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/*
Copyright 2018 Google Inc. All Rights Reserved.
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS-IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/
#include "dsp/mono_pole_filter.h"
#include <cmath>
#include "third_party/googletest/googletest/include/gtest/gtest.h"
#include "base/constants_and_types.h"
#include "base/misc_math.h"
namespace vraudio {
namespace {
const float kCoefficient = 0.5f;
const size_t kFramesPerBuffer = 10;
// Tests that the filter correctly implements the difference equation.
TEST(MonoPoleFilterTest, ImpulseResponseTest) {
MonoPoleFilter filter(kCoefficient);
AudioBuffer buffer(1U, kFramesPerBuffer);
buffer.Clear();
buffer[0][0] = 1.0f;
EXPECT_TRUE(filter.Filter(buffer[0], &buffer[0]));
for (size_t i = 0; i < kFramesPerBuffer; ++i) {
// The impulse response of this filter (for coefficient a), should be:
// d[n] = (1 - a) * a^n
const float expected =
(1.0f - kCoefficient) * IntegerPow(kCoefficient, static_cast<int>(i));
EXPECT_NEAR(buffer[0][i], expected, kEpsilonFloat);
}
}
// Tests that no processing is performed when the filter is allpass.
TEST(MonoPoleFilterTest, AllPassNoProcessingTest) {
MonoPoleFilter filter(0.0f);
AudioBuffer buffer(1U, kFramesPerBuffer);
buffer.Clear();
buffer[0][0] = 1.0f;
EXPECT_FALSE(filter.Filter(buffer[0], &buffer[0]));
}
} // namespace
} // namespace vraudio
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