2014/10/15 下午 10:12:24

iphone Programming Glossary: outputbuffer

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

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 to split vector vDSP_ztoc.. fft vDSP_fft_zrip fftSetup A stride log2n FFT_FORWARD convert split real form to split vector vDSP_ztoc A 1 COMPLEX outputBuffer 2 nOver2 Demetri then goes on to determine the 'dominant' frequency as follows float dominantFrequency 0 int bin 1 for int.. 'dominant' frequency as follows float dominantFrequency 0 int bin 1 for int i 0 i n i 2 float curFreq MagnitudeSquared outputBuffer i outputBuffer i 1 if curFreq dominantFrequency dominantFrequency curFreq bin i 1 2 memset outputBuffer 0 n sizeof SInt16..