VM Mixer is a app that makes you add music to videos easily.
How to use:
1. Open the app.
2. Click the big start button.
3. Select a video from your photo library.
4. Click add music button at the bottom of the editor view.
5. Select a song from your music library.
6. You can change the start or end time of the song, you can also change the volume of the song or video.
7. Click Apply button, then it will merge the song into the video and save it to your photo library automatically.
8. Open your album and you can enjoy it.