Vorbis - Nov 1995 - Vorbis Codebooks

Hello, 

Vorbis uses codebooks,  for example to do vectorquantization and
huffman-encoding.

My question is - are all these codebook dynamicly generated
("trained")

or are there also static codebooks used ?

If yes, what specific tasks are these 2 types used for, during encoding ?

 

Thanks

Stoffke

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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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