New Standard: USAC, sussesor of (HE)-AAC Options

[IgorC]

It's a new standard (Unified Speech and Audio Coding – USAC, aka MPEG-D part 3).
It has reached a status of Final Draft International Standard.

Basic information http://en.wikipedia.org/wiki/Unified_Speech_and_Audio_Coding
There are some papers about new compression schemes in internet.

There was a verification test where USAC was compared to HE-AAC v1/v2 on range of bitrates 8-96 kbps. http://mpeg.chiariglione.org/meetings/tori...orino_press.htm
The report should be available in September – October.

Some anonymous source has indicated that USAC was clearly superior to HE-AAC and it did very good on speech though something like "USAC at 48 kpbs = HE-AAC at 64 kbps" shouldn't be expected. It's more like 20-25% of bitrate gain at 20-32 kbps and 10-12% at 64 kbps. That's still pretty good.

There is no information if USAC will be used at higher bitrates as ( LC-AAC's area). The core coder of USAC includes a new enhanced SBR (eSBR).
Both SBR and new eSBR have no advantage over LC-AAC at bitrates higher than 80 kbps. It’s unclear if eSBR can be disabled at higher bitrates.


It will be interesting to hear opinions and if somebody knows something more about it.

[C.R.Helmrich]

Thanks for posting that link, Igor! I've also been waiting for the publication of the report, namely Figures 3 and 6.

To answer your question: (e)SBR - just like any other coding tool in USAC, I think - can be turned off. In fact, we did so when testing the new stereo tool intended for "bitrates where SBR is typically not used" (the report of that experiment is available here).

By the way, in case anyone is wondering: I think (hope) that the final version of the standard will also specify native support for gapless playback and ReplayGain/R128.

And one more note: the name USAC will probably change.

Chris

[IgorC]

Thanks for posting that link, Igor! I've also been waiting for the publication of the report, namely Figures 3 and 6.

To answer your question: (e)SBR - just like any other coding tool in USAC, I think - can be turned off. In fact, we did so when testing the new stereo tool intended for "bitrates where SBR is typically not used" (the report of that experiment is available here).

And one more note: the name USAC will probably change.

Chris

Thank You too for paper, Chris. Though I've already read all related papers from that link and other as well.