audio/ac3

The 5.1 surround sound of the DVD era: AC-3, marketed as Dolby Digital, is the multichannel codec ATSC television, DVDs, and a generation of home theater receivers standardized on. The media type arrived through the streaming door — RFC 4184 (2005), written at Dolby, registers audio/ac3 for RTP transport with a required rate parameter locked to 32000, 44100, or 48000 Hz. As a file, AC-3 is usually a raw elementary bitstream of frames each opening with the 0b 77 sync word — a per-frame marker rather than a proper file signature, since streams can begin at any frame. Its successor E-AC-3 (Dolby Digital Plus) is a separate type, audio/eac3.

Defined by RFC 4184 · IANA registration. Registry facts from the IANA media-types registry via mime-db.