[2] 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.
[citation needed] 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.
[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] AC-4 uses an improved modified discrete cosine transform (MDCT) audio coding algorithm.
[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.