1 /* 2 * Copyright (C) 2010 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); you may not 5 * use this file except in compliance with the License. You may obtain a copy of 6 * the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT 12 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the 13 * License for the specific language governing permissions and limitations under 14 * the License. 15 */ 16 17 #ifndef LEGACY_TALKIN_FFT_H 18 #define LEGACY_TALKIN_FFT_H 19 20 class Fft { 21 public: 22 Fft(void); 23 24 virtual ~Fft(void); 25 26 // Prepare for radix-2 FFT's of size (1<<pow2) 27 void fftInit(int pow2); 28 29 // Forward fft. Real time-domain components in x, imaginary in y 30 void fft(float *x, float *y); 31 32 // Inverse fft. Real frequency-domain components in x, imaginary in y 33 void ifft(float *x, float *y); 34 35 // Compute the dB-scaled log-magnitude spectrum from the real spectal 36 // amplitude values in 'x', and imaginary values in 'y'. Return the 37 // magnitude spectrum in z. Compute 'n' components. 38 int fftLogMag(float *x, float *y, float *z, int n); 39 40 int fftGetSize(); 41 42 int fftGetPower2(); 43 44 // Return the power of 2 required to contain at least size samples. 45 static int fftPow2FromWindowSize(int size) { 46 int pow2 = 1; 47 while ((1 << pow2) < size) 48 pow2++; 49 return pow2; 50 } 51 52 private: 53 // Free up memory and reset the static globals. 54 void fftCleanup(); 55 56 // Create the sine/cosine basis tables and return the size of the FFT 57 // corresponding to pow2. 58 int fftMakeTable(int pow2); 59 60 float* mSine; 61 float* mCosine; 62 int mFftTableSize; 63 int mFftSize; 64 int mPower2; 65 int mBase; 66 }; 67 68 #endif // LEGACY_TALKIN_FFT_H 69
