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Discussion Groups | Audio Signal Processing

Technical discussions related to Audio Signal Processing (digital effects, acoustics, noise reduction, musical signal processing, etc).

Search Results for "fft"

  

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Extracting SNR from FFT   [3 Articles]

je0062002 - Aug 8 2007
Dear All Does anyone here already coded a SNR computation from FFT bins ? I already coded a FFT algo in C, it is ok, but I cannot succeed in coding a SNR extraction from the FF... Extracting SNR from FFT

[general] arm fft doubt

Abhishek Ballaney - Oct 29 2007
dear all, we need to use fft algo. for arm9e processor. we got it from: http://www.lartmaker.nl/projects/fft-arm/ but we aren't able to build it in windows (codewarrior), a... [general] arm fft doubt

FFT on a narrow band   [4 Articles]

Jean Viljoen - Nov 3 2003
Does anybody know if it is possible to calculate a FFT on a certain bandwith, less that the sampling frequency? For example: I only have the resources to do a 64 point FFT, b... FFT on a narrow band

zeroing the FFT   [33 Articles]

Suciu Radu - Oct 23 2001
I have an FFT algorithm that works for example only for 1024, but I have only , say 900 discrete values to calculate the FFT on. I put the other 124 values to zero (from positi... zeroing the FFT

16 bit Fixed point FFT

chetanbs77 - Feb 20 2006
Hello, I have a query regarding 1024 point FFT implementation with 16 bits input data( real and imagainary) and the twiddle factors are also 16 bits(real and imaginary). The a... 16 bit Fixed point FFT

Hann windowed FFT from 'rectangular' one ?   [7 Articles]

prze...@wp.pl - Aug 19 2006
Hello, This is my first post in this group so let me say hi to everybody :) ... and of course I have a question, probably simple but ... (how) can I get hann-windowed comp... Hann windowed FFT from 'rectangular' one ?

Block Floating point FFT or 32 bits precision FFT ?   [2 Articles]

Curl - Dec 5 2001
Hello ! Sorry, this is my second question in two days .. I'd like to know if someone tried this two algorithms : Block Floating point FFT and 32 bits (double precision) FFT.. ... Block Floating point FFT or 32 bits precision FFT ?

FFT precision   [5 Articles]

Curl - Nov 27 2001
Hello My question may be stupid.. I have overflow problem with 16bits IFFT (inverse transform) In audio applications : Is FFT precision at least 32 bits ?? Or (in other words)... FFT precision

FFT's   [4 Articles]

John Skurka - Mar 3 2005
Hey all: I'm a newbie here, and have a FFT related question. Some background first. I've written a VB program that takes an FFT of a time function comprised of fixed puls... FFT's

a MPEG2 question

ZiP HE - Nov 28 2000
Dear all, I am a newcomer in DSP, and now working on MPEG-2 Audio Encoder. In ISO11172-3 encoding algorithms(Layer II and Layer III), before FFT transfer, there are 1152 sample... a MPEG2 question

how to comput 2N point array by using N point fft?

diao...@126.com - Mar 20 2006
everyone: hi. I want to save time in the process of fft,I know there is one method of using a complex N point fft to comput a real 2N point array.But I dont know how to do... how to comput 2N point array by using N point fft?

RE : how to comput 2N point array by using N point fft?

Sigmund Gudvangen - Mar 21 2006
Even better, use a RFFT, i.e. a FFT that takes a real-valued input vector, of length N, and computes only N+1 of the (complex) output values: X(0), X(1), ..., X(N/2). The real valu... RE : how to comput 2N point array by using N point fft?

RE : how to comput 2N point array by using N point fft?

Sigmund Gudvangen - Mar 23 2006
Ooop, in the phrase "computes only N+1 of the (complex) output values:", N+= 1 should be N/2+1. Sorry. Subject: RE : [audiodsp] how to comput 2N point array by using N point ff... RE : how to comput 2N point array by using N point fft?

Frequency response using FFT   [2 Articles]

joon...@jippii.fi - Jan 18 2007
I try to get a frequency response using FFT(output)/FFT(input). My input signal is white noise. This works pretty good in low frequency. However in high frequency (next to the samp... Frequency response using FFT

Re: Digest Number 442

Andrew Nesterov - Aug 24 2006
Hi PrzeM, Yes, it is very possible to calculate the window-modified spectrum, which is a convolution of the data spectrum and the window spectrum. However, the temporal wind... Re: Digest Number 442

Amazing PRBS   [5 Articles]

joon...@jippii.fi - Mar 24 2007
This question is not a real problem. It is just something which makes my head so confused and I really need a relief :) I tried to get a frequency response of an unknown system... Amazing PRBS

Impulse Testing the FFT   [13 Articles]

ShadowsEdge Admin - Feb 27 2005
Greetings, I have been experimenting with several FFT routines and none of them seem to work like they are supposed to. From what I understand of the theory, an impulse in th... Impulse Testing the FFT

coherent/incoherent gain of fft window

Johan Nilsson - Feb 6 2003
Hi I'm right now dealing wiht calculation of signal to noise ration from an fft transform. Specificly I would like to know more about the coherent and incoherent gain of a fft... coherent/incoherent gain of fft window

FFT Sample Data - Whats wrong with this ??   [6 Articles]

ShadowsEdge Admin - Feb 28 2005
Greetings, Here is a sample of the kind of data I've been getting. This kind of result is common to all the FFT routines I have tried. The fact that I have tried 3 different... FFT Sample Data - Whats wrong with this ??

