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View Full Version : AC-4 : the new Audio Codec Standard


Kurtnoise
15th May 2014, 07:51
Since few days, ETSI has released (http://www.etsi.org/news-events/news/783-2014-04-etsi-releases-ac-4-the-new-generation-audio-codec-standard) the specifications of the successor of the AC-3 format. The new brand is just called AC-4...:p

Specs are available here (http://www.etsi.org/deliver/etsi_ts/103100_103199/103190/01.01.01_60/ts_103190v010101p.pdf).

And looks like we can put the stream in ISO files, like AC-3...

pandy
19th May 2014, 13:13
Brand "new" codec (MDCT based)... Yupi...

Thx Kurtnoise for info!

Who is the patent owner and to whom we will pay royalties?

Kurtnoise
19th May 2014, 14:07
Dunno...

mandarinka
19th May 2014, 16:25
Brand "new" codec (MDCT based)... Yupi...

Thx Kurtnoise for info!

Who is the patent owner and to whom we will pay royalties?

From page 16 of the pdf:

IPRs essential or potentially essential to the present document may have been declared to ETSI. The information
pertaining to these essential IPRs, if any, is publicly available for ETSI members and non-members, and can be found in ETSI SR 000 314: "Intellectual Property Rights (IPRs); Essential, or potentially Essential, IPRs notified to ETSI in respect of ETSI standards", which is available from the ETSI Secretariat. Latest updates are available on the ETSI Web server (http://ipr.etsi.org).
Pursuant to the ETSI IPR Policy, no investigation, including IPR searches, has been carried out by ETSI. No guarantee can be given as to the existence of other IPRs not referenced in ETSI SR 000 314 (or the updates on the ETSI Web server) which are, or may be, or may become, essential to the present document.

BTW, it doesn't look like a plain "MDCT" scheme, it is probably going to be more complex, just looking at the contents, it seem to have a split-architecture like Opus (Silk + Celt), there is "audio spectral frontend" and "speech spectral frontend". Also there is something about high frequencies construction (" Advanced spectral extension tool" - something like SBR?). Also I see something about channel coupling, but that's really just a glance.

It might turn out to be interesting...