[Icecast] Re: [Vorbis] AACplus

Monty xiphmont at xiph.org
Tue Mar 1 21:42:07 UTC 2005

Others have already chimed in, and I thought I could resist, but I
guess I can't...

> I'm seeing more and more streaming stations using AACplus, with many 
> listeners being amazed at the sound quality.  Most say that a 48kb/s sounds 
> better than a 128kb/s MP3,

That's claiming a bit much.  Even against the original Blade 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...  


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