I'm trying to integrate the FFTW3 (a GNU FFT library written in C, http://www.fftw.org/) into an iPhone app. I downloaded the source code and I found there are hundreds of .h and .c files along with a lot of other files I can't recognize. I'm not a linux expert so I don't really understand how the .configure file and other similar files ...
I'm using a DSP to control a sensorless brushless DC motor, The DSP is on a board which has a parallel port and a jtag connection (it's an eZdspTMS320F2812). What would be the best way to communicate between a PC application and the DSP as it was running? Ideally I'd like to have a GUI program with buttons like start, stop, accelerate, d...
Given a very simple ruby script: child = fork do system 'sleep 10000' end 5.times do sleep 1 puts "send kill to #{child}" Process.kill("QUIT", child) end QUIT signal is just lost. Where does it go? Something with default handler which just ignores it? How to send signal to all processes created by that fork? Is it possible t...
How do you invert an image (reversing grayscale) in MATLAB? ...
I'm implementing a 'filter sweep' effect (I don't know if it's called like that). What I do is basically create a low-pass filter and make it 'move' along a certain frequency range. To calculate the filter cut-off frequency at a given moment I use a user-provided linear function, which yields values between 0 and 1. My first attempt wa...
Is it useful to study the H.261 specification for an introduction into modern video compression technology, or should I start somewhere else? I'm not sure where to start, but H.261 seems simple enough to make it easy to grasp the concepts. ...
Hello, as the world cup is the main sport event and the Vuvuzelas are the most annoying sound in the world, I had an idea to remove them definitively by reading this new ( http://www.popsci.com/diy/article/2010-06/simple-software-can-filter-out-vuvuzela-whine) that told us that the sound has some frequencies at 233Hz + 466,932,1864Hz. ...
Is there a nice (pure Java) open source libary to get the frequence spectrum of samples taken from a AudioInputStream? ...
Implementing a low pass FIR filter, when should one use FFT and IFFT instead of time-domain convolution? The goal is to achieve the lowest CPU time required for real-time calculations. As I know, FFT has about O(n log n) complexity, but convolution in the time domain is of O(n²) complexity. To implement a low pass filter in the frequen...
Newbie ARM assembler question. I am writing my first arm assembler program and I am trying to code this C fragment. int x = somevalue1 << 12; // s19.12 int y = somevalue2 << 12; // s19.12 int a = somevalue3 << 12; // s19.12 int b = somevalue4 << 12; // s19.12 int c = somevalue4 << 12; // s19.12 long long acc = (long long) a * b;...
I've been playing around with Apple's aurioTouch demo which is sample code for their Audio Unit tutorial. This application allows simultaneous input/output from the mic. to speaker. It also renders a stereograph of the inputted sound from the mic. At a really high-level of this low-level process, the sample code defines an AudioCompone...
I am mostly a business programmer and I've not done anything in audio programming since the ZX Spectrum so I'm not sure how to even ask this question correctly. I just need some pointers in the right direction with regards to writing (Android in this case, but it is really a general question) applications which deal with audio such as a...
Given is an array of 320 elements (int16), which represent an audio signal (16-bit LPCM) of 20 ms duration. I am looking for a most simple and very fast method which should decide whether this array contains active audio (like speech or music), but not noise or silence. I don't need a very high quality of the decision, but it must be v...
Hi, all -- I've got code to calculate IIR filter coefficients, but they seem to lead to a really strange output. This is what the data looks like: sampled at 1 KHz with a 7 Hz excitation oscillation on top of it. I'd like to make the filter so that it filters with a cutoff frequency of 1 Hz. Based on what I have read on the web, t...
I am building an Iphone App and one of the tasks I need to accomplish is to provide the user the ability to add some sound effects including Echo effect, background music on the sounds being recorded through the app. Here is a similar type of App, Although this one maniuplate the sound files in Real Time. I don't really need to do this...
I can't find any understandable information on this topic. On the dutch wikipedia, I found that you can apply a z-transform which produces a formula in this form: www.music.mcgill.ca/~gary/618/week1/img15.gif This FIR filter is used as an example: upload.wikimedia.org/math/b/9/e/b9e2ed5184f98621922f716e5216f33d.png With the z-transform...
I recorded a radio signal into a .wav, I can open it in audacity and see that there is binary data encoded using a certain algorithm. Does anyone know of a way to process the signal that is contained within the .wav? so that i can extract the binary data from it? I know that I need to know the encoding algorithm for it to work properly,...
I am writing some signal processing software, and I am starting off by writing out a discrete convolution function. This works fine for the first ten thousand or so list of values, but as they get larger (say, 100k), I begin to get StackOverflow errors, of course. Unfortunately, I am having a lot of trouble converting the imperitive ...
I will work with a set of arbitrary images. Some of them might need some color correction. I've opened up an image that needed correction in Photoshop and noticed the yellows were a bit high in the Histogram. I applied Auto Color and that improved the image. How does that work ? How implement that ? Do I look for peaks in the histogra...
Well, I will try best not to make it as a 'I just want the code' question... I'm recently working on a project which requires some audio signal processing from local music files (e.g. iTunes Library). The whole work includes: Get the PCM data of an audio file (normally from iTunes library); <--AudioQueue (?) Write the PCM data to a ...