It's been said that Opus is superior to AAC at low bitrates and I'm curious what that means. What bitrate, for example, would Opus need to provide roughly equal sound quality with an AAC (HE-v2) track encoded at 48 kbps?
I can only provide some of my old personal tests.
48 kbps.Warning: This was Opus 1.2 early alpha. 1.2.1 final version contains some very important improvements.
I compared it with FhG HE-AAC (latest Winamp) encoder which was the best encoder at 32-48 kbps according to my internal tests (until Opus 1.2 has appeared)
Scores:
Opus 1.2 early alpha -
3.68FhG HE-AAC -
3.41 FhG HEAAC Opus 1.2a LBR TUNE
01 Castanets 2,5 3,6
02 fatboy 2,6 4,5
03 eig 2,6 4
04 bachrprichord 4,1 3,6
05 enola 3,8 3
06 trumpet 4,1 4,1
07 applaud 3,7 3,4
08 velvet 2,7 2,8
09 linchipin 3,5 3
10 spill 4 3,5
11 female speech 4,3 4,8
12 french ad 3 3,9
Average Score 3,408 3,683
32 kbps.Again, only Opus 1.2 alpha results. Not final 1.2.1.
I have compared to FhG HE-AACv2 again but now at ~32 kbps VBR.
Scores:
Opus 1.2 alpha -
3.22FhG HE-AACv2 -
2.92 Link https://hydrogenaud.io/index.php/topic,114234.msg941691.html#msg941691
P.S. You can make your own tests and share them here.
Thank you, that's very helpful.
And forgive me for being obtuse, but are higher numbers better here? And does the standalone OpusEnc encoder produce different results than the one in the latest ffmpeg?
Higher is better.
Ffmpeg can use either libopus or it's experimental native decoder. You want to use libopus.
Thank you, that's very helpful.
And forgive me for being obtuse, but are higher numbers better here?
You're welcome.
Yes, "1" means very annoying, "5" - impercetbile. Like here https://hydrogenaud.io/index.php/topic,100896.0.html
http://i44.tinypic.com/2133c6c.png
Also I highly suggest to perform your own tests because results vary a lot for different listeners, hardware and preferments.
I.e. I have performed the same test but on speakers (previous tests were made on headphones) on Opus vs HE-AACv2 at 32 kbps and both were on par. Seems like artifacts of parametric stereo are more forgiving on speakers.
All in all, HE-AACv2 and Opus are in the same league at 32 kbps VBR. More tests are needed.
While Opus has an advantage at 48 kbps and higher.