fft understanding
Can somebody give a good explanation of FFT image transform How the FFT transformed image and it's Re^2+Im^2 image can be analyzed? I just want to understand something when loiking to the image and it's frequency. ...
signal-processing
What's the fastest way to approximate the period of data using Octave?
I have a set of data that is periodic (but not sinusoidal). I have a set of time values in one vector and a set of amplitudes in a second vector. I'd like to quickly approximate the period of the function. Any suggestions? Specifically, here's my current code. I'd like to approximate the period of the vector x(:,2) against the vector t....
Smoothing Small Data Set With Second Order Quadratic Curve
I'm doing some specific signal analysis, and I am in need of a method that would smooth out a given bell-shaped distribution curve. A running average approach isn't producing the results I desire. I want to keep the min/max, and general shape of my fitted curve intact, but resolve the inconsistencies in sampling. In short: if given a se...
Matlab: Analysis of signal
Hi, I have a problem with this task: For free route perform frequency analysis and give parametrs of each signal component: time of beginning and ending of each component beginning and ending frequency amplitude (in time domain) in the beginning and end of each signal's component level of noise in dB Assume, that, the parametrs of e...
TV audio processing with TV capture card
Hello, I'm looking for an open source library or framework to process audio signal from a TV capture card. The idea is to detect TV ad spots and register the time and the channel where them happends. I never worked in something like this, so, any information, link, idea is welcome. Thanks in advance! EDIT: I don't care about the langu...
Saturated addition of two signed Java 'long' values
How can one add two long values in Java so that if the result overflows then it is clamped to the range Long.MIN_VALUE..Long.MAX_VALUE? For adding ints one can perform the arithmetic in long precision and cast the result back to an int, e.g.: int saturatedAdd(int x, int y) { long sum = (long) x + (long) y; long clampedSum = Math.ma...
Daubechies-4 Transform in MATLAB
Hello: I have a 4x4 matrix which I wish to decompose into 4 frequency bands (LL, HL, LH, HH where L=low, H=high) by using a one-level Daubechies-4 wavelet transform. As a result of the transform, each band should contain 2x2 coefficients. How can I do this in MATLAB? I know that MATLAB has dbaux and dbwavf functions. However, I'm not su...
Creating a music catalog and extracting first 30 seconds as soon as the first words are sung
I already read a question: Separation of singing voice from music. I don’t need this complex audio processing. I only need some detection mechanism that would detect that there is some voice/vocal playing while the music is playing (or not playing) I need to extract first 30 seconds when a vocalist starts singing along with full band m...
What should I do as a DSP programming beginner ?
I'd like to learn TI DSP programming. I am a beginner. I have the processors : TMS320VC5505 and TMX320VC5505DZCH What hardware should I have ? and How can I program the DSP ? (c or assembly) Thank you ...
Generating a scalogram of a signal
Hi there, I'm trying to build a scalogram view for my app to see whether there is relevant information we can retrieve from a wavelet transform as opposed to using a spectograms to see what can be retrieved via an FFT. So far I can take a wave form and I can perform the forward wavelet transform on it. However I am lost at the next st...
Convolving two signals
Calculate the convolution of the following signals (your answer will be in the form of an equation): h[n] = [n-1] + [n+1], x[n] = [n-a] + [n+b] I'm lost as to what I do with h and x. Do I simply multiply them? h[n]*x[n]? I programmed convolution with several types of blurs and edge detectors, but I don't see how to translate that...
Reducing moire when downsampling halftone comic images.
How can I reduce moire effects when downsampling halftone comic book images during live zoom on an iPhone or iPad? I am writing a comic book viewer. It would be nice to provide higher resolution images and allow the user to zoom in while reading the comic book. However, my client is averse to moire effects and will not allow this feat...
Change the playback rate of a track in real time on Android
Hello, I would like to know if somebody knows a library to changing the playback rate of a track in real time. My idea is to load a track and change its playback rate to half or double. Firstly, I tried with MusicPlayer but is was not possible at all and then I tried with SoundPool. The problem is that with SoundPool I can´t change the ...
TMS320C64x Quick start reference for programmers
Hello Is thare any quickstart guide for programmers for writing DSP-accelerated appliations for TMS320C64x? I have a program with custom algorythm (not the fft, or usial filtering) and I want to accelerate it using multi-DSP coprocessor. So, how should I modify source to move computation from main CPU to DSPs? What limitations are ther...
i2s0: transmitter underrun (0)
were doing some audio stuff and I keep seeing this in the Organizer > Console. Sun May 2 20:16:48 unknown kernel[0] : i2s0: transmitter underrun (0) Are these transmitter underruns bad? I think its just when were shutting down audio input...but could a few of these cause some issues later on? ...
What exactly is a "Sample"?
From the OpenAL documentation it looks like if an Sample is one single floating point value like lets say 1.94422 Is that correct? Or is a sample an array of a lot of values? What are audio programming dudes talking about when they say "Sample"? Is it the smallest possible snippet of an audio file? I imagine an uncompressed audio file ...
Using imtophat in Matlab
I'm trying to do top hat filtering in matlab. The imtophat function looks promising, but I have no idea how to use it. I dont have a lot of work with Matlab before. I am trying to look find basically small spots several pixels wide that are local max in my 2 dimensional array. ...
Generating data on unlevel background
I want to make an unlevel background and then generate some test data on that using Matlab. I was not clear when I asked this question earlier. So for this simple example for i = 1:10 for j = 1:10 f(i,j)=X.^2 + Y.^2 end end where X and Y have been already defined, it plots it on a flat surface. I don't want to distort the fu...
Recognizing individual voices
I plan to write a conversation analysis software, which will recognize the individual speakers, their pitch and intensity. Pitch and intensity are somewhat straightforward (pitch via autocorrelation). How would I go about recognizing individual speakers, so I can record his/her features? Will storing some heuristics for each speaker's ...
Using Cepstrum for PDA
Hey, I am currently deleveloping a algorithm to decide wheather or not a frame is voiced or unvoiced. I am trying to use the Cepstrum to discriminate between these two situations. I use MATLAB for my implementation. I have some problems, saying something generally about the frame, but my currently implementation looks like (I'm award of...