The AC-3 file extension, or Audio Coding 3, is used for audio files and was developed in 1987 by Dolby Laboratories. Its use was focused on Blu-ray, DVDs and HDTV programming, and it became very popular with home theater fans.
Today, the vast majority of HDTV audio-video programs use the AC-3 standard format, combining it with HD signal television broadcasts. AC-3 operates at sound frequencies from 20 to 20,000Hz, covering all the needs of the human ear in this respect.
On DVD, its bit rate can reach 640kbps, and the average rate is 48kHz. AC-3 represents the most widely used audio extension in DTV and DVDs, and can be easily converted to other well-known file types such as MPEG or AVI.
As for how it works, it is called perceptual compression. It removes all the parts of the sound that the human ear cannot pick up, compressing the information and allowing further modifications.
