1/* 2 * Copyright (c) 2012 The WebRTC project authors. All Rights Reserved. 3 * 4 * Use of this source code is governed by a BSD-style license 5 * that can be found in the LICENSE file in the root of the source 6 * tree. An additional intellectual property rights grant can be found 7 * in the file PATENTS. All contributing project authors may 8 * be found in the AUTHORS file in the root of the source tree. 9 */ 10 11#include "webrtc/common_audio/signal_processing/include/real_fft.h" 12#include "webrtc/common_audio/signal_processing/include/signal_processing_library.h" 13#include "webrtc/test/testsupport/gtest_disable.h" 14#include "webrtc/typedefs.h" 15 16#include "testing/gtest/include/gtest/gtest.h" 17 18namespace webrtc { 19namespace { 20 21// FFT order. 22const int kOrder = 5; 23// Lengths for real FFT's time and frequency bufffers. 24// For N-point FFT, the length requirements from API are N and N+2 respectively. 25const int kTimeDataLength = 1 << kOrder; 26const int kFreqDataLength = (1 << kOrder) + 2; 27// For complex FFT's time and freq buffer. The implementation requires 28// 2*N 16-bit words. 29const int kComplexFftDataLength = 2 << kOrder; 30// Reference data for time signal. 31const int16_t kRefData[kTimeDataLength] = { 32 11739, 6848, -8688, 31980, -30295, 25242, 27085, 19410, 33 -26299, 15607, -10791, 11778, -23819, 14498, -25772, 10076, 34 1173, 6848, -8688, 31980, -30295, 2522, 27085, 19410, 35 -2629, 5607, -3, 1178, -23819, 1498, -25772, 10076 36}; 37 38class RealFFTTest : public ::testing::Test { 39 protected: 40 RealFFTTest() { 41 WebRtcSpl_Init(); 42 } 43}; 44 45TEST_F(RealFFTTest, CreateFailsOnBadInput) { 46 RealFFT* fft = WebRtcSpl_CreateRealFFT(11); 47 EXPECT_TRUE(fft == NULL); 48 fft = WebRtcSpl_CreateRealFFT(-1); 49 EXPECT_TRUE(fft == NULL); 50} 51 52TEST_F(RealFFTTest, RealAndComplexMatch) { 53 int i = 0; 54 int j = 0; 55 int16_t real_fft_time[kTimeDataLength] = {0}; 56 int16_t real_fft_freq[kFreqDataLength] = {0}; 57 // One common buffer for complex FFT's time and frequency data. 58 int16_t complex_fft_buff[kComplexFftDataLength] = {0}; 59 60 // Prepare the inputs to forward FFT's. 61 memcpy(real_fft_time, kRefData, sizeof(kRefData)); 62 for (i = 0, j = 0; i < kTimeDataLength; i += 1, j += 2) { 63 complex_fft_buff[j] = kRefData[i]; 64 complex_fft_buff[j + 1] = 0; // Insert zero's to imaginary parts. 65 }; 66 67 // Create and run real forward FFT. 68 RealFFT* fft = WebRtcSpl_CreateRealFFT(kOrder); 69 EXPECT_TRUE(fft != NULL); 70 EXPECT_EQ(0, WebRtcSpl_RealForwardFFT(fft, real_fft_time, real_fft_freq)); 71 72 // Run complex forward FFT. 73 WebRtcSpl_ComplexBitReverse(complex_fft_buff, kOrder); 74 EXPECT_EQ(0, WebRtcSpl_ComplexFFT(complex_fft_buff, kOrder, 1)); 75 76 // Verify the results between complex and real forward FFT. 77 for (i = 0; i < kFreqDataLength; i++) { 78 EXPECT_EQ(real_fft_freq[i], complex_fft_buff[i]); 79 } 80 81 // Prepare the inputs to inverse real FFT. 82 // We use whatever data in complex_fft_buff[] since we don't care 83 // about data contents. Only kFreqDataLength 16-bit words are copied 84 // from complex_fft_buff to real_fft_freq since remaining words (2nd half) 85 // are conjugate-symmetric to the first half in theory. 86 memcpy(real_fft_freq, complex_fft_buff, sizeof(real_fft_freq)); 87 88 // Run real inverse FFT. 89 int real_scale = WebRtcSpl_RealInverseFFT(fft, real_fft_freq, real_fft_time); 90 EXPECT_GE(real_scale, 0); 91 92 // Run complex inverse FFT. 93 WebRtcSpl_ComplexBitReverse(complex_fft_buff, kOrder); 94 int complex_scale = WebRtcSpl_ComplexIFFT(complex_fft_buff, kOrder, 1); 95 96 // Verify the results between complex and real inverse FFT. 97 // They are not bit-exact, since complex IFFT doesn't produce 98 // exactly conjugate-symmetric data (between first and second half). 99 EXPECT_EQ(real_scale, complex_scale); 100 for (i = 0, j = 0; i < kTimeDataLength; i += 1, j += 2) { 101 EXPECT_LE(abs(real_fft_time[i] - complex_fft_buff[j]), 1); 102 } 103 104 WebRtcSpl_FreeRealFFT(fft); 105} 106 107} // namespace 108} // namespace webrtc 109