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Topic: xHE-AAC vs HE-AACvE (Read 23255 times) previous topic - next topic
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Reply #25

You've said they all support Opus. I checked Apple for example and do not see Opus anywhere on this page: Supported Audio Codecs in macOS

Another one of the "big-four" also show nothing for Opus: Supported Codecs in Windows

Microsoft added Opus support in 2016, Apple in iOS 11.

Since AOM uses Opus for audio, everyone who isn't using HEVC has to implement it, and since HEVC is failing, Opus is becoming universal.  It will be interesting to see what happens with AAC once it is no longer required for video, particularly if they don't cut the license fees.


Reply #26
macOS High Sierra as well, but only if you pack it in a CAF container instead of Ogg, and the means to do so is undocumented, and the only tool on the OS that supports producing or encoding CAF Opus files only supports mono, and doesn't necessarily guarantee gaplessness.

I produced a patch against FFmpeg that supports encapsulating Opus into CAF containers, but it doesn't generate all of the headers that Apple's tools do, but the files decode nonetheless. The fact that it doesn't produce all the unknown headers, and that said headers are unknown, is why the patch was not accepted.


Reply #27
Thanks for the sample.
As I am currently on a Mac I do not have access to the Opus 1.3 beta but decided to go ahead with a test on 1.2.1.
First off, this is not an apples-to-apples comparison because it is very clear the radio station is processing the audio in a manner that emphasizes the presence region and bass.
Linked are three roughly time-aligned samples. One is the original lossless capture from Spotify (at the "Premium" quality). Another is Opus 1.2.1 encoded at 48kbps. Another is your xHE-AAC. It's very clear which one is your sample because of the aforementioned treble lift. However, they were loudness matched.
I do not notice any major sins of commission in the treble on the Opus encode.

Unfortunately we can not perform a true comparison until we can encode our own samples.

Hi Moni,

I checked out the Opus 1.3 beta Windows binaries offered. Then I remembered a much easier way to test Opus: Ladiocast on macOS (current version as of when I'm typing this is 0.12.4)! It has the Opus 1.2.1 release version of the codec. LadioCast is receiving the audio feed from the PC running the Optimod PCn1600 via Rogue Amoeba's Airfoil on the PC and Airfoil Satellite on the Mac (uses Apple AirPlay with Apple Lossless Codec streaming). So no compromise in audio quality getting the feed from the PC to the Mac and into LadioCast! I'm using a virtual audio device created in Loopback to direct the audio out of Airfoil Satellite to Ladiocast. That device is in 2 channel 32 bit floating point mode at a 48kHz sampling rate.

I've setup a test 40kbps average bit-rate 48kHz sampling rate live Opus stream (right now simulcasting MaxRadio.CA) and am listening to it with VLC on my Mac on my AKG K240 Mk II headphones. It sounds very good! I don't think it beats 40kbps xHE-AAC but I would put it in second place over any other 40kbps streaming codecs I've run.

I'm surprised at how good it sounds! Here is the URL of the test stream currently simulcasting my eclectic format station MaxRadio.CA:

I am hearing the occasional appearance by codec disrupter guy Artie Facts but aside from that Opus is very impressive for an open source codec. For my ears it doesn't currently match the astounding clarity of 40kbps xHE-AAC but maybe it'll catch up in a future version!

Let me know your thoughts on the test stream! I just checked and verified the stream also plays in VLC for iOS. I have not yet tested any other players.