2014/10/15 下午 10:15:44

iphone Programming Glossary: vdsp_ctoz

iPhone Accelerate Framework FFT vs Matlab FFT

http://stackoverflow.com/questions/10820488/iphone-accelerate-framework-fft-vs-matlab-fft

fft_data fft_data.realp double malloc 8 sizeof double fft_data.imagp double malloc 8 sizeof double vDSP_ctoz COMPLEX ffx 2 fft_data 1 nOver2 split data 1 16 into odds and evens vDSP_fft_zrip fftSetup fft_data 1 log2n kFFTDirection_Forward.. you're mixing single precision float and double precision double routines. Your data is double so you should be using vDSP_ctozD not vDSP_ctoz and vDSP_fft_zripD rather than vDSP_fft_zrip etc. Another thing to watch out for different FFT implementations.. single precision float and double precision double routines. Your data is double so you should be using vDSP_ctozD not vDSP_ctoz and vDSP_fft_zripD rather than vDSP_fft_zrip etc. Another thing to watch out for different FFT implementations use different..

Multiple Clipped Rects to Create Collage in Core Graphics

http://stackoverflow.com/questions/2234668/multiple-clipped-rects-to-create-collage-in-core-graphics

Using the apple FFT and accelerate Framework

http://stackoverflow.com/questions/3398753/using-the-apple-fft-and-accelerate-framework

masquerades n real #s as n 2 complex #s 2 1i 4 3i ... 2. splits to A.realP 2 4 ... n 2 elts A.compP 1 3 ... n 2 elts vDSP_ctoz COMPLEX originalReal 2 stride 2 as each complex # is 2 floats A 1 stride 1 in A.realP .compP nOver2 n 2 elts You would..

iPhone FFT with Accelerate framework vDSP

http://stackoverflow.com/questions/6358764/iphone-fft-with-accelerate-framework-vdsp

i 1 Look at the real signal as an interleaved complex vector by casting it. Then call the transformation function vDSP_ctoz to get a split complex vector which for a real signal divides into an even odd configuration. vDSP_ctoz COMPLEX originalReal.. function vDSP_ctoz to get a split complex vector which for a real signal divides into an even odd configuration. vDSP_ctoz COMPLEX originalReal 2 A 1 nOver2 Set up the required memory for the FFT routines and check its availability. setupReal..

FFT on iPhone to ignore background noise and find lower pitches

http://stackoverflow.com/questions/7181630/fft-on-iphone-to-ignore-background-noise-and-find-lower-pitches

... get the data AudioUnitRender ... convert int16 to float Convert ... divide the signal into even odd configuration vDSP_ctoz COMPLEX outputBuffer 2 A 1 nOver2 apply the fft vDSP_fft_zrip fftSetup A stride log2n FFT_FORWARD convert split real form.. which I then apply by inserting vDSP_vmul outputBuffer 1 window 1 transferBuffer 1 windowSize before the vDSP_ctoz function. I then change the rest of the code to use 'transferBuffer' instead of outputBuffer ... but so far haven't noticed..