[vorbis-dev] Using the vorbis psychoacoustics model

[Nyarlathotep]

Monty wrote:

> > I need a psychoacoustics model for some experiments and would like to use the
> > one included in vorbis. Is there any documentation about how to use it? Looks
> > like the relevent code is in psy.c, but I can't go further.
>
> The psychoacoustics in Vorbis are directly taken from two papers by R. Ehmer
> published in the Journal of the Acoustical Society of America in 1959.  They
> take the raw data for pure tone and noise masking (by band/dB) from those
> papers and apply them to the short-time MDCT spectrum of the input signal,
> finding a noise and tone masking curve for the input.  Later, I also apply an
> ATH cutoff.
>
> As for using that code, it it easily divorced from the rest of Vorbis.  You
> need psy.c/psy.h and the info_psy typedef from codec.h.  Transform functions
> from other modules may also be used; look at the includes at the top of psy.c.
>  It should all work outside of Vorbis without modification.
>
> > Also I would like to know whether I can be of any help in vorbis. I have some
> > knowledge in speech coding (I doing my master at the University of Sherbrooke's
> > speech coding lab) and I'm fluent in C/C++. I am not that familiar with "general
> > audio" coding.
>
> Get a feel for the code and let us know if you see something that needs doing
> (at this point, the majority of the work can be split into (a)API improvements
> (b) optimization (c) audio quality improvements in the encoder). Since you have
> a background in speech coding, I actually have some issues in LSP fitting I'm
> trying to solve right now.  You up to answering a few questions on LSP
> behavior?

mmmm Why aren't you using lames Gpsycho???

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