[vorbis-dev] vorbis-utils features ;)

[Michael Smith]

>Still shouldn't be needing 200 kbps to code this though; if it's below
>the threshold of hearing it shouldn't matter whether it's random or
>not; Vorbis should be throwing it out! Or is there a major mistake in
>the psycoacoustic model?

Vorbis models the threshold of hearing in a slightly different (and more 
accurate) way than many mp3 encoders. Here's a somewhat simplified explanation:

We don't know the playback level (someone might have their amp turned up REALLY
high), so a fixed threshold isn't possible. Instead, the threshold is a constant
level below whatever the current peak level is, more or less. So almost-silence
is encoded in a way not significantly different from full-level sound. The 
difference is that the almost-silence tends to be very close to noise, so it's
hard to encode (uses a lot of bits). It's neccesary to do this _because_ we
don't (and can't) know the playback level.

I might have got that wrong, having never actually read that bit of code, but
I think this is mostly correct.

Michael

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