Software & Apps File Types How to Open or Convert AC3 Files Share Pin Email Print AC3 File Open in Windows Media Player. Lifewire File Types Design Cryptocurrency MS Office Windows Linux Google Drive Apps File Types Backup & Utilities View More By Tim Fisher General Manager, VP, Lifewire.com Tim Fisher has 30+ years' professional technology support experience. He writes troubleshooting content and is the General Manager of Lifewire. our editorial process Facebook Twitter LinkedIn Tim Fisher Updated June 01, 2019 A file with the AC3 file extension is an Audio Codec 3 file. Much like the MP3 format, the AC3 file format uses lossy compression to reduce the overall size of the file. The AC3 format was created by Dolby Laboratories and is often the sound format used in movie theaters, video games, and DVDs. AC3 audio files are designed to support surround sound. They have separate tracks for each of the six speakers in a surround sound setup. Five of the speakers are dedicated to a normal range and one speaker is dedicated to low-frequency subwoofer output. This corresponds to the configuration of 5:1 surround sound setups. How to Open an AC3 File AC3 files can be opened with Apple's QuickTime, Windows Media Player, MPlayer, VLC, and other multi-format media players, such as CyberLink PowerDVD. If you find that an application on your PC tries to open the AC3 file but it's the wrong application, or if you would rather have another installed program open AC3 files, you can designate a different default program for the AC3 extension files. How to Convert an AC3 File Several free audio converters support converting AC3 files to other audio formats such as MP3, AAC, WAV, M4A, and M4R. Zamzar and FileZigZag, work in your web browser. You just upload the AC3 file to one of the websites, choose an output format, and then save the converted file to your computer.