139 lines
4.2 KiB
C
139 lines
4.2 KiB
C
/*
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DeaDBeeF -- the music player
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Copyright (C) 2009-2021 Alexey Yakovenko and other contributors
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This software is provided 'as-is', without any express or implied
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warranty. In no event will the authors be held liable for any damages
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arising from the use of this software.
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Permission is granted to anyone to use this software for any purpose,
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including commercial applications, and to alter it and redistribute it
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freely, subject to the following restrictions:
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1. The origin of this software must not be misrepresented; you must not
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claim that you wrote the original software. If you use this software
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in a product, an acknowledgment in the product documentation would be
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appreciated but is not required.
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2. Altered source versions must be plainly marked as such, and must not be
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misrepresented as being the original software.
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3. This notice may not be removed or altered from any source distribution.
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*/
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#include "fft.h"
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#include <Accelerate/Accelerate.h>
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// Some newer spectrum calculation methodology, adapted but not copied wholesale
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// Mostly about a dozen or two lines of Cocoa and vDSP code
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// AudioSpectrum: A sample app using Audio Unit and vDSP
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// By Keijiro Takahashi, 2013, 2014
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// https://github.com/keijiro/AudioSpectrum
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struct SpectrumData
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{
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unsigned long length;
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Float32 data[0];
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};
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static int _fft_size = 0;
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static vDSP_DFT_Setup _dftSetup = NULL;
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static DSPSplitComplex _dftBuffer = {0};
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static Float32 *_window = NULL;
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static struct SpectrumData *_rawSpectrum = NULL;
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// Apparently _mm_malloc is Intel-only on newer macOS targets, so use supported posix_memalign
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// malloc() is allegedly aligned on macOS, but I don't know for sure
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static void *_memalign_calloc(size_t count, size_t size, size_t align) {
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size *= count;
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void *ret = NULL;
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if(posix_memalign(&ret, align, size) != 0) {
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return NULL;
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}
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bzero(ret, size);
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return ret;
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}
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static void
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_init_buffers(int fft_size) {
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if(fft_size != _fft_size) {
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fft_free();
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_fft_size = 0;
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_dftSetup = vDSP_DFT_zrop_CreateSetup(NULL, fft_size * 2, vDSP_DFT_FORWARD);
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if(!_dftSetup) return;
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_dftBuffer.realp = _memalign_calloc(fft_size, sizeof(Float32), 16);
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_dftBuffer.imagp = _memalign_calloc(fft_size, sizeof(Float32), 16);
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if(!_dftBuffer.realp || !_dftBuffer.imagp) return;
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_window = _memalign_calloc(fft_size * 2, sizeof(Float32), 16);
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if(!_window) return;
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vDSP_blkman_window(_window, fft_size * 2, 0);
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Float32 normFactor = 2.0f / (fft_size * 2);
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vDSP_vsmul(_window, 1, &normFactor, _window, 1, fft_size * 2);
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_rawSpectrum = (struct SpectrumData *) _memalign_calloc(sizeof(struct SpectrumData) + sizeof(Float32) * fft_size, 1, 16);
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if(!_rawSpectrum) return;
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_rawSpectrum->length = fft_size;
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_fft_size = fft_size;
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}
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}
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void fft_calculate(const float *data, float *freq, int fft_size) {
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if(!freq || !fft_size) return;
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_init_buffers(fft_size);
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if(!_fft_size || !data) {
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// Decibels
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float kZeroLevel = -128.0;
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vDSP_vfill(&kZeroLevel, freq, 1, fft_size);
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return;
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}
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// Split the waveform
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DSPSplitComplex dest = { _dftBuffer.realp, _dftBuffer.imagp };
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vDSP_ctoz((const DSPComplex*)data, 2, &dest, 1, fft_size);
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// Apply the window function
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vDSP_vmul(_dftBuffer.realp, 1, _window, 2, _dftBuffer.realp, 1, fft_size);
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vDSP_vmul(_dftBuffer.imagp, 1, _window + 1, 2, _dftBuffer.imagp, 1, fft_size);
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// DFT
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vDSP_DFT_Execute(_dftSetup, _dftBuffer.realp, _dftBuffer.imagp, _dftBuffer.realp, _dftBuffer.imagp);
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// Zero out the Nyquist value
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_dftBuffer.imagp[0] = 0.0;
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// Calculate power spectrum
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Float32 *rawSpectrum = _rawSpectrum->data;
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vDSP_zvmags(&_dftBuffer, 1, rawSpectrum, 1, fft_size);
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// Add -128dB offset to avoid log(0)
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float kZeroOffset = 1.5849e-13;
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vDSP_vsadd(rawSpectrum, 1, &kZeroOffset, rawSpectrum, 1, fft_size);
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// Convert power to decibel
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float kZeroDB = 0.70710678118f; // 1/sqrt(2)
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vDSP_vdbcon(rawSpectrum, 1, &kZeroDB, rawSpectrum, 1, fft_size, 0);
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cblas_scopy(fft_size, rawSpectrum, 1, freq, 1);
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}
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void __attribute__((destructor)) fft_free(void) {
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free(_dftBuffer.realp);
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free(_dftBuffer.imagp);
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free(_window);
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free(_rawSpectrum);
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if(_dftSetup != NULL) {
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vDSP_DFT_DestroySetup(_dftSetup);
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}
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_dftBuffer.realp = NULL;
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_dftBuffer.imagp = NULL;
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_window = NULL;
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_rawSpectrum = NULL;
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_dftSetup = NULL;
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}
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