[vorbis-dev] Vorbis packet #3, codebooks and their large size

[Dave, Anish]

Hi,

Am I correct in understanding that the codebooks are *not* adaptive during
compression?  I see that Packet #3 is written to the stream in the beginning
of the encode process with no modification.  If the codebooks are not
adaptive, then why are codebooks included in the stream at all?  Why not
pass the mode type (A or B or C...) instead of all the mode info and let the
decoder load it's own mode_A/B/C... tables.  Was it done for patent reasons?

The reason I ask is that vorbis becomes useless for small audio samples like
speech because there is always that ~10K overhead for packet 3.  With
hundreds of samples in memory (or disk), it becomes an issue.

Would we be breaking any patents if we modified the encoder and decoder to
pass just the mode type instead of the all the mode information (time_param,
floor_param, res_param, mapping_param)?

In the future (version 1.0) would the codebooks still be included in the
vorbis stream or will they eventually be part of both the encoder and the
decoder?

Thanks.
---------------------------
Anish Dave
Univ. of Waterloo
Comp Sci.

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