[Speex-dev] Exc CB Search very little Question

Björn Thalheim s9268716 at mail.inf.tu-dresden.de
Tue Sep 19 05:36:45 PDT 2006


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++)         	
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.



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

Many a writer seems to think he is never profound except when he can't
understand his own meaning.
		-- George D. Prentice

Important! Please recognize my new GPG Public Key!
                 Björn Thalheim
gpg fingerprint: 2F22 AAEB 1818 1548 EC78  1AE8 9D2E FCB4 0980 28CC
   download key: wget http://www.ifsr.de/~bjoern/gpg/public_key.asc
       See also: http://www.ifsr.de/~bjoern/gpg/key.html

-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 252 bytes
Desc: OpenPGP digital signature
Url : http://lists.xiph.org/pipermail/speex-dev/attachments/20060919/b7bf65d5/signature.pgp

More information about the Speex-dev mailing list