[Speex-dev] Double codebook

Björn Thalheim s9268716 at mail.inf.tu-dresden.de
Mon Jul 24 07:45:35 PDT 2006


Jean-Marc Valin wrote:
>> (I've seen the numbers 63, 45 and 171 being written into the stream very
>> often
> I do expect some to be more common than others, but I don't think it's
> only a handful of entries that get used.

I will have to examine the statistics of the codebook entries written
into the stream during my work anyways.
Maybe I'll find out something interesting, I can post that on the list
if I have any results.

>> Should I try at least
>> using -vad to reduce this redundancy (the less redundancy there is, the
>> better this is for my task, which is still a steganographic extension to
>> speex).
> I don't see what -vad would have to do with that... In any case, yes
> there is some redundancy.

For my test scenario, I will use
	speexenc --vbr [filename].wav [filename].spx
because that seems reasonable for many applications like hearing books,
podcasts etc. (I don't see a reason why a no-option call or a call with
option -n would be very reasonable)

> Speex uses VQ, but it doesn't use any form of
> entropy coding on the symbols. This makes it easy to get CBR, but of
> course, there's a bit of redundancy left (I would expect about 10%).

As I wrote above, this redundancy will be subject to my studies.

Thank you very much,


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