[vorbis-dev] Psychoacoustic model

Johannes Sandvall js at sandvall.nu
Thu Feb 5 01:33:05 PST 2004



We've implemented a vorbis decoder based on Tremor and as part of the
documentation we're also writing about psycho acoustic models and
encoding.

We're quite up to date with the decoding process and psycho acoustics
in general but unfortunately not on the psycho acoustic encoding used
in Vorbis.

We have a few questions that would we would be very thankful to have
answer to:

Which tricks are used?

Critical bands model?

Noise masking noise?

Tone masking noise?

Noise masking tone?

Temporal masking?

Other aspects of decoding:

Are the codebooks fixed for VQ encoding and huffman for a given
quality?. Adjustments of VQ codebooks based on the audio or picking
a fixed codebook that minimizes the quantization error?

Regards Johannes Sandvall, Erik Montnemery
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