How to add music to a video and keep the original voice
To put background music under a voice that is already in your video, choose mixing rather than replacing the original sound. FlareClip lets you upload a video and an audio file, adjust their levels and export an MP4. Start with quiet music and listen to the finished result before sharing.
1. Choose your video and music
Select a video you own or have permission to use, then add an audio file you are allowed to include in the finished video. Supported inputs include compatible MP4, MOV and WebM videos, plus MP3, WAV or M4A audio up to 100 MB. This workflow uses an audio file you supply; choosing a song does not grant permission to publish it.
2. Select mixing to keep the voice
The tool starts in Replace original sound mode. Change it to Mix with original sound if you want to keep the video's existing voice. Adjust Original volume and New audio volume, starting with music below the speech. Mixing affects the selected original soundtrack as a whole: it does not separate its voice from music already in that track or automatically lower the new music whenever someone speaks.
3. Decide how the music ends
The output follows the video's duration. Music that is longer than the video ends with the video. If it is shorter, enable Repeat new audio to keep it playing; otherwise the added music stops and the video continues. In mix mode, the selected original sound can continue after the music ends. Use fade-in or fade-out if helpful, keeping their combined length within the active music duration.
4. Inspect the inputs and confirm the tracks
Preview your choices and confirm your right to use both files. Request input inspection and follow any sign-in or account prompts. Once inspection finishes, check the chosen audio tracks. If a source has several tracks, select the one you need and confirm the selection: other tracks will not be retained in this mix. Check the expected output, then confirm export.
5. Listen to the finished MP4
Play a passage with speech in the completed result, as well as the beginning, music ending and video ending. Check whether the voice remains understandable and the repeat or fades sound right. Mixing reserves level headroom, so compare by listening rather than expecting the source's original loudness. Download the reviewed MP4 and open the saved file before sharing.