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Questions tagged [vdsp]

vDSP is the (vector) digital signal processing portion of Apple’s Accelerate framework.

vDSP is the (vector) digital signal processing portion of Apple’s Accelerate framework, part of OS X and iOS. It provides a variety of vector and array functions for signal processing and other applications. vDSP uses hardware features such as SIMD (Single Instruction Multiple Data) to provide high performance.

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Cepstral Analysis for pitch detection

I'm looking to extract pitches from a sound signal. Someone on IRC just explained to me how taking a double FFT achieves this. Specifically: take FFT take log of square of absolute value (can be done with lookup table) take another FFT take…
P i
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Using IOS Accelerate Framework for 2D Signal Processing on Non-Power-of-Two images?

//EDIT... I'm editing my question slightly to address the issue of working specifically with non-power-of-two images. I've got a basic structure that works with square grayscale images with sizes like 256x256 or 1024x1024, but can't see how to…
Angus Forbes
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How to smooth interpolation of a float array into a bigger array?

I'm stuck with interpolation in Swift. Can anyone help me with that? I want to interpolate the float array (say [0, 0, 100, 25, 0, 0, 0, 25, 0, 0, 0]) into another array with some given size (for example 128). I found an article (Use Linear…
aibek
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iOS FFT Draw spectrum

I've read these question: Using the Apple FFT and Accelerate Framework How do I set up a buffer when doing an FFT using the Accelerate framework? iOS FFT Accerelate.framework draw spectrum during playback They all describe how to setup fft with the…
user2173177
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iPhone Image Processing with Accelerate Framework and vDSP

UPDATE: Please see additional question below with more code; I am trying to code a category for blurring an image. My starting point is Jeff LaMarche's sample here. Whilst this (after the fixes suggested by others) works fine, it is an order of…
Roger
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Fast Fourier transforms on GPU on iOS

I am implementing compute intensive applications for iOS (i.e., iPhone or iPad) that heavily use fast Fourier transforms (and some signal processing operations such as interpolations and resampling). What are the best libraries and API that allows…
JustDoIt
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Is it possible to store the result in one of the input vectors in the vDSP framework

In the vDSP functions of the Accelerate Framework, all the functions require you to input a result vector. Is it correct to pass the input vector (or one of the input vectors) as the result vector if I no longer need whatever was in the original…
user1357607
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vDSP_ztoc producing odd results

I'm trying to figure out the vDSP functions and the results I'm getting are very strange. This is related to this question: Using std::complex with iPhone's vDSP functions Basically I am trying to make sense of vDSP_vdist as I start off with a…
Goz
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Swift vDSP rFFT not same as Python np.fft.rfft()

I am trying to implement real FFT in iOS, for that i am using Accelerate Framework. Here is my Code for Swift. class FFT { private var fftSetup: FFTSetup? private var log2n: Float? private var length: Int? func initialize(count: Int){ length =…
Muhammad Faizan
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Efficiently generate a Sine wave in IOS

What is the most efficient way of generating a sine wave for a device running IOS. For the purposes of the exercise assume a frequency of 440Hz and a sampling rate of 44100Hz and 1024 samples. A vanilla C implementation looks something like. #define…
TJA
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problems calculating frequency response out of sine sweeps

I'm currently trying to calculate the frequency response of the iphone's speaker/microphone roundtrip. I play a sine sweep on the speaker, record it via the microphone and try to get the frequency response out of that. final goal is to be able to…
Maximilian Körner
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Accelerate's vImage vs. vDSP

I'm trying to use the Accelerate framework on iOS to bypass the fact that Core Image on iOS doesn't support custom filters/kernels. I'm developing an edge detection filter using two convolutions with a Sobel kernel, but starting with a simple…
mgaldieri
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Is there a function to calculate linear regression for array of points in Accelerate Framework for iPhone?

I am looking for a fastest / easiest solution to calculate regression for bunch of double points stored in array. I have tried to find proper function in Accelerate framework or tutorial but with no luck. Has anyone done it?
Lukasz
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How to use apple's Accelerate framework in swift in order to compute the FFT of a real signal?

How am I supposed to use the Accelerate framework to compute the FFT of a real signal in Swift on iOS? Available example on the web Apple’s Accelerate framework seems to provide functions to compute the FFT of a signal efficiently. Unfortunately,…
Jeremy Cochoy
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Why does the documentation say to use the vDSP_DFT instead of FFT

On apple documentation, it says We suggest you use the DFT routines instead of these. or Use the DFT routines instead of these wherever possible. (For example, instead of calling vDSP_fft_zip with a setup created with vDSP_create_fftsetup, call…
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