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1) What is algebraic
celp is
a Code Excited LP
There are some kind of code,
and we can express code in some ways
A traditional code is
L-level code book calculated vector quantizer
but this method is need many
bits..and not so good
So people develope other
method...
That's algebraic code.
This is not need
codebook.
We just simulate +1 -1 pulses at every position ( in case of G.729, 40
position)
The important point is how position is
determined.
The positions grouped as track,
in G.729 track 0 is
0,5,10,....35 position
track 1 is 1,6,11......36
etc..
And each track have some pulses..These
pulses move only their track..
The best
algebraic combination of these pulses in each track is
selected..
2) tilt
compansation
The synthesised speech is passed through postfiler, which is
consist of LPC filter.
The frequency respons of this
filter is declined...
This slope affect spectrum of
speech..
So compansation is needed..by slope up
more details,
refer
IEEE TRANSACTION ON SPEECH AND AUDIO PROCESSING. VOL 3, NO. 1,
january 1995
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Algebraic codebook
Started by ●October 18, 2000