FFT and EQ   [6 Articles]

2spo...@informatik.uni-hamburg.de - Oct 20 2005
Hello, I have a short question for you. I am working with blocks of audiosamples which will be calculated like this. Audiosamples-in -> windowing -> FFT -> iFFT -> windowing -... FFT and EQ

DFT-based Filtering: does it matter if I normalize by N in the FFT or iFFT?

rger...@ea.com - Aug 30 2005
Hi all, and apologies in advance for the long-winded question. I have recently implemented a fast convolution algorithm using the FFT/iFFT to convert input signal and filter i... DFT-based Filtering: does it matter if I normalize by N in the FFT or iFFT?

Re: Hanning Windowing

palm...@hotmail.com - Dec 7 2007
I supose that you're going to do a FFT, isn't it? You have to buffer N samples of your signal and multiply each sample by a N samples of a Hanning window: W(n)=0.5*(1-cos(2*pi... Re: Hanning Windowing

Re: Block Floating point FFT or 32 bits precision FFT

Andrew V. Nesterov - Dec 6 2001
> Date: Wed, 5 Dec 2001 11:47:49 +0100 > From: "Curl" > Subject: Block Floating point FFT or 32 bits precision FFT ? > > Sorry, this is my second question in tw... Re: Block Floating point FFT or 32 bits precision FFT

fractional-octave band filters via FFT

normanrg - Feb 26 2004
Does anyone out there have experience or info in how to construct fractional-octave bandwidth filters using FFTs? It does not seem to be an accepted method, yet I cannot under... fractional-octave band filters via FFT

MMX/SSE Optimized FFT (fht based) source code is required

usmanarif_pk - Aug 12 2005
HI every one! Can any one kindly tell me about the optimized version of the source code (in C) for FFT algorithm (fht based, especially the code by R. Mayer)? Is there any ver... MMX/SSE Optimized FFT (fht based) source code is required

circular convolution again   [5 Articles]

Sameer Kibey - Nov 18 2002
Hello! I have some more comments... Akash's points on the comparison between FFT and convolution are indeed agreeable. But I guess the original query by John was abt the use of... circular convolution again

Filter to remove noise from a corrupted song   [3 Articles]

Farah Rasheed - Nov 18 2007
Hi everyone, I have a question about filtering a noise signal in MATLAB. I have a corrupted sound file and I loaded it in MATLAB and plotted the FFT of the signal. From the FF... Filter to remove noise from a corrupted song

Re: Block Floating point FFT or 32 bits precision FFT

Suciu Radu - Dec 11 2001
Since we are on this topic, I think that there is a serious dillema, while practically realising an FFT core: fixed point vs. floating point. I have stated some pro's and con'... Re: Block Floating point FFT or 32 bits precision FFT

Lowpass filter in C   [6 Articles]

dizige - Mar 20 2007
Hi, I'm new to DSP and just wrote a bunch of functions in C to process some audio data. I implemented a lowpass filter by convolving a 256-sample audio sequence with a sin... Lowpass filter in C

How to impoverish the FFT of a sound and keep the same sampling rate at once ?   [5 Articles]

arnaud_trolle - Oct 2 2006
Hi everyone ! I'm a beginner in audio DSP applications. I'm a student working in the field of sound quality. In this framework, I'm facing the following issue : I'd like to ... How to impoverish the FFT of a sound and keep the same sampling rate at once ?

??,?: a MPEG2 question   [2 Articles]

ZiP HE - Nov 29 2000
Hi, rsv, Thank you for your kind reply. can you tell me where I can find the hanning window equation? ISO11172-3 didnot offer it. regards ZiP -----????----- ???: Prasad... ??,?: a MPEG2 question

vocoder help

Pankaj Daga - Mar 20 2003
Hello everyone, I am new to DSP and have been going through Perry Cook's "Real Sound Synthesis" book. I have been trying to extend the vocoder example in the book. Basically, i... vocoder help

STFT time shift

ooon...@yahoo.se - May 6 2005
Dear all I'd like to know why it could be desirable to shift the time origin to the center of every segment (using "fftshift" on the segment in MATLAB) before doing the FFT in... STFT time shift

Finding LTAS

Amit Das - Aug 8 2005
Hi, I am trying to find the LTAS(Long term average rms spectrum) for a SET (about 50) of speech wavfiles rms equalized to 0.05 and sampled at 16k. I wanted to know the differenc... Finding LTAS

Cheap DSP for audio   [4 Articles]

Edson Brusque \Listas\ - Jun 29 2002
Hello, I'm trying to do fundamental frequency detection with analog (filters and PLLs) and a microprocessor (PIC) but the results are very bad. So I'm thinking about h... Cheap DSP for audio

RE: How to impoverish the FFT of a sound and keep the same sampling rate at once ?

radh...@wipro.com - Oct 8 2006
Bernhard, Even I am curious to know if there are any such ADC.I do agree with Jeff the need for the external filter. Thanks, radha meka ________________________________ ... RE: How to impoverish the FFT of a sound and keep the same sampling rate at once ?

Re: cd noise floor

Sigmund Gudvangen - Mar 31 2003
You get roughly 6 dB per bit, so 24 bits should give 20log10(2^24) = 145 dB, 16 bits gives 96 dB, etc. If you are using a FFT spectrum analyser the noise per frequency bin wi... Re: cd noise floor

Re: zeroing the FFT ( never ending story ? )

Michael Strothjohann - Oct 25 2001
Bob Cain schrieb: > > Michael Strothjohann wrote: > > > > Toni, > > > > First: Zero-padding isnt realy increasing the resolution of your > > spectra. I'm very,very sorry abou... Re: zeroing the FFT ( never ending story ? )

rough spectrum monitoring- faster than FFTW   [3 Articles]

stud...@inbox.lv - Jan 8 2008
Hello, is there any way to get near-realtime audio spectrum info faster than FFT ? For example- VST graphic 7 band EQ,with level meters for each band.. ... rough spectrum monitoring- faster than FFTW
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