About me: My name is Solène Rapenne, pronouns she/her. I like learning and sharing knowledge. Hobbies: '(NixOS BSD OpenBSD Lisp cmdline gaming security QubesOS internet-stuff). I love percent and lambda characters. OpenBSD developer solene@.

Contact me: solene+www at dataswamp dot org or @solene@bsd.network (mastodon). If for some reason you want to support my work, this is my paypal address: donate@perso.pw.

Consider sponsoring me on Patreon to help me writing this blog and contributing to Free Software as my daily job.

Separate or merge audio and video using ffmpeg

Written by Solène, on 20 December 2019.
Tags: #ffmpeg

Comments on Fediverse/Mastodon

Extract audio and video (separation)

If for some reasons you want to separate the audio and the video from a file you can use those commands:

ffmpeg -i input_file.flv -vn -acodec copy audio.aac

ffmpeg -i input_file.flv -an -vcodec copy video.mp4

Short explanation:

  • -vn means -video null and so you discard video
  • -an means -audio null and so you discard audio
  • codec copy means the output is using original format from the file. If the audio is mp3 then the output file will be a mp3 whatever the extension you choose.

Instead of using codec copy you can choose a different codec for the extracted file, but copy is a good choice, it performs really fast because you don’t need to re-encode it and is loss-less.

I use this to rework the audio with audacity.

Merge audio and video into a single file (merge)

After you reworked tracks (audio and/or video) of your file, you can combine them into a single file.

ffmpeg -i input_audio.aac -i input_video.mp4 -acodec copy -vcodec copy -f flv merged_video.flv