Dubber and others may be interested in responses from "Monty", the original brain behind the Vorbis codec. I brought up AACplus for discussion on the Vorbis mailing list. It sounds like Ogg Vorbis is far from beaten.
> Most say that a 48kb/s AACplus sounds better than a 128kb/s MP3,
That's claiming a bit much. Even against the original Blade (MP3 encoder) this
would require not paying much attention. What's true is that the
artifacts sound very different, so if you're listening for mp3-like
high-end problems, you probably won't hear them.
> which would put Ogg Vorbis at around 96kb/s IMO.
Not really. 64kbps Ogg is still a little better than the 48kbps
AAC+SBR we're talking about.
That's not to say the low bitrate AAC+SBR isn't very good; as a new
codec, it's quite an improvement to classic AAC at low bitrates. But
many of the press-release claims are (understandibly) pushing the
envelope of what is really believable.
Also, it's absolutely true that at the lowest bitrates (32/48kbps)
AAC+SBR currently has a decent edge over Vorbis low bitrate. Everyone
is still moving forward and the lead changes back and forth. The low
bitrate race is pretty much down to new AAC and Ogg these days. At
low bitrate, AAC is ahead, at mid-bitrate Vorbis is still leading.
> Is there anything that can be done to bring Ogg Vorbis up to this type of
> quality in the future, or is it about as good as it's ever going to be?
Of course. Development of these things tends to move forward in
bursts. I've done little Vorbis research work since 1.0 as there have
been other things to do. I'll get back to it if only because it's
what I'm best at and audio codec research feels good ;-)
> I would rather use patent free and open codecs, but this type of bitrate
> saving, particularly for streaming, cannot be ignored, and I'm concerned
> that this will slow the uptake of Ogg Vorbis and may reverse it's
> popularity in time.
The bitrate savings isn't as big as you fear and we'll take the lead
back again. Everyone is improving. Who would have ever thought back
in '98 that LAME would get as good as it is today? I'm curiously
surprised that AAC hasn't moved forward farther than it has...
Monty
And here are some more responses from Monty
That's claiming a bit much. Even against the original Blade (MP3 encoder) this
would require not paying much attention. What's true is that the
artifacts sound very different, so if you're listening for mp3-like
high-end problems, you probably won't hear them.
> which would put Ogg Vorbis at around 96kb/s IMO.
Not really. 64kbps Ogg is still a little better than the 48kbps
AAC+SBR we're talking about.
That's not to say the low bitrate AAC+SBR isn't very good; as a new
codec, it's quite an improvement to classic AAC at low bitrates. But
many of the press-release claims are (understandibly) pushing the
envelope of what is really believable.
Also, it's absolutely true that at the lowest bitrates (32/48kbps)
AAC+SBR currently has a decent edge over Vorbis low bitrate. Everyone
is still moving forward and the lead changes back and forth. The low
bitrate race is pretty much down to new AAC and Ogg these days. At
low bitrate, AAC is ahead, at mid-bitrate Vorbis is still leading.
> Is there anything that can be done to bring Ogg Vorbis up to this type of
> quality in the future, or is it about as good as it's ever going to be?
Of course. Development of these things tends to move forward in
bursts. I've done little Vorbis research work since 1.0 as there have
been other things to do. I'll get back to it if only because it's
what I'm best at and audio codec research feels good ;-)
> I would rather use patent free and open codecs, but this type of bitrate
> saving, particularly for streaming, cannot be ignored, and I'm concerned
> that this will slow the uptake of Ogg Vorbis and may reverse it's
> popularity in time.
The bitrate savings isn't as big as you fear and we'll take the lead
back again. Everyone is improving. Who would have ever thought back
in '98 that LAME would get as good as it is today? I'm curiously
surprised that AAC hasn't moved forward farther than it has...
Monty
And here are some more responses from Monty
> Now if that is true, technically it would be possible to use the same
> technics (SBR and PS) added on Vorbis OGG.
No, because the specific SBR extensions are part of the MPEG patent
pool. As it is, the current/future direction of Vorbis is to move
away from a pure transform-domain encoding anyway. SBR would still be
applicable, but some of the same mechanics would be built into the rep
model.
SBR's fundamental basis is 'each octave is closely related to the
octave below it'. It then implements something akin to an 'exciter'
that represents most of the upper part of the spectrum as a parametric
set of harmonic duplications of the lower octaves.
The basic idea is both sound and one that's been underexploited (upper
octaves are often harmonic duplications of lower octaves). One can
take advantage of that without using SBR, and that's the direction I'm
going. But there's more than the harmonic structure here; if strong
tones (the harmonic structure) of the audio is subtracted out, and
you're only looking at the leftover 'noise' in time, the subband
correlation is very strong in time as well. I don't know if
AAC(classic)'s Temporal Noise Shaping is also exploited by the SBR
extensions in any way, but I certainly plan to exploit that fact in
future Vorbis.
Monty
> technics (SBR and PS) added on Vorbis OGG.
No, because the specific SBR extensions are part of the MPEG patent
pool. As it is, the current/future direction of Vorbis is to move
away from a pure transform-domain encoding anyway. SBR would still be
applicable, but some of the same mechanics would be built into the rep
model.
SBR's fundamental basis is 'each octave is closely related to the
octave below it'. It then implements something akin to an 'exciter'
that represents most of the upper part of the spectrum as a parametric
set of harmonic duplications of the lower octaves.
The basic idea is both sound and one that's been underexploited (upper
octaves are often harmonic duplications of lower octaves). One can
take advantage of that without using SBR, and that's the direction I'm
going. But there's more than the harmonic structure here; if strong
tones (the harmonic structure) of the audio is subtracted out, and
you're only looking at the leftover 'noise' in time, the subband
correlation is very strong in time as well. I don't know if
AAC(classic)'s Temporal Noise Shaping is also exploited by the SBR
extensions in any way, but I certainly plan to exploit that fact in
future Vorbis.
Monty
> But, at its best, with an 'average' bit rate of 128kbps, mp3 should easily beat 48kbps aacplus. (Even at 128kbps cbr, I'd expect it to beat aacplus!)
Yes, add me as a 'me too' :-)
A decent 128kbps encoder should hand AAC+SBR its ass on a platter.
Respectable 128kbps mp3 encoders are very good today. "Something is
wrong".
> But at lower 'streaming radio' rates, no, Vorbis isn't the best. It
> wasn't tuned / designed for those rates.
> Roberto's 32k rate listening test didn't show Vorbis in a good light... I
> doubt a 48k test would be much different.
>
> Also, I faintly remember there were some comments after the test.
>
> I think that maybe they used some poor settings or some resample issues or something. The result was that vorbis might not have been at its best.
Speculation aside, I would not have expected Vorbis to fare well at
32kbps. It simply wasn't tuned/designed for it. Vorbis (as it is
now) was designed to scale down to ~64kbs at a time when mp3 wasn't
yet respectable below 192kbps. Today's AAC is not actually the same
codec as the AAC everyone remembers from three years ago; they're
different, related but incompatable codecs taped together in a new
package under the original name. No worries, we will update Vorbis
similarly and keep the same name so no one knows the difference :-)
Monty
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