Add Audio to Video
Put music or a voice-over on a video.
Drop your video here
MP4, MOV, WebM, MKV, AVI…
Drop the audio file (MP3, WAV, M4A…)
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Uses ffmpeg.wasm: about 30 MB is downloaded the first time, then cached. Processing speed depends on your device — a 1-minute 1080p clip takes roughly 1–3 minutes.
● Your video is processed locally in your browser and never uploaded. Large files need a recent computer with enough memory.
How it works
The picture is copied without re-encoding (no quality loss); only the sound is processed and encoded to AAC. In mix mode both tracks are combined with ffmpeg's amix filter at the volumes you choose. The result always stops at the end of the video; loop short music to fill it.