[Clam-devel] Spectral Analysis/Synthesis

[Xavier Amatriain]

Comments below...
> Configure-Stuff:
>   
I can't see anything wrong with configuration but I am wondering... why 
did you decide to use KaiserBessel35??

> This is the way I create the temporary buffer in WindowSize (package is a 
> CLAM::Frame) :
>
> Analysis:
> CLAM::Audio tmpAudio;
> tmpAudio.SetSize(package->frameSize()*4);
> CLAM::TIndex index = (package->frameSize()*2)-(package->frameSize()/2);
> tmpAudio.SetAudioChunk(index, package->GetAudioFrame());
>   
Wait! index is constant? That means you are using some sort of zero 
padding but then not
removing it properly at synthesis. What you should do is concatenate all 
the frameSize samples
you get into your tmpAudio until you got enough to send it to the 
analysis (i.e. do it four times and then
start sending). After that, you need to append the new frameSize samples 
at the end of your buffer while
keeping the last frameSize*3 before those.
> this->_specAnal.Do(tmpAudio, package->GetSpectrum())
>
> Synthesis:
>
> CLAM::Audio tmpAudio;
> tmpAudio.SetSize(package->frameSize()*2);
> 	
> this->_specSynth.Do(package->GetSpectrum(), tmpAudio);
> this->_overlapAdd.Do(tmpAudio, package->GetAudioFrame())
>   
Also this is not correct :-( You can't just take the first frameSize*2 
samples and feed them to the OLA.
You need to take the center frameSize*2. Else the inverse window you are 
applying does not correspond to
the one you applied in the analysis (in terms of where the center is).

Hope it helps!