[Speex-dev] how is the fixed codebook generated

tunkeat tunkeat at gmail.com
Tue Jan 18 19:05:42 PST 2005


thanks for the speedy answers and for speeding
my understanding of the celp.  have some questions
on the forming of the fixed code book

1) fixed codebook
I understand that the residual, after removing sample-to-sample
and periodic redunancies, when properly normalised is noiselike
and gaussian-like.  if i understand correctly, the codebook 
consists of a wide, relatively constant spectrum TO ensure
Glottal pulse shaping. what is glottal pulse shaping? (synthesized
output will sound like glottal utterances?) 

In addition, to the constant spectrum requirement (I understand that
to be the codes are pseudorandomly generated), i read from fs 1016 
that the code words are overlapped by a shift of -2.  what is the idea
behind this? just briefly, how are the fixed codewords in speex generated?

finally, are these fixed codes, after passing through the
synthesized filter, supposed to produce those unvoiced segments of speech
and also the "noise component" in voiced segments?  is the output called 
fricative noise in psychophysics?

can anyone recommend a book that explains the basics of celp (more on the
ideas, not just how it is done) for beginners?


More information about the Speex-dev mailing list