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Topic: xHE-AAC. Is it ready yet? Any encoders out there? (Read 16841 times) previous topic - next topic
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Re: xHE-AAC. Is it ready yet? Any encoders out there?

Reply #50
About codec2 hold your breath because we have now parametric-WaveNet, basically codec2 at 2.4Kbps decoded using a wavenet model.
WOW that's some serious audio black magic and witchcraft!
Makes me wonder if the idea of deep machine learning could be applied on a general purpose codec (instead of just speech codec) to achieve a similar efficiency ratio.
Deep machine learning is really revolutionarizing computing as we knew it up until now.

Re: xHE-AAC. Is it ready yet? Any encoders out there?

Reply #51
I think xHE-AAC is ready to rock! I run 4 Internet Radio stations and all 4 have xHE-AAC streams (as well as 64kbps HE-AACv1, 320 kbps AAC stereo and 320kbps AAC 5.1 Surround streams). The encoders I use are software called StreamS Hi-Fi Encoders running on a Windows 10 Pro PC. The same PC is also running Orban Optimod PCn audio processing. Output from the Orban travels via Virtual Audio Cables to the StreamS Encoders.

I have both legacy Icecast and HLS streams running. At the moment StreamS Hi-Fi Radio for iOS and tvOS is the only player I'm aware of that can play the xHE-AAC streams. Last year Via Licensing changed the terms for xHE-AAC making it freely available to all existing AAC licensees which should encourage development of a lot more xHE-AAC players on various platforms.

My main xHE-AAC streams are 40kbps (average bit-rate) 48kHz sampling rate HLS format and are listed in the StreamS Hi-Fi Radio app directory. I also have 32kbps (constant bit-rate) 48kHz sampling rate Icecast format xHE-AAC streams for testing purposes. I think the 32kbps streams sound very good but to my ears 40kbps is the sweet spot for achieving true high-fidelity sound. Others' opinions may vary.

I archived a bit over half an hour of one of my stations off the 40kbps xHE-AAC HLS feeding my iPhone running StreamS Hi-Fi Radio to my Mac using AirPlay and Airfoil Satellite (on May 7th 2018 starting at 5:48 pm Pacific). I then output Airfoil Satellite to a virtual audio device with an app called Loopback and then recorded that with Audio Hijack in Apple Lossless Codec format (48kHz sampling rate). AirPlay also uses Apple Lossless Codec so the resulting recording should provide an accurate listening experience comparable to hearing the live broadcast with the iPhone app.

Anyone interested in this listening experience can download the file at this URL: LG73 xHE-AAC Sample in Apple Lossless Codec (zip format). The download will be available for a limited time. Anyone who has StreamS Hi-Fi Radio for iOS and tvOS can find my four xHE-AAC streams in the app directory and experience the xHE-AAC streams live. The stations are LG73.CA, MaxRadio.CA, NewWestRock.CA and UptownRadio.CA. Formats are Pop, Eclectic, Classic Soul and Classic Rock respectively. At the moment all four stations are running identical Optimod settings.

I may be considered a blasphemer around these parts for saying the following (seems like there are a lot of open source fans here), but I believe xHE-AAC is the best codec for any stream running between 8kbps and 40kbps bitrate. I've done some extensive testing with Opus (v1.2.1 encoder in the app LadioCast) and found it was tolerable at 48kbps but even at that higher bit-rate to my ears was inferior to 40kbps xHE-AAC. At 40kbps and below I found Opus v1.2.1 was unacceptable. I have no experience yet with "Codec" or with Opus v1.3 beta.


Re: xHE-AAC. Is it ready yet? Any encoders out there?

Reply #52
Well, we kinda identified the application is very niche. So that kinda proves the point.

However, I'd like to know where you got your encoders from, and whether these are the xHE-AAC hardware encoders or just a program running on (presumably) a Windows computer.

Codec2 isn't geared to be a general-purpose codec. It's specifically geared to be a speech codec for extremely band-limited channels. It tries to be better than analog SSB, the target is legibility, not audio quality in the sense like music transparency, etc.

Re: xHE-AAC. Is it ready yet? Any encoders out there?

Reply #53
Guys, you're wasting your time on something that will not happen. xHE-AAC won't be publicly available.

Some good news,

ERLANGEN, Germany--(BUSINESS WIRE)--With the release of the Android P beta 3 preview, Fraunhofer IIS announces a new version of the popular FDK library which has been a part of Android since 2012. The FDK2 version will bring several new technologies to Android OEMs, service providers and developers, including xHE-AAC for video and music delivery down to 12kbit/s for stereo sound and MPEG-D DRC dynamic range control for better listening in noisy environments.

Finally it will be possible to do public listening tests comparing Opus and xHE-AAC. Also being open source, it will guarantee support for the codec regardless of its commercial future,

Re: xHE-AAC. Is it ready yet? Any encoders out there?

Reply #54
Hi, Ivan,

I should eat my own words now.  I admit it  :)

In other hand You  as developer know better than anyone else that everything will depend on encoder. 
FDK is known to be somewhat inferior to Apple and FhG (Winamp) (HE)-AAC encoders. Whether FDK xHE-AAC will be superior or not to extremely well tuned AAC encoders is still question.

Competition is welcome anyway!

Finally it will be possible to do public listening tests comparing Opus and xHE-AAC
Agree. Especially now when new version of Opus 1.3 will be released soon.

Re: xHE-AAC. Is it ready yet? Any encoders out there?

Reply #55
For me, it would be interesting to see how much impact in quality remains at such low bit-rates between "good enough" codec implementations where large part of the spectrum is parametrically generated, not transform-coded.

But for that we'd need more than one available implementation of xHE-AAC.

Re: xHE-AAC. Is it ready yet? Any encoders out there?

Reply #56
There's maybe also some potential to exploit temporal self-similarity. In music, many sounds are often repeated with minimal changes. Sometimes even without any changes (samples, techno, etc). 
So far I haven't heard of any codec which uses it and actually works.

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