ffmpeg tricks

Using ffmpeg is quite straightforward following documentation or using oneliners from the web, but I find useful having a quick cheatsheet here for some common tasks. This is not intended to be a guide.

• Animations
  • Extract frames from video
  • Export to GIF
• Video
  • Static image and background sound
  • Rotate 180°
  • List encoders/decoders
  • Scaling
  • Trimming
  • Merging
• Audio
  • Cut audio from one point to other (trim)
  • Extract audio from video

Animations

Extract frames from video

ffmpeg -i input.mp4 frame-%04d.jpg

Export to GIF

Just rename the output so it ends with .gif

Video

Static image with background sound

ffmpeg -loop 1 -i image.jpg -i audio.mp3 -c:a copy -c:v libx264 -shortest out.mp4

Rotate video 180°

ffmpeg -i input.mp4 -vf "hflip,vflip" output.mp4

List encoders/decoders

ffmpeg -encoders
ffmpeg -decoders

Scaling

The example below resizes the output to a width of 320px while keeping the original aspect ratio.

ffmpeg -i input.mp4 -vf "scale=320:-1" output.mp4

It is possible to use iw and ih (initial width, inital height) multiplied/divided by a scalar. More info

Trimming

Using timestamps:

ffmpeg -i input.mp4 -ss 00:12:35 -to 00:12:50 output.mp4

Using values in seconds:

ffmpeg -i input.mp4 -ss 35 -to 50 output.mp4

Use -t (instead of -to) to define length instead of destination time:

ffmpeg -i input.mp4 -ss 35 -t 15 output.mp4

Merging

To merge a series of files one after the other (and copying the audio+video stream):

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

Where list.txt is as follows:

file 'foo.mp4'
file 'bar.mp4'
file 'baz.mp4'

Audio

Trim

Set the ss value to the starting point (in seconds) and t to the desired length (or use -to to set a fixed stop position).

ffmpeg -ss 4 -t 12 -i input.mp3 -acodec copy output.mp3

Extract audio from video

Tip: This may be combined with trimming parameters as well to extract a fragment.

ffmpeg -i input.mp4 -q:a 0 -map a output.mp3