Skip to main content

Topic: xHE-AAC. Is it ready yet? Any encoders out there? (Read 11559 times) previous topic - next topic

0 Members and 1 Guest are viewing this topic.
  • IgorC
  • [*][*][*][*][*]
Re: xHE-AAC. Is it ready yet? Any encoders out there?
Reply #25
From the same paper https://dl.dropboxusercontent.com/u/61700377/misc/20130920_Streaming_Codec_Study_Report.pdf

Quote
Interestingly, results were quite flat starting at 32 kbps, suggesting that listeners did not hear marked
improvements at higher bit rates
:o
This is so wrong I don't even know which argument to start with.
Let's just put it in a technical terms.

If your codec and /or test present the same not so good quality (MUSHRA 60 = MOS 3) both at 24-32 kbps and higher bitrate 64 kbps then there is something really wrong with your codec and/or test. 

Also according to their test  their xHE-AAC 64 kbps = MP3 96 kbps. Even MP3pro (MP3+SBR) 64 kbps is on par with legacy MP3 96 kbps. So  this particular tested implementation of xHE-AAC doesn't bring nothing new to 14 years old SBR (?). 




Another interesting statement about bitrates and 4G.
Quote
Based on our research, we recommend keeping the bit rate of streams
as low as possible, consistent with high audio quality.  For the HE‐AAC codec, we believe this balance is achieved
at a constant stream rate of 48 kbps

Something obvious but still.  Audio quality isn't  high  at 48 kbps with any codec. OK quality, maybe.

 I don't beleive that such low bitrate 48 kbps can prevent dropout.
1. It's impossible to "pre-buffer" a real-time radio.
2. The rate of 4G is far superior than any logical audio bitrates. I have an unlimited 4G 30 Mbits connection on my phone. A speed  can drop down to ~300-700 kbps in worst congestion case (and I still get Spotify working at 96/160/320 kbps)
Still far superior to 48-100 kbps.  But if there is some area with no 4G You lose a connection per completely then  even xHE-AAC 16 kbps won't help here.

So all this point of very low bitrate on 4G is very moot.

P.S. They push low bitrates and xHE-AAC for an obvious reason.
Why would someone pay more if LC-AAC (which is almost 20 years old) is doing already great at  80-96 kbps without all that extra pay for a newer low-bitrate codec with a load of patents for semi-parametric or parametric coding tools like SBR, PS, SBS, MPS, advanced LPC, IGF, ELT etc.
  • Last Edit: 09 October, 2016, 02:32:38 PM by IgorC

  • polemon
  • [*][*][*][*]
Re: xHE-AAC. Is it ready yet? Any encoders out there?
Reply #26
IgorC: A result like that is a little shaky, and I think their graphs are a little weird, too.

I think as for low bitrates in the mobile market it doesn't make much sense these days, as providers are pushing for higher bandwidths constantly.
A point where it makes sense to me though, is when it comes to streaming costs. Most providers (mine included) charge for traffic volume. So, when you have less traffic you pay less, so that makes sense. Especially, when you're using that streaming service in your car, etc. where sound quality isn't perfect anyway.

But I'm only really interested in how it performs against Opus. What they claim is one thing, as long as I can't test it myself, it's not really that interesting to me. I don't see myself using DRM over AM, as I don't really have a need for that. But I guess it'd make sense if you're in a remote area, or on a boat or something, and all you can get is AM radio.

I'm a big fan of Codec2, which to me covers the "lower end" of the bandwidth spectrum. I'm a little surprised by the fact the radio operators don't settle on Opus, as it is free, it is a low-latency codec, and provides adequate quality on low bandwidths. I'm not a marketing person, so I guess there's something I simply don't see.

  • IgorC
  • [*][*][*][*][*]
Re: xHE-AAC. Is it ready yet? Any encoders out there?
Reply #27
polemon,
Quote
Most providers (mine included) charge for traffic volume. So, when you have less traffic you pay less, so that makes sense.
That's true.

Quote
But I'm only really interested in how it performs against Opus.
That depends on particular implmentation(encoder) of xHE-AAC.
While there is only one Opus reference implementation there can be multiple xHE-AAC encoders with different audio quality.

You can find some samples of USAC (xHE-AAC) here https://hydrogenaud.io/index.php/topic,106938.msg875351.html#msg875351
That is a reference high quality USAC encoder which isn't available.

