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/*
* Copyright (c) 2014 The WebRTC project authors. All Rights Reserved.
*
* Use of this source code is governed by a BSD-style license
* that can be found in the LICENSE file in the root of the source
* tree. An additional intellectual property rights grant can be found
* in the file PATENTS. All contributing project authors may
* be found in the AUTHORS file in the root of the source tree.
*/
#include "common_audio/fir_filter.h"
#include "common_audio/fir_filter_factory.h"
#include <string.h>
#include <memory>
#include "test/gtest.h"
namespace webrtc {
namespace {
static const float kCoefficients[] = {0.2f, 0.3f, 0.5f, 0.7f, 0.11f};
static const size_t kCoefficientsLength =
sizeof(kCoefficients) / sizeof(kCoefficients[0]);
static const float kInput[] = {1.f, 2.f, 3.f, 4.f, 5.f,
6.f, 7.f, 8.f, 9.f, 10.f};
static const size_t kInputLength = sizeof(kInput) / sizeof(kInput[0]);
void VerifyOutput(const float* expected_output,
const float* output,
size_t length) {
EXPECT_EQ(
0, memcmp(expected_output, output, length * sizeof(expected_output[0])));
}
} // namespace
TEST(FIRFilterTest, FilterAsIdentity) {
const float kCoefficients[] = {1.f, 0.f, 0.f, 0.f, 0.f};
float output[kInputLength];
std::unique_ptr<FIRFilter> filter(
CreateFirFilter(kCoefficients, kCoefficientsLength, kInputLength));
filter->Filter(kInput, kInputLength, output);
VerifyOutput(kInput, output, kInputLength);
}
TEST(FIRFilterTest, FilterUsedAsScalarMultiplication) {
const float kCoefficients[] = {5.f, 0.f, 0.f, 0.f, 0.f};
float output[kInputLength];
std::unique_ptr<FIRFilter> filter(
CreateFirFilter(kCoefficients, kCoefficientsLength, kInputLength));
filter->Filter(kInput, kInputLength, output);
EXPECT_FLOAT_EQ(5.f, output[0]);
EXPECT_FLOAT_EQ(20.f, output[3]);
EXPECT_FLOAT_EQ(25.f, output[4]);
EXPECT_FLOAT_EQ(50.f, output[kInputLength - 1]);
}
TEST(FIRFilterTest, FilterUsedAsInputShifting) {
const float kCoefficients[] = {0.f, 0.f, 0.f, 0.f, 1.f};
float output[kInputLength];
std::unique_ptr<FIRFilter> filter(
CreateFirFilter(kCoefficients, kCoefficientsLength, kInputLength));
filter->Filter(kInput, kInputLength, output);
EXPECT_FLOAT_EQ(0.f, output[0]);
EXPECT_FLOAT_EQ(0.f, output[3]);
EXPECT_FLOAT_EQ(1.f, output[4]);
EXPECT_FLOAT_EQ(2.f, output[5]);
EXPECT_FLOAT_EQ(6.f, output[kInputLength - 1]);
}
TEST(FIRFilterTest, FilterUsedAsArbitraryWeighting) {
float output[kInputLength];
std::unique_ptr<FIRFilter> filter(
CreateFirFilter(kCoefficients, kCoefficientsLength, kInputLength));
filter->Filter(kInput, kInputLength, output);
EXPECT_FLOAT_EQ(0.2f, output[0]);
EXPECT_FLOAT_EQ(3.4f, output[3]);
EXPECT_FLOAT_EQ(5.21f, output[4]);
EXPECT_FLOAT_EQ(7.02f, output[5]);
EXPECT_FLOAT_EQ(14.26f, output[kInputLength - 1]);
}
TEST(FIRFilterTest, FilterInLengthLesserOrEqualToCoefficientsLength) {
float output[kInputLength];
std::unique_ptr<FIRFilter> filter(
CreateFirFilter(kCoefficients, kCoefficientsLength, 2));
filter->Filter(kInput, 2, output);
EXPECT_FLOAT_EQ(0.2f, output[0]);
EXPECT_FLOAT_EQ(0.7f, output[1]);
filter.reset(
CreateFirFilter(kCoefficients, kCoefficientsLength, kCoefficientsLength));
filter->Filter(kInput, kCoefficientsLength, output);
EXPECT_FLOAT_EQ(0.2f, output[0]);
EXPECT_FLOAT_EQ(3.4f, output[3]);
EXPECT_FLOAT_EQ(5.21f, output[4]);
}
TEST(FIRFilterTest, MultipleFilterCalls) {
float output[kInputLength];
