Skip to main content ↑ ↓
Topic: Opus 1.2 alpha (Read 16983 times) previous topic - next topic
0 Members and 1 Guest are viewing this topic.

Re: Opus 1.2 alpha

Reply #25 –
About half year ago I tried to compare mp3 and opus formats. I think that the 64kbps opus = with the 320kbps mp3.
I didn't hear different in stereo separate, or quality when I used bigger framerate. But I don't know what version was it, because I maked those files with Goldwave. My full result was:
320 mp3 64 opus   stereo
---------------
256 mp3 48 opus   less stereo
160 mp3 32 opus   even less stereo
---------------
96  mp3  24 opus   it's been almost mono
48-64 mp3  16 opus
32  mp3 12 opus
My question that my result is correct, and concern to all version? (The best is 64 VBR?) And that the quality change when I using VBR, CVBR, CBR, or just the filesize?

Re: Opus 1.2 alpha

Reply #27 –
Is there anyone building the libopus.dll variant of this? I would like to try this with foo_streamer.
WavPack -b4x4hc
Opus --cvbr --bitrate 256 --framesize 5
 

Re: Opus 1.2 alpha

Reply #30 –
Hi!
I was spectating here as a guest for a while. =)
And also have downloaded some binaries from here (love this place because it lets guests to download attachments).
Just now listened to some (trance) music encoded from lossless with Opus different versions, VBR 32kbps.

libopus 1.2-alpha2-15 improvement compared to libopus 1.1.3
Result: Great! Stereo is retained much, much better this time! Of course, this tuning has changed overall quality perception. Artifacts are more perceptible now. High frequency instruments spectrum suffer more. It's time to notice that 32kbps is very low bitrate. ;-)
From my experience, stereo coding is the primary weak spot of current release version (libopus 1.1.3). At higher bitrates (my choice is 96kbps) too. I hope you will update the release soon! I see the great potential in the Opus audio codec, and in you, developers!
And I hope this improvement has effect not only on 32kbps bitrate. ;-)  (have not checked yet)

Re: Opus 1.2 alpha

Reply #33 –
Thanks, NR

Re: Opus 1.2 alpha

Reply #34 –
I'm testing 1.2 Alpha @ 44kbps (ABR) for music streaming (with a dense multiband compressor preset, CHR radio like sound) and have to say, quiet surprised by the results. On speakers for background listening it's not bad at all. I can notice some roughness >10kHz, and the alternation of stereo image, but comparing it to 64kbps HE-AAC i still prefer these artifacts to SBR's. Previous versions of Opus produced some kind of metallic warbling in this bitrate range on the kind of electronic music I'm listening to.

Good job guys! :) I wonder if there's still any room for improvement.
WavPack -b4x4hc
Opus --cvbr --bitrate 256 --framesize 5

Re: Opus 1.2 alpha

Reply #35 –
Quote from: darkbyte on
Good job guys! :) I wonder if there's still any room for improvement.
Of course :) Have you tried encoding speech at 12-20 kbps? Fullband speech starts from 14 kbps!
Encode something @16kbps with Opus 1.1, then... just let Opus 1.2 alpha blow you away (at the same bitrate).
sox -e float -b 32 -V4 -D gain -1 rate -v 48000 norm -1
opusenc --bitrate 96

Re: Opus 1.2 alpha

Reply #37 –
Should I expect any music quality improvements at ~200 kbps bitrate?

Opus is great! Some thoughts on potential improvements

Reply #39 –
I've fully switched over to Opus at 116kbps VBR, for sound quality indistinguishable from the original FLAC. Great job!

I've also proposed an idea for further improvements to Opus at sub-80kbps bitrates here:
https://hydrogenaud.io/index.php/topic,113941.0.html

I think Ogg Vorbis still has the edge in bitrates around 75 to 85kbps due to it's more accurate rendering of high frequency detail (-q0.85, lowpass filter lifted to 20kHz). A more aggressive VBR mode targeting higher temporary bitrate boosts, specifically to help render transients above 15kHz, could really help provide that extra level of clarity while still keeping the average bitrate low.

Re: Opus 1.2 alpha

Reply #40 –
Quote from: Lumitopia on

I think Ogg Vorbis still has the edge in bitrates around 75 to 85kbps due to it's more accurate rendering of high frequency detail (-q0.85, lowpass filter lifted to 20kHz). A more aggressive VBR mode targeting higher temporary bitrate boosts, specifically to help render transients above 15kHz, could really help provide that extra level of clarity while still keeping the average bitrate low.

That's very interesting, it would explain why Vorbis performed better here: https://hydrogenaud.io/index.php/topic,112486.0.html

Re: Opus 1.2 alpha

Reply #41 –
Quote from: Phoenix1 on
Quote from: Lumitopia on

I think Ogg Vorbis still has the edge in bitrates around 75 to 85kbps due to it's more accurate rendering of high frequency detail (-q0.85, lowpass filter lifted to 20kHz). A more aggressive VBR mode targeting higher temporary bitrate boosts, specifically to help render transients above 15kHz, could really help provide that extra level of clarity while still keeping the average bitrate low.

