FFmpeg Tips and Tricks

October 15th, 2021

Here’s a small selection of cool things you can do on Linux with FFmpeg.

Convert Between Video Formats

The most basic, simple, and useful thing to do with FFmpeg:

$ ffmpeg -i input.m4v output.mp4

For example, to convert MOV to MP4

$ ffmpeg -i movie.mov -vcodec copy -acodec copy out.mp4

You can also use Handbrake to drive these conversions through a GUI.

Create Animated GIFs

There are two ways to do this: first by generating the frames in a subfolder, and then concatenating everything with convert:

$ ffmpeg -i video.mp4 -r 5 'frames/frame-%03d.jpg'
$ convert -delay 20 -loop 0 frames/*.jpg myimage.gif

Where -r in the first command stands for the frames per second caught in the GIF.

But can do this without convert in one shot:

$ ffmpeg -i portal.mp4 -r 5 portal.gif

Trim Video

Generate a subclip of a video, removing frames before and after some reference points:

$ ffmpeg -i input.mp4 -ss 00:01:15 -t 00:00:30 -async 1 output.mp4

The -ss parameter is the starting point.
The -t provides the length of the clip.

Make Video Smaller

Smaller in bytes:

$ ffmpeg -i input.mp4 -vcodec libx265 -crf 20 output.mp4

Smaller in width and height:

$ ffmpeg -i input.avi -s 720x480 -c:a copy output.mkv

Make a Video compatible with QuickTime

This should make a video that is Mac-friendly:

$ ffmpeg -i input.webm -f mp4 -vcodec libx264 \
         -pix_fmt yuv420p output.mp4

Make Videos Compatible with Windows Media

This creates an AVI file that is compabible… with Windows 95!

$ ffmpeg -i input.mp4 -vcodec msvideo1 -acodec adpcm_ms \
         -vf scale=320:240 -f avi output.avi

The scale information is required, and width and height must be multiples of 4 for the msvideo1 encoder.
The avi parameter selects the container format.

Split Video

As the title implies:

$ ffmpeg -i largefile.mp4 -t 00:50:00 -c copy smallfile1.mp4 \
       -ss 00:50:00 -c copy smallfile2.mp4

Concatenate Video Files

The inverse operation as above; create a playlist.txt file with this structure:

# Playlist
file 'part-1.mkv'
file 'part-2.mkv'
file 'part-3.mkv'

And then concatenate all movies together:

$ ffmpeg -f concat -safe 0 -i playlist.txt -c copy output.mkv

To make sure the audio works in QuickTime / iOS when using a playlist:

$ ffmpeg -f concat -safe 0 -i playlist.txt -c:v copy -c:a aac output.mp4

Better Concatenation

The script below performs a better concatenation using intermediate files.

#!/usr/bin/env bash

# This script merges all video files into one.
# It requires ffmpeg:
# Linux: sudo apt install ffmpeg
# Mac: brew install ffmpeg

ffmpeg -i part0.mp4 -c copy -bsf:v h264_mp4toannexb -f mpegts int0.ts
ffmpeg -i part1.mp4 -c copy -bsf:v h264_mp4toannexb -f mpegts int1.ts
ffmpeg -i part2.mp4 -c copy -bsf:v h264_mp4toannexb -f mpegts int2.ts
ffmpeg -i part3.mp4 -c copy -bsf:v h264_mp4toannexb -f mpegts int3.ts
ffmpeg -i part5.mp4 -c copy -bsf:v h264_mp4toannexb -f mpegts int5.ts
ffmpeg -i part6.mp4 -c copy -bsf:v h264_mp4toannexb -f mpegts int6.ts
ffmpeg -i "concat:int0.ts|int1.ts|int2.ts|int3.ts|int5.ts|int6.ts" \
       -c copy -bsf:a aac_adtstoasc output.mp4
rm *.ts

Concatenating video files requires the audio to be in the same format, for example in AAC:

$ ffmpeg -i input.mp4 -c:v copy -c:a aac output.mp4

Record your Webcam

This command records your webcam and generates a video file:

$ ffmpeg -f oss -i /dev/dsp -f video4linux2 -s 320x240 \
         -i /dev/video0 out.mpg

The /dev/video0 part should match your own webcam; to find it, for example if your laptop has an integrated webcam but you also have a USB Logitech camera connected:

$ sudo apt install v4l-utils
$ v4l2-ctl --list-devices

    Logitech Webcam C930e (usb-0000:00:14.0-3.1):
        /dev/video2
        /dev/video3

    Integrated Camera: Integrated C (usb-0000:00:14.0-8):
        /dev/video0
        /dev/video1

Update, 2022-09-30: You can download and merge all the files referenced in a M3U8 video stream into a single file with this command: ffmpeg -i "http://example.com/stream.m3u8" -c copy -bsf:a aac_adtstoasc "output.mp4"(source), or you can just use youtube-dl for that.

Update, 2023-02-24: Extract the audio track from a video using ffmpeg -i input.mp4 -vn -acodec copy output.aac.

Update, 2023-05-19: For lossless and super fast conversion between AVI and MP4, just use ffmpeg -i input.avi -c:v copy -c:a copy -y output.mp4