[Vorbis] AACplus

[Borphee]

Ross;

> The listeners I mentioned were comparing MP3 128k streams and 48k AACPlus 
> streams from the same organization.  They have several streams running, and 
> the input audio is the same.

It's possible some of it could just be the settings used for the mp3 stream.

First, it's probably CBR, instead of vbr or abr.

They may have also added a low pass filter switch.  Or resampled.  Or forced 'true stereo'.  Or no telling what.

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!)


>> 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.

But I didn't pay much attention at the time because I didn't care about 32kbps.
 
> It is the low bitrates that I'm concerned about, and streaming radio is 
> concerned with, so the 1 million dollar question is:  Is it possible that 
> Vorbis can be tuned in a substantial way to sound anywhere close to AACPlus 

I would suggest you try some of the newer versions of Vorbis.  And perhaps some of the other versions that have been tuned by people other than Xiph.

Also, there was a bug in the resampling in some previous versions of Vorbis.  I don't remember if Roberto's test used that or not.  I suspect it might have, which might partially explain the poor results.  (Because in Roberto's listening tests, even a simple lowpass version (no encoder, just a 7khz lowpass filter) did as well as Vorbis!)

Where as AACPlus (and others) have tuned the lower bitrate settings, you'll have to experiment yourself with some of this with vorbis.  Such as the quality settings, whether to resample to 22khz, low pass filters, and so on.


> at low bitrates.  I currently stream a 28-32kb/s mono Vorbis stream using 
> 44khz, q=-2, but I've heard an AACPlus 32kb/s stereo stream and it sounds 
> much better, Much more highs.

I'd suggest trying to resample to 22khz.  And maybe play with some of the lowpass filters or such.


But I would say that at this point, Vorbis is probably not going to give results as good as AACPlus (or possibly even mp3pro).  It just hasn't been worked on as much as those codecs have.

Some you can do yourself by experimenting with the settings.  Other improvements will have to be done in the encoder.