This format was created for online broadcasting. Opus is an audio codec for compression used on the Internet in real-time mode. Employed by programs such as Skype and Mozilla. Mostly used in interactive applications. The advantages of Opus are high audio quality and good compression. It works only on devices powered by Windows. Opus files can be converted to similar extensions.

ac3

AC3: a Dolby Digital audio file

This is an audio file extension that allows for achieving surround sound. It is utilized in files of the DVD format. Its manufacturing company is Dolby Digital. An AC3 file is an audio stream that can be encountered as external soundtracks for films. You can download it separately and synchronize it with the movie file. The audio file contains 6 channels: upper and lower, front and rear, right and left, as well as low-frequency effects.