Vorbis dev - Aug 2009 - VQ and Huffman codebooks creation

Hello,

I'd like to know in detail how does the creation of VQ and Huffman codebooks
work in Vorbis. I've used the source code from *encoder_example* as guide,
but the only reference I've found is the function *_make_words *inside *
vorbis_book_init_encode*, which creates the Huffman tree if I'm not wrong.
So I have two doubts. The first is that, for creating the Huffman tree (and
also the VQ codebooks), should be necessary some kind of histogram, and I
don't find when nor where it is created (*_book_init_encode* is called
before reading the audio data stream). Secondly, I don't find where (in the
source code) or when (in the encoding process) are the VQ codebooks created.
I don't know if, as VQ is optional in Vorbis, may be
*encoder_example*doesn't use it (it is an example after all), or if I
have missed something.
I suppose the VQ codebooks are created with some function within the
*vq*folder, but I don't find any reference to them within
*encoder_example*.

Any help will be much appreciated.

Thanks,

Jes?s
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On Sun, Aug 16, 2009 at 9:09 AM, Jes?s D?az
Vico<jesus.diaz.vico at gmail.com> wrote:
> I suppose the VQ codebooks are created with some function within the
> vq folder, but I don't find any reference to them within
encoder_example.
In the libvorbisenc implementation the codebooks are pre-generated
based on training data, and a set are selected based on the quality
setting.

There are a number of untilities in the vq folder to help with
codebook generation, but they're not themselves part of the library.
That's why you don't see them called from encoder_example. The actual
books are compiled in from files in the lib/books/ set of folders, and
chosen based on the mode configurations in lib/modes/.

HTH,
 -r