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109 lines
3.8 KiB
C++
109 lines
3.8 KiB
C++
/*
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* Copyright (c) 2012 The WebRTC project authors. All Rights Reserved.
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*
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* Use of this source code is governed by a BSD-style license
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* that can be found in the LICENSE file in the root of the source
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* tree. An additional intellectual property rights grant can be found
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* in the file PATENTS. All contributing project authors may
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* be found in the AUTHORS file in the root of the source tree.
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*/
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#include "webrtc/common_audio/signal_processing/include/real_fft.h"
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#include "webrtc/common_audio/signal_processing/include/signal_processing_library.h"
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#include "webrtc/test/testsupport/gtest_disable.h"
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#include "webrtc/typedefs.h"
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#include "testing/gtest/include/gtest/gtest.h"
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namespace webrtc {
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namespace {
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// FFT order.
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const int kOrder = 5;
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// Lengths for real FFT's time and frequency bufffers.
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// For N-point FFT, the length requirements from API are N and N+2 respectively.
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const int kTimeDataLength = 1 << kOrder;
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const int kFreqDataLength = (1 << kOrder) + 2;
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// For complex FFT's time and freq buffer. The implementation requires
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// 2*N 16-bit words.
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const int kComplexFftDataLength = 2 << kOrder;
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// Reference data for time signal.
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const int16_t kRefData[kTimeDataLength] = {
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11739, 6848, -8688, 31980, -30295, 25242, 27085, 19410,
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-26299, 15607, -10791, 11778, -23819, 14498, -25772, 10076,
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1173, 6848, -8688, 31980, -30295, 2522, 27085, 19410,
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-2629, 5607, -3, 1178, -23819, 1498, -25772, 10076
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};
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class RealFFTTest : public ::testing::Test {
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protected:
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RealFFTTest() {
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WebRtcSpl_Init();
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}
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};
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TEST_F(RealFFTTest, CreateFailsOnBadInput) {
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RealFFT* fft = WebRtcSpl_CreateRealFFT(11);
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EXPECT_TRUE(fft == NULL);
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fft = WebRtcSpl_CreateRealFFT(-1);
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EXPECT_TRUE(fft == NULL);
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}
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TEST_F(RealFFTTest, RealAndComplexMatch) {
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int i = 0;
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int j = 0;
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int16_t real_fft_time[kTimeDataLength] = {0};
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int16_t real_fft_freq[kFreqDataLength] = {0};
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// One common buffer for complex FFT's time and frequency data.
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int16_t complex_fft_buff[kComplexFftDataLength] = {0};
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// Prepare the inputs to forward FFT's.
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memcpy(real_fft_time, kRefData, sizeof(kRefData));
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for (i = 0, j = 0; i < kTimeDataLength; i += 1, j += 2) {
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complex_fft_buff[j] = kRefData[i];
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complex_fft_buff[j + 1] = 0; // Insert zero's to imaginary parts.
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};
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// Create and run real forward FFT.
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RealFFT* fft = WebRtcSpl_CreateRealFFT(kOrder);
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EXPECT_TRUE(fft != NULL);
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EXPECT_EQ(0, WebRtcSpl_RealForwardFFT(fft, real_fft_time, real_fft_freq));
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// Run complex forward FFT.
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WebRtcSpl_ComplexBitReverse(complex_fft_buff, kOrder);
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EXPECT_EQ(0, WebRtcSpl_ComplexFFT(complex_fft_buff, kOrder, 1));
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// Verify the results between complex and real forward FFT.
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for (i = 0; i < kFreqDataLength; i++) {
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EXPECT_EQ(real_fft_freq[i], complex_fft_buff[i]);
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}
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// Prepare the inputs to inverse real FFT.
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// We use whatever data in complex_fft_buff[] since we don't care
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// about data contents. Only kFreqDataLength 16-bit words are copied
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// from complex_fft_buff to real_fft_freq since remaining words (2nd half)
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// are conjugate-symmetric to the first half in theory.
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memcpy(real_fft_freq, complex_fft_buff, sizeof(real_fft_freq));
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// Run real inverse FFT.
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int real_scale = WebRtcSpl_RealInverseFFT(fft, real_fft_freq, real_fft_time);
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EXPECT_GE(real_scale, 0);
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// Run complex inverse FFT.
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WebRtcSpl_ComplexBitReverse(complex_fft_buff, kOrder);
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int complex_scale = WebRtcSpl_ComplexIFFT(complex_fft_buff, kOrder, 1);
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// Verify the results between complex and real inverse FFT.
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// They are not bit-exact, since complex IFFT doesn't produce
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// exactly conjugate-symmetric data (between first and second half).
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EXPECT_EQ(real_scale, complex_scale);
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for (i = 0, j = 0; i < kTimeDataLength; i += 1, j += 2) {
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EXPECT_LE(abs(real_fft_time[i] - complex_fft_buff[j]), 1);
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}
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WebRtcSpl_FreeRealFFT(fft);
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}
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} // namespace
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} // namespace webrtc
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