I have compared it with Opus some years ago and here are my conslusions:
32 kbps, stereo. USAC is better than Opus.  It's not a surprise as Opus is a low-delay codec and frequency leakeage is big at very low bitrate. While USAC benefits from 100+ ms delay.

48 kbps, stereo. That's where it starts changing. Opus 1.1 was somwehat inferior to HE-AAC and USAC. But the latest alpha 1.2 should be already on par with USAC and somewhat better than HE-AAC.

64 kbps and higher bitrates, stereo. That's where both Opus and USAC already push the limits what can be done with lossy audio compression. Both are good and better than HE-AAC and LC-AAC. It will take at least 5 years or so to make something better than that.

But that's with USAC reference highest quality encoder which isn't available publicly.
That particular xHE-AAC encoder from paper isn't very high qualtiy implementation of standard.
If You want to know an average MUSHRA scores for Opus  the I can provide them knowing the previous results of Hydrogenaudio tests and from my personal experience with it.
MUSHRA:
Opus 48 kbps ~65-70.
Opus 64 kbps ~80-85
Opus 96 kbps ~90-95

The main rule is MOS (hydrogenaudio tests) = MUSHRA/20

Also there is some information about Opus vs EVS (enhanced for low delay xHE-AAC) at 48 kbps, mono
https://hydrogenaud.io/index.php/topic,106938.msg875399.html#msg875399
But Opus 1.2 (which is in development now) shoud do better
  • Last Edit: 10 October, 2016, 02:18:41 PM by IgorC

  • rogeriol
  • [*]
Re: xHE-AAC. Is it ready yet? Any encoders out there?
Reply #28
it's a shame that no encoders are available for general use. it seems this codec is very restricted, only in dedicated hw for now.

  • polemon
  • [*][*][*][*]
Re: xHE-AAC. Is it ready yet? Any encoders out there?
Reply #29
As I was looking into AMR codecs, I've stumbled over this page: http://www.voiceage.com/Patent-Portfolio.html
I don't know how authoritative it is, but I was told, that U-Boat patents are mostly a thing of the past. Given what is described there, patents for xHE-AAC will expire in 2031 - or to be more precise: the last one of those will expire in 2031.

According to this: https://www.iis.fraunhofer.de/en/ff/amm/impl.html there are SDKs available, that run on a plethora of systems, including PC (including Linux). How to get those SDKs, I have no idea.

VoiceAge "sells" xHE-AAC: http://www.voiceage.com/xHE-AAC.html however I'm not sure how they sell it. They claim to be a "codec provider", I wonder if that means, they do anything beyond licensing, really. As far as I understand it, the SDK or whatever software has to come from FhG IIS anyway.

I occasionally check out the usual places on the internet for a pirated copy of the SDK, but so far I couldn't find any. I guess since there aren't that many users, the probability of the SDK leaking outside of its designed realm is rather minimal. And tbh, I think this is the only way we'd get a chance at having a go at xHE-AAC for anytime soon.

  • IgorC
  • [*][*][*][*][*]
Re: xHE-AAC. Is it ready yet? Any encoders out there?
Reply #30
Internet isn't a viable option for patented formats anymore.
Google tries to get rid of AAC in Youtube (still supported in MS and Apple browsers )and pushes Opus. Spotify uses Vorbis and they can't afford a patented format. WhatsApp uses Opus. Netflix uses patent free formats for mobile clients as well. 

MPEG Surround is a standard since 2007 (10 years ago! ) and its presence is null in internet community.
The same goes for xHE-AAC. Something is telling me (and I don't know what is it  O:) ) the same will go for a latest standard 3DA which improves xHE-AAC quality furthermore.

If there is possibility for a new codec in future that will be available for internet community that will be Ghost (or whatever it will be called).  https://people.xiph.org/~xiphmont/demo/ghost/demo.html

Ghost can improve quality  comparing to Opus more than considerably as it can use higher latencies (100-200ms) and some additional complexity. Today ARM chips  can decode at least 2x-4x complexity of Opus without dropping smartphone's battery life.

PS. BTW  xHE-AAC's sweet spot is 24-32 kbps stereo. It's slightly better than HE-AAC at  >=48kbp bitrates. 
Chances that xHE-AAC will be any better than Opus at >=48 kbps are zero.

