Does removing audio reduce file size much?

Usually a small amount, since audio is a fraction of a typical video's bitrate — the savings are proportional to how audio-heavy the original encode was.

Can I remove audio from only part of the video?

Not with a single -an flag, which applies to the whole file — for a partial mute, use the volume filter with an enable expression instead, e.g. volume=0:enable='between(t,5,10)' .

Will this work on formats other than MP4?

Yes, the same flags apply to any container FFmpeg supports.

How to Remove Audio From a Video With FFmpeg

Stripping the audio track entirely, without re-encoding the video — useful before adding a new voiceover or music track.

The command

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

What each flag does

-c copy	Copies the video stream without re-encoding — instant, lossless.
-an	Excludes audio from the output entirely.

Where this goes wrong

People sometimes reach for a slower re-encoding command out of habit when removing audio doesn't require touching the video at all — -c copy -an runs in roughly the time it takes to read and write the file, regardless of length.

If you want silence instead of no audio track

ffmpeg -i input.mp4 -f lavfi -i anullsrc -c:v copy -c:a aac -shortest output.mp4

Some platforms and editing tools expect every video to have an audio track, even a silent one. This generates a silent track with anullsrc and trims it to match the video's length with -shortest.

After the command

Once you're rebuilding the audio layer from scratch — a voiceover, captions, sound effects — that's the exact job NULLFRAME's templates automate on top of your video.

See the templates

How to Remove Audio From a Video With FFmpeg

The command

What each flag does

Where this goes wrong

If you want silence instead of no audio track

Common questions