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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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Strange results being returned from vDSP_conv

I've been using the Accelerate framework to do some audio signal processing and I've been using the vDSP_conv function to perform some cross-correlations. Usually, the values returned look like this (left column is the array index, and right column…
user3489828
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Speed up summing components in a vector

I would like to create an array from another array by summing the components in blocks of four, e.g.: float inVector[256]; float outVector[64]; for(int i=0; i<64; i++){ for(int j=0; j<4; j++){ int k = 4*i + j; outVector[i] +=…
Sten
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iOS: using vDSP functions in 64bit

In iOS, I have a function call that depends on vDSP_vgathr, a member of Apple's Accelerate framework: int pix = image.size.height * image.size.width; float * array = (float *)malloc(sizeof(float) * pix * 4); float * colorPlane = (float…
Scott
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Overlap add in audio analysis-synthesis

I wrote some code that takes an audio signal (currently a sine wave) as an input and does the following: Take frames of n (1024) samples Apply FFT Apply iFFT Play output With this process the output signal is basically the same as the input…
Merlevede
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Overlap add for signal synthesis

I apologize if this question is very basic. I'm transforming an audio signal (currently a plain sine wave) from the time-domain to the frequency-domain using FFT, and then back to the time-domain to compare the difference to the original…
Merlevede
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What's up with vDSP?

In trying to use functions like zrvmul, vvsinf, and vvcosf (defined in vForce.h) I get "no matching function" errors. I am #including the accelerate framework, and have it linked in build phases. Moreover, I'm using other accelerate functions like…
John Seales
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Perform FFT in Objective-C of MATLAB File

For a current project I'm working on, I need to test the FFT I've implemented in Objective-C using the Accelerate Framework on a sin wave generated in MATLAB before I modify the FFT to read in real-time data. However, I'm a bit lost on how to load…
narner
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Is there a vDSP function to do the following operation?

Sorry if this is obvious. I'm just getting into the Accelerate framework and trying to go beyond the very simple stuff. I'm staring down the vDSP reference but I'm not sure how the following would be phrased or what it might be called in technical…
Luke
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ListCorrelate vDSP equivalent for convolution of {{a,b,c},{d,e,f}} and {{g,h,i},{j,k,i},{l,m,n}}

If I ListCorrelate two list of real doubles {{a,b,c},{d,e,f}} {{g,h,i},{j,k,l},{m,n,o}} in Mathematica I get {{a*g + b*h + c*i + d*j + e*k + f*l},{a*j + b*k + c*l + d*m + e*n + f*o}} Can anyone tell me the equivalent function in Apple's vDSP for…
ddd
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How to use vDSP in iOS for converting sound file to FFT

I am new to Audio framework but after searching a while i found Accelerate framework provided by iOS api for Digital Signal Processing. In my project i want to convert a sound file to fft so that i can compare two sounds using fft. So how should i…
Prerna chavan
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problems with apples vDSP examples

I'm having problems with apples examples for vDSP. I tried all of them but i need the convolution sample in the end. I can't even get it through the linker: Undefined symbols for architecture i386: "_conv", referenced from: _ConvTiming in…
Maximilian Körner
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Performing buffering/windowing with overlap add CMSampleBufferRef

I'm trying to perform some basic DSP functions on PCM audio data which I retrieve from a video file using AVAssetReader on the iPhone. I'm reading the buffers correctly, number of samples per buffer is 8192 (is that by default? can that be…
Ariel Krieger
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Perform real time FFT from Apple Watch microphone

I'm developing an app that would be listening waiting for a certain frequency to be detected by the microphone. As far as I researched, I think the best way to do this is by performing a Fast Fourier Transform to the real time audio signal (if…
kildos
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Perform basic arithmetic operations on AudioKit FM oscillator parameters: Interpolation & time Transition

Does AudioKit provide a method to calculate interpolated values of discrete array members? Does AudioKit provide a method to smooth transition operation between parameters of an oscillator like baseFrequency, AKOperation.periodicTrigger or…
jumbopilot
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Accelerate vDSP FFT resulting in NaN under demanding scenario

I'm using the vDSP framework for a real-time audio application based on FFT computation. After having lots of problems trying to figure out why the algorithm was producing incorrect results, I found out the following comment on the official vDSP…
Andres Perez-Lopez
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