[vorbis] masking problems in Vorbis beta?

[Monty]

> This page contains details of his analysis.
> 
>  "http://users.belgacom.net/gc247244/analysis.htm"

The only flaw in the analysis is attributing the problem to masking.  It's 
just a bug, and in a completely different place.

> Look at the `original signal' line to explain the low frequency cut
> off in the ogg analysis.

This is due to the short block mistriggers.  They can't represent strong, low
frequency signals well (ok, they *can*, but the codebooks I'm using lean the 
other way)

> Frequencies above 16 kHz and hard for most people to hear.  I don't
> really think that it matters for human ears.  These test are the type
> that anal retentive audiophile weenies like to do.

Yes, that's why the beta has a cutoff :-)  But, actually, the next release will
turn off this cutoff and trust the ATH masking curve for the high end.  That
way, with real sounds, the cutoff will usually be around 16kHz (like it should
be) unless there's an unusually strong signal that has a chance of being
audible.  ...and of course, it will look good in the tests :-)

> Examine his critic of the MP3 encoders.  His best test is with an
> actual song.  Although I would think that Ogg Vorbis would do better at
> pure tones, since it uses MDCT.  This is somewhat distressing to me.

Don't be distressed.  It's just a bug.  

Monty

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