A free app for Android, by SigmaCode Tech..
Any video file can have its background music changed with the Audio Video Mixer software. This tool is a form of video editor that lets you add or combine your preferred audio files with video files.
If an audio file is longer than a video file, this software will automatically shorten it to fit the video’s running time.
Feature Examples for Adding Audio to Videos:
Pick a video from your photo gallery.You can mute your video file and add an audio file to it.Define where the background music should start.View the preview of the most recent video.The easiest, most beautiful user interfaceLightweight applicationPost your original music videos and films on social media apps.