signal-processing

Extrapolation using fft in octave

Using GNU octave, I'm computing a fft over a piece of signal, then eliminating some frequencies, and finally reconstructing the signal. This give me a nice approximation of the signal ; but it doesn't give me a way to extrapolate the data. Suppose basically that I have plotted three periods and a half of f: x -> sin(x) + 0.5*sin(3*x) +...

Algorithm for voice comparison

Given two recorded voices in digital format, is there an algorithm to compare the two and return a coefficient of similarity? ...

Sound sample recognition library/code

I don't want sound-to-text software. What I need is the following: I'll record multiple (say 50+) audio streams (recordings of radio stations) from that recordings, I'll mark interesting audio clips - their length ranges from 2 to 60 seconds - there will be few thousands of such audio clips library should be able to find other instanc...

getting the value of a filter at an arbitrary time

Context: I'm trying to improve the values returned by the iPhone CLLocationManager, although this is a more generally applicable problem. The key is that CLLocationManger returns data on current velocity as and when it feels like it, rather than at a fixed sample rate. I'd like to use a feedback equation to improve accuracy v=(k*v)+(1-...

Generate quantization matrix

Hello, how can i generate quantizatinon metrices with diffrent size and quality, is there a function in matlab for this? ...

What is mean by Million cycles per second(MCPS)

hi , I have seen some performance figures are represented by MCPS unit, especially in some dsp codec performance. Can anybody clarify me this? /kanu__ ...

Simulink sim of rician channel ber process

Hi, I'm learning simulink and I want to use the rician channle block from the communications blockset. I'm told I need to change the format format. Would anyone have some sample code where they used the rician channels in simulink to model a bit error rate process? ...

DSP - Filtering frequencies using DFT

I'm trying to implement a DFT-based 8-band equalizer for the sole purpose of learning. To prove that my DFT implementation works I fed an audio signal, analyzed it and then resynthesized it again with no modifications made to the frequency spectrum. So far so good. I'm using the so-called 'standard way of calculating the DFT' which is b...

How to extract semi-precise frequencies from a WAV file using Fourier Transforms

Let us say that I have a WAV file. In this file, is a series of sine tones at precise 1 second intervals. I want to use the FFTW library to extract these tones in sequence. Is this particularly hard to do? How would I go about this? Also, what is the best way to write tones of this kind into a WAV file? I assume I would only need a simp...

OMAP 3530: How fast can I toggle an IO?

I am putting together an application for OMAP 3530 SoC. This application will run some user interface code on embedded linux and invoke waveform generation code on the DSP. The DSP and Linux sides will interact over DSP/BIOS link. My questions are: What is the highest frequency at which my DSP-side code can toggle a GPIO line? If I w...

Real-time spectrum analyzer with API

I'm looking for a C or C++ API that will give me real-time spectrum analysis of a waveform on Windows. I'm not entirely sure how large a sample window it should need to determine frequency content, but the smaller the better. For example, if it can work with a 0.5 second long sample and determine frequency content to the Hz, that would...

signal processing for a web programmer

What books would you recommend to a CS undergraduate that did mostly web programming all his life, in order to pick up signal processing ? I am looking for something at a grad level and more geared toward an average (or below average) programmer. ...

DSP - Filtering in the frequency domain via FFT

I've been playing around a little with the Exocortex implementation of the FFT, but I'm having some problems. Whenever I modify the amplitudes of the frequency bins before calling the iFFT the resulting signal contains some clicks and pops, especially when low frequencies are present in the signal (like drums or basses). However, this d...

FFT in MATLAB: wrong 0Hz frequency

Hello I want to use fft in MATLAB to analize some exprimental data saved as an excell file. my code: A=xlsread('Book.xls'); G=A'; x=G(2, : ); N=length(x); F=[-N/2:N/2-1]/N; X = abs(fft(x-mean(x),N)) X = fftshift(X); plot(F,X) But it plots a graph with a large 0Hz wrong component, my true frequency is about 395Hz and it is not shown i...

Scientific Data processing (Graph comparison and interpretation)

Hi stackoverflow friends, I'm trying to write a program to automate one of my more boring and repetitive work tasks. I have some programming experience but none with processing or interpreting large volumes of data so I am seeking your advice (both suggestions of techniques to try and also things to read to learn more about doing this s...

Determining the best audio quality.

How can you determine the best audio quality in a list of audio files of the same audio clip, with out looking at the audio file's header. The tricky part is that all of the files came from different formats and bit rates and they where all transcoded to the same format and bit rate. How can this be done efficiently? ...

TI-99 speech effect?

Hi, I want to make a program that takes recorded speech and transforms it so it sounds like it's coming from a Texas TI-99. Do you have any good ideas and resources for how to go about that? ...

Real-time equalizer for all audio on computer

Is it possible to capture all the sound from a computer and have it pass through a equalizer before reaching the speakers? How can you program a band pass filter on it? EDIT: I'm trying to get this on Windows (with Python? heh) but if there is a generic, cross-platform approach that would be great. ...

Does enlarging images make them easier to analyze programmatically?

Can you enlarge a feature so that rather than take up a certain number of pixels it actually takes up one or two times that many to make it easier to analyze? Would there be a way to generalize that in MATLAB? ...

Linux, C++ audio capturing (just microphone) library

I'm developing a musical game, it's like a singstar but instead of singing, you have to play the recorder. It's called oFlute, and it's still in early development stage. In the game, I capture the microphone input, then run a simple FFT analysis and compare the results to typical recorder's frequencies, thus getting the played note. A...