I want to take audio PCM data and find peaks in it. Specifically, I want to return the frequency and time at which a peak occurs. My understanding of this is that I have to take the PCM data and dump it into an array, setting it as the real values with the complex parts set to 0. I then take the FFT, and I get an array back. If each ...
How would I go about using Python to read the frequency peaks from a WAV PCM file and then be able to generate an image of it, for spectogram analysis? I'm trying to make a program that allows you to read any audio file, converting it to WAV PCM, and then finding the peaks and frequency cutoffs. ...
Hello, I've got this code, but it keeps returning random frequencies from 0 to about 1050. Please can you help me understand why this is happening. My data length is 1024, sample rate is 8192, and data is a short array filled with input data from the mic. float *iSignal = new float[2048]; float *oSignal = new float[2048]; int pitch =...
Hello, I'm trying to do real time pitch detection of a users singing, but I'm running into alot of problems. I've tried lots of methods, including FFT (FFT Problem (Returns random results)) and autocorrelation (Autocorrelation pitch detection returns random results with mic input), but I can't seem to get any methods to give a good resu...
Hello, This is not a "programming" question. But I'm sure it's something that is widely known and understood in this community. I have an image, x, and a much smaller image, y, and I need to convolve the two by multiplying their FFTs. But since they are not the same size I don't know how to do the frequency domain multiplication. I ta...
I want to analyze MIC audio on an ongoing basis (not just a snipper or prerecorded sample), and display frequency graph and filter out certain aspects of the audio. Is the iPhone powerful enough for that? I suspect the answer is a yes, given the Google and iPhone voice recognition, Shazaam and other music recognition apps, and guitar t...
I'm trying to write a simple tuner (no, not to make yet another tuner app), and am looking at the AurioTouch sample source (has anyone tried to comment this code??). My worry is that aurioTouch doesn't seem to actually work very well when looking at the frequency domain graph. I play a single note on an instrument and I don't see a nic...
Hi. With limited resources such as slower CPUs, code size and RAM, how best to detect the pitch of a musical note, similar to what an electronic or software tuner would do? Should I use: Kiss FFT FFTW Discrete Wavelet Transform autocorrelation zero crossing analysis octave-spaced filters other? In a nutshell, what I am trying to d...
I'm interested in learning about, and writing a system that will extract features from audio files (mp3, wav, etc) which can later be used for whatever purpose. In the future I hope to use it to write some software for music similarity. Are there any libraries that exist to help? I know of libxtract, but haven't used it. Also, are ...
Hello, I'm trying to do real-time pitch detection using C++. I'm testing some code from performous (http://performous.org/), because everything else hasn't worked for me. I know for sure that this works, but i just cant get it to work. I've been trying this for a few weeks now, and i haven't been able to get any pitch detection code wor...
As a follow-up to my previous question, if I want my smartphone application to detect a certain musical note, and I only need to know whether the incoming sound is that musical note or not, with a certain amount of fuzziness, to allow the note to be off-key by x cents. Given that, is there a superior method over others for speed and acc...
My question has to do with the physical meaning of the results of doing the spectral analysis of a signal, or, put another way, of interpreting what comes out of throwing a signal into an FFT of a math package. Specifically: (i) take a signal, a time-varying voltage v(t) (ii) throw it into an FFT -- you get back a sequence of re...
Hi guys, So it looks like multicore and all its associated complications are here to stay. I am planning a software project that will definitely benefit from parallelism. The problem is that I have very little experience writing concurrent software. I studied it at University and understand the concepts and theory very well but have zer...
I have to apply a convolution filter on each row of many images. The classic is 360 images of 1024x1024 pixels. In my use case it is 720 images 560x600 pixels. The problem is that my code is much slower than what is advertised in articles. I have implemented the naive convolution, and it takes 2m 30s. I then switched to FFT using fft...
Could anybody please tell me whether I can perform this integration with FFT in MATLAB? How? Please answer as soon as possible with the details. Suppose there exists 2 rectangular planes, say, input accessed by x1 and y1 variables and the resulting plane is output accessed by tetax and tetay variables. This is the integral in pseudo-co...
Hi, I am trying to find a very fast and efficient Fourier transform (FFT). Does anyone know of any good ones. I need to run it on the iPhone so it must not be intensive. Instead, maybe you know of one that is wavelet like, i need frequency resolution but only a narrow band (vocal audio range up to 10khz max...even 10Khz might be too ...
I wanna make the Mel-Frequency Cepstrum Algorithm but there are some things that I don't understand. After FTT is done we need to "Map the powers of the spectrum obtained above onto the mel scale, using triangular overlapping windows." I know how to calculate the triangles and I also know how to pass to mel scale. I simply don't know w...
Hello, I receive input from the microphone and I apply the fft on it. After that, I put frequencies higher than 1KHz with zero (the high pass filter). I want to know how can I record the input from microphone after I passed it to fft and after the application of the high pass filter. I'm working with c#, what do I need to do? :P ...
Hello, is there a free c# library to do the fast fourier transform and its inverse? ...
I have an audio file and I am iterating through the file and taking 512 samples at each step and then passing them through an FFT. I have the data out as a block 514 floats long (Using IPP's ippsFFTFwd_RToCCS_32f_I) with real and imaginary components interleaved. My problem is what do I do with these complex numbers once i have them? ...