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.

[IgorC]

Maybe it's this particular encoder.

Because I have tried USAC files from official test and it was quite good. http://www.hydrogenaudio.org/forums/index....st&p=797609

[C.R.Helmrich]

Because I have tried USAC files from official test and it was quite good. Is there any possibility that there will be a commercial encoder besides of reference implementation?

Those files from the USAC verification test were created with an unpublished reference quality encoder, not the reference software. I'm confident that an encoder similar to this reference quality encoder will be available for purchase in the near future.

Will it stay mono or will that change? I could see the point in removing some parts of the good encoder so you can license a few copies of the true good encoder, but the stereo coding seems to be an important part of USAC, so leaving that out seems to undermine the point?

I know and agree, but don't know if/when it will be able to do stereo.

Chris