[vorbis] Vorbis Codebooks

Michael Smith
2003-05-08T02:51:59Z

On Sunday 04 May 2003 16:31, stoffke@directbox.com
wrote:
> Hello,
>
> Vorbis uses codebooks,  for example to do vectorquantization and
> huffman-encoding.
>
> My question is - are all these codebook dynamicly generated
("trained")
>

Sort of. The codebooks are trained 'offline'. For a given libvorbis
release,
they're effectively static - but because the format doesn't specify a
set of
static codebooks, the books used by the encoder are efficiently packed into
one of the vorbis header packets. An encoder is free to use any codebooks it
wants to - it can, if it so chooses, do fully-dynamic training of the books
(though that obviously doesn't work with single-pass encoding, and the
overhead isn't all that likely to be worth it).

Mike

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