Dolby AC-4

Dolby AC-4 is an audio compression technology developed by Dolby Laboratories.[1] Dolby AC-4 bitstreams can contain audio channels and/or audio objects.[1] Dolby AC-4 has been adopted by the DVB project and standardized by the ETSI.[2]

History

Its development started in late 2011 to create a high-quality audio format to be used in streaming services, future TV broadcasts, and mainly to replace the traditional Dolby AC-3. AC-4 was standardized by the European Telecommunications Standards Institute (ETSI) under the code "TS 103 190" in April 2014,[1] and in December 2014 Dolby Laboratories approved the sound format for commercial use.

On March 10, 2015, the Advanced Television Systems Committee (ATSC) announced that Dolby AC-4 was one of the three standards proposed for the audio system of ATSC 3.0.[3]

On July 14, 2015, Dolby Laboratories announced that Sony Visual Products and Vizio would support Dolby AC-4.[4]

On April 14, 2016, Dolby Laboratories announced that Samsung

Technical details

Dolby AC-4 can have up to 5.1 core audio channels which all Dolby AC-4 decoders are required to decode.[1] Additional audio channels may be encoded as side signals which Dolby AC-4 decoders can optionally support which would allow for the delivery of 7.1.4 channel audio.[1] Side signals may also contain audio objects.[1] Dolby AC-4 has two different channel based encoding tools with Advanced Joint Channel Coding (A-JCC) used for low bit rates and Advanced Coupling (A-CPL) used for high bit rates.[1] A-JCC doesn't support side signals and is limited to 5.1 channel audio while A-CPL does support side signals.[1] Dolby AC-4 supports up to 7 audio objects with a core decoder and can optionally support additional audio objects with a more advanced decoder.[1] The use of different decoders allows Dolby AC-4 to support lower cost devices while also allowing for more advanced decoders for

Patent licensing

Dolby AC-4 is covered by patents and requires a license from Dolby Laboratories.[8] Dolby AC-4 has a consumer royalty rate of US$0.15 to US$1.20 depending on the type of device and volume of sales.[8] Dolby only charges for one technology per device, which means that Dolby AC-4 effectively costs nothing in devices that include existing Dolby technologies such as Dolby Digital Plus.[8] The professional royalty rate is up to US$50 for an eight channel transcoder.[8]

See also

• Dolby Laboratories
• MPEG-H 3D Audio

External links