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