Browser FFmpeg recipe
Mix Audio with Video Online with FFmpeg
Keep the video and mix its original sound with another audio track.
Command
Run this FFmpeg command
ffmpeg -i video.mp4 -i music.mp3 -filter_complex [0:a][1:a]amix=inputs=2:duration=first:dropout_transition=2[a] -map 0:v -map [a] -c:v copy -c:a aac mixed-audio.mp4When to use it
- background music
- voice plus music
- demo sound beds
How it works
- Upload the video and extra audio file.
- Change music.mp3 to your second audio filename.
- Run FFmpeg and download the mixed output.
Option reference
| Option | What it does |
|---|---|
amix=inputs=2 | Mixes two audio streams together. |
duration=first | Keeps the output aligned to the first input duration. |
-map 0:v -map [a] | Uses the original video and mixed audio output. |
Practical notes
- Lower the music volume first if it overpowers the original audio.
- Mixing audio requires re-encoding the output audio stream.
FAQ
Can I use this for background music?
Yes. Upload the video and music file, then map the music as the second input.
Will the video be re-encoded?
No, this command copies the video stream and re-encodes only the mixed audio.