:v copy arguments tell FFmpeg not to re-encode the video. By default, when FFmpeg receives multiple input files, it uses the length of the longest input file as the output duration. We're going to use the shortest duration here, so we'll use -shortest.

Reverse video

ffmpeg -i originalVideo.mp4 -vf reverse reversedVideo.mp4

Convert video

ffmpeg -i "input_file_name.mkv" -map 0 -c copy "output_file_name.mp4"

Change video speed

ffmpeg -i input.mp4 -filter:v "setpts=0.5*PTS" -an output.mp4

0.5 means x2

To slow down your video, you have to use a multiplier greater than 1

Basic Cropping

ffmpeg -i input.mp4 -filter:v "crop=out_w:out_h:x:y" output.mp4

Extract Image

Single image:

ffmpeg -ss 00:00:10 -i input.mp4 -frames:v 1 screenshot.png

Image Overlay

ffmpeg -i video.mp4 -i overlay.png \
	-filter_complex "[0:v][1:v] overlay=0:0" \
	-c:a copy \
	output.mp4

-i video.mp4 is our source video

-i overlay.png is our PNG overlay

-filter_complex "[0:v][1:v] overlay=0:0"

• With [0:v][1:v] we are telling to FFMPEG put the input file with index 0 (the video) under the input file with index 1 (the overlay)

• With overlay=0:0 we are setting the position of our overlay (in this case, top-left corner as our video and overlay have the exact same width/height)

-c:a copy → we want to re-use the audio from the source file

output.mp4 is the name of the output file

Links

https://gist.github.com/travelhawk/4537a79c11fa5e308e6645a0b434cf4f