std::unique_ptr<FIRFilter> filter(
CreateFirFilter(kCoefficients, kCoefficientsLength, 3));
filter->Filter(kInput, 2, output);
EXPECT_FLOAT_EQ(0.2f, output[0]);
EXPECT_FLOAT_EQ(0.7f, output[1]);
filter->Filter(kInput, 2, output);
EXPECT_FLOAT_EQ(1.3f, output[0]);
EXPECT_FLOAT_EQ(2.4f, output[1]);
filter->Filter(kInput, 2, output);
EXPECT_FLOAT_EQ(2.81f, output[0]);
EXPECT_FLOAT_EQ(2.62f, output[1]);
filter->Filter(kInput, 2, output);
EXPECT_FLOAT_EQ(2.81f, output[0]);
EXPECT_FLOAT_EQ(2.62f, output[1]);
filter->Filter(&kInput[3], 3, output);
EXPECT_FLOAT_EQ(3.41f, output[0]);
EXPECT_FLOAT_EQ(4.12f, output[1]);
EXPECT_FLOAT_EQ(6.21f, output[2]);
filter->Filter(&kInput[3], 3, output);
EXPECT_FLOAT_EQ(8.12f, output[0]);
EXPECT_FLOAT_EQ(9.14f, output[1]);
EXPECT_FLOAT_EQ(9.45f, output[2]);
}
TEST(FIRFilterTest, VerifySampleBasedVsBlockBasedFiltering) {
float output_block_based[kInputLength];
std::unique_ptr<FIRFilter> filter(
CreateFirFilter(kCoefficients, kCoefficientsLength, kInputLength));
filter->Filter(kInput, kInputLength, output_block_based);
float output_sample_based[kInputLength];
filter.reset(CreateFirFilter(kCoefficients, kCoefficientsLength, 1));
for (size_t i = 0; i < kInputLength; ++i) {
filter->Filter(&kInput[i], 1, &output_sample_based[i]);
}
EXPECT_EQ(0, memcmp(output_sample_based, output_block_based, kInputLength));
}
TEST(FIRFilterTest, SimplestHighPassFilter) {
const float kCoefficients[] = {1.f, -1.f};
const size_t kCoefficientsLength =
sizeof(kCoefficients) / sizeof(kCoefficients[0]);
float kConstantInput[] = {1.f, 1.f, 1.f, 1.f, 1.f, 1.f, 1.f, 1.f};
const size_t kConstantInputLength =
sizeof(kConstantInput) / sizeof(kConstantInput[0]);
float output[kConstantInputLength];
std::unique_ptr<FIRFilter> filter(CreateFirFilter(
kCoefficients, kCoefficientsLength, kConstantInputLength));
filter->Filter(kConstantInput, kConstantInputLength, output);
EXPECT_FLOAT_EQ(1.f, output[0]);
for (size_t i = kCoefficientsLength - 1; i < kConstantInputLength; ++i) {
EXPECT_FLOAT_EQ(0.f, output[i]);
}
}
TEST(FIRFilterTest, SimplestLowPassFilter) {
const float kCoefficients[] = {1.f, 1.f};
const size_t kCoefficientsLength =
sizeof(kCoefficients) / sizeof(kCoefficients[0]);
float kHighFrequencyInput[] = {-1.f, 1.f, -1.f, 1.f, -1.f, 1.f, -1.f, 1.f};
const size_t kHighFrequencyInputLength =
sizeof(kHighFrequencyInput) / sizeof(kHighFrequencyInput[0]);
float output[kHighFrequencyInputLength];
std::unique_ptr<FIRFilter> filter(CreateFirFilter(
kCoefficients, kCoefficientsLength, kHighFrequencyInputLength));
filter->Filter(kHighFrequencyInput, kHighFrequencyInputLength, output);
EXPECT_FLOAT_EQ(-1.f, output[0]);
for (size_t i = kCoefficientsLength - 1; i < kHighFrequencyInputLength; ++i) {
EXPECT_FLOAT_EQ(0.f, output[i]);
}
}
TEST(FIRFilterTest, SameOutputWhenSwapedCoefficientsAndInput) {
float output[kCoefficientsLength];
float output_swaped[kCoefficientsLength];
std::unique_ptr<FIRFilter> filter(
CreateFirFilter(kCoefficients, kCoefficientsLength, kCoefficientsLength));
// Use kCoefficientsLength for in_length to get same-length outputs.
filter->Filter(kInput, kCoefficientsLength, output);
filter.reset(
CreateFirFilter(kInput, kCoefficientsLength, kCoefficientsLength));
filter->Filter(kCoefficients, kCoefficientsLength, output_swaped);
for (size_t i = 0; i < kCoefficientsLength; ++i) {
EXPECT_FLOAT_EQ(output[i], output_swaped[i]);
}
}
} // namespace webrtc