[Speex-dev] Exc CB Search very little Question

[Björn Thalheim]

Hi,

Jean-Marc Valin wrote:
> Well, you could change the order in the encoder as long as you reverse
> it in the decoder as well.

Ok, I see that in the split_cb_shape_sign_unquant function, that each
coefficient is tied to it's position in the nb_subvect exc coefficients.

Honestly, I have problems understanding what exactly the codebook search
works like. If you have the time to to that, Jean-Marc, I would
appreciate some hints on the following:
1. What is the point in multiplying a codebook index with some number
ant adding a loop variable to it as done in the exc unquant function.
   for (j=0;j<subvect_size;j++)         	
      exc[subvect_size*i+j]+=s*0.03125*shape_cb[ind[i]*subvect_size+j];
2. How does the CB search function split_cb_search_shape_sign work? I
know the parameter N defines the number of candidates for each of the
nb_subvect CB line numbers which are later on written into the stream.
But especially, how the best_ntarget list is being updated, I am a
little clueless.

Regards,

Björn


PS: for me personally, I'd like to know how to change the cb id found
while keeping the error introduced by this low.

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