The MP4 file has become the leading video format for portable media players and smartphones due to its compact data rate. The compression profile manages to stream quality audio and video with relatively low bandwidth. Since MP4 files are popularly used on mobile devices, it may be necessary to increase their volume for on-the-go listening. Apple's QuickTime Pro program can easily and effectively enhance the sound of MP4 files. The premium version of the free QuickTime media player, QuickTime Pro enables users to modify media files by giving them access to encoding functions and advanced A/V controls.
Download and install QuickTime Pro. QuickTime Pro can be purchased and set up through the Apple product page. Users who already use the free QuickTime media player can upgrade to QuickTime Pro by simply purchasing the software license. To upgrade, open the QuickTime media player and go to the "Help" tab on the program menu. Click on "Buy QuickTime Pro" and the Apple product page will automatically launch in an Internet browser window. Complete the checkout process and follow the installation prompts.
Open your MP4 file in QuickTime. If the file does not automatically open in QuickTime, right-click on the file, select "Open With" and choose QuickTime from the list of compatible programs.
Increase the volume on your MP4 file. Go to "Window" on the QuickTime program menu and select "Show Movie Properties" (keyboard command CTRL+J). Click the "Audio Settings" tab and move the "Volume" slider to the right. When you have selected your desired level of volume, click "OK" and exit the "Movie Properties" window.
Save your volumized MP4 file. Go to "File" and select "Save As." Save the file in your preferred location and rename it to indicate the increased volume. Click "OK."
Open your volumized MP4 file. To verify you have successfully created a louder version of your original MP4 file, preview the file with increased volume. If it does not sound louder, start the process over.