What is AC-3?
AC-3 is an audio compression codec created by Dolby Labs and is one of two audio formats that are universally compatible with all DVD players in all regions. The other is PCM, which is the same uncompressed audio signal that is on music CDs. Although “Dolby Digital” is AC-3 by another name, an AC-3 signal does not imply that the audio is in surround sound. An AC-3 signal can be mono, stereo, 4-channel surround, 5-channel surround, or 5.1-channel surround. By getting rid of sound information that humans have difficulty discerning, AC-3 is able to highly compress audio while retaining most of the perceived sonic quality. A stereo AC-3 stream typically runs at 192KB/second, compared to 1,536KB/second for uncompressed 16-bit/48KHz PCM audio. Even 5.1 surround sound in AC-3 format is typically encoded at just 224KB/second (surround sound is not supported in PCM format on DVD). Other sound formats found on DVD video include MPEG2 Layer 1 for legacy compatibility, and DTS for high-quality sur