PS2. There is also a new format AC4 from Dolby. Dolby has acquired Coding Technologies (creators of SBR and Parametric Stereo). AC4 is similar to xHE-AAC (if not better)
  • Last Edit: 16 August, 2017, 01:04:20 PM by IgorC

  • polemon
  • [*][*][*][*]
Re: xHE-AAC. Is it ready yet? Any encoders out there?
Reply #31
If there is possibility for a new codec in future that will be available for internet community that will be Ghost (or whatever it will be called). https://people.xiph.org/~xiphmont/demo/ghost/demo.html

Ghost can improve quality comparing to Opus more than considerably as it can use higher latencies (100-200ms) and some additional complexity. Today ARM chips  can decode at least 2x-4x complexity of Opus without dropping smartphone's battery life.
OK, so when it uses higher latencies, it's meant just for unicast streaming, etc.? Opus was designed to be a low-latency codec for VoIP, etc. that just happened to be good all round.

So Ghost will not replace Opus, merely it will be the "true" replacement for Vorbis, I take it?

  • IgorC
  • [*][*][*][*][*]
Re: xHE-AAC. Is it ready yet? Any encoders out there?
Reply #32
You're right.

  • eahm
  • [*][*][*][*][*]
Re: xHE-AAC. Is it ready yet? Any encoders out there?
Reply #33
Amazing stuff and ideas but... Ghost really? Should we create an association to pick names for open source projects? :)

  • IgorC
  • [*][*][*][*][*]
Re: xHE-AAC. Is it ready yet? Any encoders out there?
Reply #34
 Vorbis, Opus and Ghost aren't names that I would prefer either.   :)

In my opinion some generic naming like Open Audio Codec 1 (OAC1) as for Vorbis , low delay OAC2 (LD-OAC2) as for Opus are easy to understand.
Even better,  Xiph Audio I (XA1, XA2...).

The future royalty-free video codec is "AV1" (AOMedia Video 1).  More clear impossible.
  • Last Edit: 16 August, 2017, 02:35:52 PM by IgorC

  • polemon
  • [*][*][*][*]
Re: xHE-AAC. Is it ready yet? Any encoders out there?
Reply #35
Vorbis, Opus and Ghost aren't names that I would prefer either.

Well, the names like that are usually chosen for the same reason Linux distributions have names like "Ubntu" or "Fedora". The idea is to have a nice martketable name, which also speaks to a community, etc.

However this might swing ther other way: the MPEG numbering, layering, parting and whatever becomes a complete mess, with overlapping naming schemes and naming collisions.

the ITU has a numbering scheme which works half-good, I'd say, but it's still somewhat confusing.

The On2 VPn numbering scheme for video codecs was fine, I think, though. Numbering schemes usually tend to overcomplicate things, so I'm kinda not in favor of that. I'd name it after the person or group mainly involved in its invention or development, similar to how naming works with things like RSA, LZW, Keccak, etc.

  • Klimis
  • [*]
Re: xHE-AAC. Is it ready yet? Any encoders out there?
Reply #36
If there is possibility for a new codec in future that will be available for internet community that will be Ghost (or whatever it will be called).  https://people.xiph.org/~xiphmont/demo/ghost/demo.html

Ghost can improve quality  comparing to Opus more than considerably as it can use higher latencies (100-200ms) and some additional complexity. Today ARM chips  can decode at least 2x-4x complexity of Opus without dropping smartphone's battery life.
I wait for that day so eagerly. They are dropping some serious promises/targets on the table. This format could be a real game changer if and when it will be a thing. I hope we won't have to wait so long for it.

  • polemon
  • [*][*][*][*]
Re: xHE-AAC. Is it ready yet? Any encoders out there?
Reply #37
It seems Ghost is back at being in limbo: https://wiki.xiph.org/Ghost

IgorC: did you do this on their talk page: https://wiki.xiph.org/Talk:Ghost ¦D

Monty's page says "Copyright 2011" and I doubt there has been any changes to it since.

xiph.org has a thing for silly sounding names, their project name on the forefront of that, etc. But also "Vorbis", "Daala", "Ogg".

  • IgorC
  • [*][*][*][*][*]
Re: xHE-AAC. Is it ready yet? Any encoders out there?
Reply #38
IgorC: did you do this on their talk page: https://wiki.xiph.org/Talk:Ghost ¦D
No, I didn't.

It seems Ghost is back at being in limbo: https://wiki.xiph.org/Ghost
Pretty much it is at this moment.