Subject: Re: 3D Audio -improving HRTF filtering From: Jose-Javier Lopez <jjlopez@xxxxxxxx> Date: Wed, 5 Apr 2006 20:04:35 +0200Hi Fred, Off course, any kind, is that I wanted to say (or rectangular windowing, that is the same). Windowing is indicated for signal analysis and other DSP things, but not for fast convolution using FFT. JJ ----- Original Message ----- From: "Fred Herzfeld" <herzfeld@xxxxxxxx> To: "Jose Javier Lopez" <jjlopez@xxxxxxxx> Sent: Wednesday, April 05, 2006 7:15 PM Subject: Re: 3D Audio -improving HRTF filtering > Hi Jose, > > I agree that a Kaiser window should not be used, in fact for any kind of > accurate results no window at all shoud be used. Why did you single out > Kaiser? > > Fred > > Jose Javier Lopez wrote: >> Do not window input samples with kaiser !!!!!!!!!!!!!!!!!!! >> >> Review overlap-add or overlap-save algorithm in "Oppenheim - >> Distrece-Time Signal Processing". >> >> or look for code examples on Internet. >> >> JJ >> >> >> ----- Original Message ----- From: "sherin tech" <sherin.tech@xxxxxxxx> >> To: <AUDITORY@xxxxxxxx> >> Sent: Wednesday, April 05, 2006 11:38 AM >> Subject: [AUDITORY] 3D Audio -improving HRTF filtering >> >> >> Hi all, >> >> I am working on 3D-Audio based on HRTF filtering. >> >> My starting point is KEMAR data from MIT media labs, done by bill >> gardner and Keith Martin. >> >> I have implemented a basic by referering to the demo SGI code provided >> in MIT site. >> >> My first implementation is just time domain convolution , which works >> wothout any noise. >> >> >> But for efficient implementation I am trying to move to frame based >> processing, as in the SGI code provided in the MIT website. >> >> the steps involved in my new implemantation are ... >> >> 1) take 1024 number of samples. >> 2) Window those 1024 samples. (for this I am now using kaiser window of >> beta=16) >> 3) Take 1024 point FFT the input >> 4) Zero pad the 128 point HRTF filter to make it 1024 point. >> 5) Take 1024 FFT of HRTF Left ans Right data. >> 6) Multiply the spectrum in frequency domain. >> 7) Take 1024 point IFFT of the resultant spectrum. >> 8) Do a 75 % overlap and add. >> >> >> But a minor amout of noise is present in the o/p .... >> >> As a general instruction ... how can I improve the SNR of the o/p ????? >> >> I have tried , diferent type of windows, and overlap of 50 % also .. >> >> Any lights in to this ... ???? >> >> regards, >> sherin >> >> >> > > > -- > Fred Herzfeld, MIT '54 > 78 Glynn Marsh Drive #59 > Brunswick, Ga.31525 > USA >