Replace the Audio in a Video, Free and Private
Swap the soundtrack of an MP4, MOV, MKV or WebM file without re-encoding the picture. Set the new audio to the millisecond. No upload, no watermark, no account.
Last updated: November 2, 2026
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Replace is for the clip where the picture is right and the sound is not: a noisy room, a phone recording, a take with a stumble in the middle. Drop the video, drop the new audio, and set where it begins.
The original audio track is discarded. The video stream is copied, not re-encoded, so a 4K clip stays 4K and a 60 fps clip stays 60 fps. The new audio is encoded to AAC at 128, 192 or 256 kbps.
A short track can play once or loop until the video ends. Fade in and fade out keep the edges clean, and the level control lets the new audio sit below or above the original.
Need the other two modes? They live in the main Add Audio to Video tool.
Replace Audio Questions
Formats, quality and what happens to the file.No, not when the video codec can be stored in MP4. The video packets are copied, so resolution, bitrate and colour do not change. If the codec cannot be copied, the page says so and re-encodes to H.264.