Touted as the most efficient audio codec in the world, HE-AAC has been adopted as a standard by 3GPP, a collaboration between telecommunications standards bodies to produce global standards and specifications for mobile technologies.
It’s good news for the developing AAC format, and good news for those in the mobile industry – there’s now a good chance there’ll be a common file format for music stores and mobile music. Convergence fans will also be able to transfer music between AAC compatible devices, meaning that it’s less likely they’ll have to buy the same track more than once. Furthermore, the adoption of a standard should encourage more publishers to venture out into mobile music.
aacPlus can store a reasonably high-fidelity single track in just 500kb – obviously hand for the current generation of handsets that are doubly constrained by available bandwidth and memory capacities.
Richard Poston, director of corporate communications at mmO2 said about the news: “As the first operator offering mobile music downloads, we are very happy about the final standardization. We’ve been really impressed by the excellent balance of good audio quality combined with efficient use of bandwidth.”
HE-AAC uses a spectral band replication system from Coding Technologies to reconstruct high frequency sound from hints in the encoded file. By stripping out the high frequencies, only low-frequency sound needs to be encoded and stored, meaning that music can be encoded at roughly half the bit rate of standard AAC.
Perfect if you listen to that “bang bang bang” music, but we’ve yet to test if the high-frequency substitution wheeze can encode other music types, such as those with lots of strings, accurately.