Vorbis successor

Hi all,

For those interested, this is a great page on the audio
codec called CELT, which is slated to replace Vorbis in
the future (the audio codec usually used with .ogg files).

http://people.xiph.org/~xiphmont/demo/celt/demo.html

Looks promising, and there are plenty of juicy details
on the psychoacoustic model.

-Carl

CELT is now Opus,

http://www.opus-codec.org/

the low-latency audio codec that beats all comers at
all bitrates

http://people.xiph.org/~greg/opus/ha2011/
http://listening-tests.hydrogenaudio.org/igorc/results.html

Impressive. -Carl

--- In tuning@yahoogroups.com, "Carl Lumma" <carl@...> wrote:
>
> Hi all,
>
> For those interested, this is a great page on the audio
> codec called CELT, which is slated to replace Vorbis in
> the future (the audio codec usually used with .ogg files).
>
> http://people.xiph.org/~xiphmont/demo/celt/demo.html
>
> Looks promising, and there are plenty of juicy details
> on the psychoacoustic model.
>
> -Carl
>

It turns out Opus handles low bitrates with a separate
codec (based on what Skype uses for voice), so maybe slightly
less impressive.

Unlike Vorbis, Opus is an IETF standard, so major browsers,
at least, will have to support it. -Carl

--- In tuning@yahoogroups.com, "Carl Lumma" <carl@...> wrote:
>
> CELT is now Opus,
>
> http://www.opus-codec.org/
>
> the low-latency audio codec that beats all comers at
> all bitrates
>
> http://people.xiph.org/~greg/opus/ha2011/
> http://listening-tests.hydrogenaudio.org/igorc/results.html
>
> Impressive. -Carl
>
> --- In tuning@yahoogroups.com, "Carl Lumma" <carl@> wrote:
> >
> > Hi all,
> >
> > For those interested, this is a great page on the audio
> > codec called CELT, which is slated to replace Vorbis in
> > the future (the audio codec usually used with .ogg files).
> >
> > http://people.xiph.org/~xiphmont/demo/celt/demo.html
> >
> > Looks promising, and there are plenty of juicy details
> > on the psychoacoustic model.
> >
> > -Carl
> >
>

Boy it's a good thing I didn't save my large music collection as .oggs.

> --- In tuning@yahoogroups.com, "Carl Lumma" <carl@> wrote:
> >
> > Hi all,
> >
> > For those interested, this is a great page on the audio
> > codec called CELT, which is slated to replace Vorbis in
> > the future (the audio codec usually used with .ogg files).
> >
> > http://people.xiph.org/~xiphmont/demo/celt/demo.html
> >
> > Looks promising, and there are plenty of juicy details
> > on the psychoacoustic model.
> >
> > -Carl
> >
>

--- In tuning@yahoogroups.com, "Billy" <billygard@...> wrote:
>
> Boy it's a good thing I didn't save my large music collection as .oggs.

Why? I do have a large Ogg Vorbis collection but I don't see how this is a problem. Could you explain more?

Keenan

>> Boy it's a good thing I didn't save my large music collection as .oggs.
>Why? I do have a large Ogg Vorbis collection but I don't see how this is a problem. Could you explain more?

Rough guess...if you decided to put all your music in a compressed format like OGG and decompress it so you can recompress it, you end up

A) Losing the quality involved in compression to OGG
and then
B) Losing the quality involved in compression to the new codec AKA CELT

If you just converted straight from uncompressed to CELT, you'd only get the quality loss in B) instead of A) and B)

--------------------
Side note, the real value in this format seems to be the low-latency, which makes it good for real-time online musical collaboration.  The actual compression ratio and sound quality seems/tests-as akin to AAC-Plus/AAC-HE, which came out some 7 or more years ago: nothing ground-breaking. 

   I wonder what happened to GHOST, xiph.org's intended direct competitor to AAC-plus.  Supposedly, it was designed to split a signal into both a noise and harmonic section (detecting root and overtones and so on), which seems to fall under http://en.wikipedia.org/wiki/Blind_signal_separation.  It begs the question once you are going through the trouble to detect the root tones and overtones, wouldn't it be possible to re-tune an entire compressed audio file upon decode by shifting the root and overtones to match an arbitrary Xenharmonic scale on the fly?  Now that would be fun...

________________________________
From: Keenan Pepper <keenanpepper@...>
To: tuning@yahoogroups.com
Sent: Friday, July 27, 2012 3:31 AM
Subject: [tuning] Re: Vorbis successor

 
--- In tuning@yahoogroups.com, "Billy" <billygard@...> wrote:
>
> Boy it's a good thing I didn't save my large music collection as .oggs.

Why? I do have a large Ogg Vorbis collection but I don't see how this is a problem. Could you explain more?

Keenan

On Fri, Jul 27, 2012 at 6:09 PM, RR <djtrancendance@...> wrote:
>
> >> Boy it's a good thing I didn't save my large music collection as .oggs.
> >Why? I do have a large Ogg Vorbis collection but I don't see how this is
> > a problem. Could you explain more?
>
> Rough guess...if you decided to put all your music in a compressed format
> like OGG and decompress it so you can recompress it, you end up
> A) Losing the quality involved in compression to OGG
> and then
> B) Losing the quality involved in compression to the new codec AKA CELT
>
> If you just converted straight from uncompressed to CELT, you'd only get
> the quality loss in B) instead of A) and B)

I dunno if Celt will support OGG so that there's some lossless way of
transcoding OGG to Celt, but it doesn't matter anyway. Applications
won't just drop support for OGG, so you'll be able to keep your OGG
files, but just start using Celt going forward for new things. It's
kind of like how the invention of AAC didn't require everyone to
transcode their MP3 files to M4A.

-Mike

--- In tuning@yahoogroups.com, Mike Battaglia <battaglia01@...> wrote:
> > Rough guess...if you decided to put all your music in a compressed format
> > like OGG and decompress it so you can recompress it, you end up
> > A) Losing the quality involved in compression to OGG
> > and then
> > B) Losing the quality involved in compression to the new codec AKA CELT
> >
> > If you just converted straight from uncompressed to CELT, you'd only get
> > the quality loss in B) instead of A) and B)

Right... which is why I wouldn't think of doing this. My music collection is in Ogg Vorbis and it's going to stay Ogg Vorbis. The fact that something better exists doesn't suddenly make Vorbis any worse, or not work anymore.

> I dunno if Celt will support OGG so that there's some lossless way of
> transcoding OGG to Celt, but it doesn't matter anyway. Applications
> won't just drop support for OGG, so you'll be able to keep your OGG
> files, but just start using Celt going forward for new things. It's
> kind of like how the invention of AAC didn't require everyone to
> transcode their MP3 files to M4A.

Right. Except note that "Ogg" is not a codec, but a container format like AVI. Also "CELT" doesn't exist anymore because it's been replaced by "Opus". So the correct thing to say is that my music collection is in Ogg Vorbis format, and there's no reason to convert it to Opus (whether Ogg Opus or ___ Opus). I'm just going to keep it Ogg Vorbis and this doesn't affect anything. Just like if I had an MP3 collection I would keep it MP3 and this also wouldn't affect anything.

Keenan