That's very interesting, it would explain why Vorbis performed better here: https://hydrogenaud.io/index.php/topic,112486.0.html

That makes sense, the most obvious artifacts with Opus happen when there's lots happening in the high end - high frequency details tend to smear and distort much more easily when competing with other high frequency noise (a tail of a cymbal crash in your case). I'm surprised you can hear it at 128kbps (VBR?) but I've definitely noticed that the attack on rides and hi-hats can sound softer in busier tracks even at 112kbps, but moving up by 4kbps seems to provide just enough bits to fool my ears (in my case at least). I might have to do more tests at my current bitrate to see if I can trip it up. But you can imagine how obvious the difference becomes when you compare Opus and Vorbis at below 80kbps. I was surprised by the results because I kept hearing that Vorbis was basically made obsolete by Opus - I really don't think that's quite true, yet - but with some tweaks I think it can be achieved. Apart from inaccurate treble, everything else already sounds great.

Re: Opus 1.2 alpha

Reply #42 –
Having said that, there are plenty of scenarios where Opus clearly sounds better than Vorbis at lower bitrates, especially electronic music (cleaner rendering of upper-mid detail / transients, a more convincing stereo image, and a lack of any of the pre-echo that Vorbis suffers from - which results in better attack and impact on things like snares and kicks). Artists like Infected Mushroom and Savant have music with lots of upper-midrange detail that really play to Opus' strengths, whereas Vorbis often sounds like a poorly encoded 112kbps MP3 at the same bitrate (~75kbps). It's cases like these where the difference really is night and day.

So Opus is already excellent at clean sounding reproduction - it really just needs a couple of extra VBR options that more aggressively assigns bits to high freq detail like I mentioned previously. Especially useful would be a new VBR mode based on the current "Constrained VBR" option - keeping the bitrate within a small range in most cases, but liberally assigning extra bits only when it detects high frequency detail. CVBR behaviour for everything under 15kHz, unrestrained VBR for detail above 15kHz.

Re: Opus 1.2 alpha

Reply #44 –
The x86 files : 4/16/2017
The X64 files: 4/2/2017

Re: Opus 1.2 alpha

Reply #46 –
Quote from: ziemek.z on
Quote from: darkbyte on
Good job guys! :) I wonder if there's still any room for improvement.
Of course :) Have you tried encoding speech at 12-20 kbps? Fullband speech starts from 14 kbps!
Encode something @16kbps with Opus 1.1, then... just let Opus 1.2 alpha blow you away (at the same bitrate).
I have been converting podcasts and similar content to VBR 18kbps, and the results are remarkably clear - even musical interludes sound listenable (albeit in mono). It actually sounds better than many of the FM radio stations here in the UK! I'm using the latest experimental build (1.2-alpha2-31-g8e19536b) - very impressive. A huge improvement on whatever version of Opus is bundled with "Switch Audio File Converter v5.19".

Re: Opus 1.2 alpha

Reply #48 –
Quote from: NetRanger on
Opus-tools v0.1.10-1-gd0dc36b (using libopus 1.2-alpha2-31-g8e19536b)
https://git.xiph.org/?p=opus.git;a=summary
https://git.xiph.org/?p=opus-tools.git;a=summary

I would just like to thank you for taking the time to provide updated binaries here. I'm a fan of Opus, and audio compression codecs, and music in general, so it's a big deal for me to be able to follow the latest updates to Opus. Thanks!

(As an aside, when will Opus 1.2 ever get out of alpha stage? XD )

Re: Opus 1.2 alpha

Reply #49 –
I wonder which codec is being used with --bitrate 32 --framesize 60 --cvbr --downmix-mono setting right now in 1.2-alpha. Seems like a nice spot for very low bitrate generic music. It's still noticable not transparent, but artifacts are not utterly annoying (at least compared to HE-AACv1 mono at this bitrate). For me it's even listenable with headphones on. But it sounds a bit different, like it was using SILK instead of CELT. 

Not closely related, but is there any algorithm which can more gracefully downmix stereo to mono in order to avoid phase cancelation as much as possible? Does Opus involves anything like that with --downmix-mono, or it's just using a simple downmix algorithm? Imo below 48kbps Opus is not capable enought to represent stereo without nasty artifacts at the moment (especially bad when played back on single speaker devices, like mobile phones), so I'm preferring the mono downmix. But that's just my 2 cents. Maybe reducing the stereo width and phase significantly before encoding could help, but then again, you can just downmix to mono then.
WavPack -b4x4hc
Opus --cvbr --bitrate 256 --framesize 5
 
SimplePortal 1.0.0 RC1 © 2008-2018