Picture-preserving audio replacement
Replace video audio without re-encoding the picture
Swap a soundtrack, add a voiceover, or mix music with the original track while the encoded video frames are copied unchanged. Only the audio is processed for the output container.
- Copies the original picture stream without re-encoding it.
- Supports replace and mix modes with separate gain controls.
- Handles short audio by padding, looping, or ending at the shortest stream.
Keep the original video frames unchanged
A normal video editor decodes and re-encodes the picture even when the only change is a soundtrack. That takes longer and can introduce generation loss, larger files, or changed color and frame behavior.
This tool maps the original video stream directly into the output with stream copy. The picture bytes are not recompressed. The replacement or mixed audio is encoded to a codec that is valid for the chosen output container.
Replace a track or mix in narration and music
Replace mode removes the original soundtrack and uses the new audio. Mix mode keeps the original track and combines it with the replacement, with separate gain controls for balancing speech, ambient sound, and music.
Mix mode requires the source video to contain audio. If it is silent, use replace mode instead. A limiter protects the mixed output from obvious clipping when two louder tracks are combined.
Control what happens when durations differ
Narration and music rarely have exactly the same duration as the video. You can pad a short track with silence to the video length, loop it, or stop when the shorter stream ends.
Preview the result before downloading, especially when voice timing matters. This workflow replaces or mixes whole tracks; it is not a multi-track timeline editor for sliding audio against individual frames.
How to use this workflow
- 01.Choose the videoAdd the MP4, MOV, WebM, MKV, AVI, M4V, or FLV file whose picture you want to keep.
- 02.Add the new audioChoose a music, narration, or repaired audio file, then decide whether to replace the original track or mix both tracks.
- 03.Set duration and gainsPad or loop short audio, choose the shortest-stream behavior when needed, and balance replacement and original volume before processing.