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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 "ambisonics/stereo_from_soundfield_converter.h"
#include <iterator>
#include "third_party/googletest/googletest/include/gtest/gtest.h"
#include "base/audio_buffer.h"
#include "base/constants_and_types.h"
#include "utils/planar_interleaved_conversion.h"
namespace vraudio {
namespace {
// Number of frames per buffer.
const size_t kFramesPerBuffer = 2;
// First order ambisonic signal in the AmbiX format (W, Y, Z, X), sound source
// in the front.
const float kFirstOrderSourceFront[] = {1.0f, 0.0f, 0.0f, 1.0f,
1.0f, 0.0f, 0.0f, 1.0f};
// First order ambisonic signal in the AmbiX format (W, Y, Z, X), sound source
// to the left.
const float kFirstOrderSourceLeft[] = {1.0f, 1.0f, 0.0f, 0.0f,
1.0f, 1.0f, 0.0f, 0.0f};
// Tests whether the conversion to stereo from soundfield results in equal
// signal in both L/R output channels when there is a single source in front of
// the soundfield.
TEST(StereoFromSoundfieldConverterTest, StereoFromSoundfieldFrontTest) {
// Initialize the soundfield input buffer.
const std::vector<float> soundfield_data(std::begin(kFirstOrderSourceFront),
std::end(kFirstOrderSourceFront));
AudioBuffer soundfield_buffer(
kNumFirstOrderAmbisonicChannels,
soundfield_data.size() / kNumFirstOrderAmbisonicChannels);
FillAudioBuffer(soundfield_data, kNumFirstOrderAmbisonicChannels,
&soundfield_buffer);
// Output buffer is stereo.
AudioBuffer output(kNumStereoChannels,
soundfield_data.size() / kNumFirstOrderAmbisonicChannels);
StereoFromSoundfield(soundfield_buffer, &output);
// Test for near equality.
ASSERT_EQ(kNumStereoChannels, output.num_channels());
const AudioBuffer::Channel& output_channel_left = output[0];
const AudioBuffer::Channel& output_channel_right = output[1];
for (size_t frame = 0; frame < kFramesPerBuffer; ++frame) {
EXPECT_NEAR(output_channel_left[frame], output_channel_right[frame],
kEpsilonFloat);
}
}
// Tests whether the conversion to stereo from soundfield, when the sound source
// in the soundfield is to the left, results in a signal only in the L output
// channel.
TEST(StereoFromSoundfieldConverterTest, StereoFromSoundfieldLeftTest) {
// Initialize the soundfield input buffer.
const std::vector<float> soundfield_data(std::begin(kFirstOrderSourceLeft),
std::end(kFirstOrderSourceLeft));
AudioBuffer soundfield_buffer(
kNumFirstOrderAmbisonicChannels,
soundfield_data.size() / kNumFirstOrderAmbisonicChannels);
FillAudioBuffer(soundfield_data, kNumFirstOrderAmbisonicChannels,
&soundfield_buffer);
// Output buffer is stereo.
AudioBuffer output(kNumStereoChannels,
soundfield_data.size() / kNumFirstOrderAmbisonicChannels);
StereoFromSoundfield(soundfield_buffer, &output);
// Test for near equality.
ASSERT_EQ(kNumStereoChannels, output.num_channels());
const AudioBuffer::Channel& output_channel_left = output[0];
const AudioBuffer::Channel& output_channel_right = output[1];
for (size_t frame = 0; frame < kFramesPerBuffer; ++frame) {
EXPECT_NEAR(output_channel_left[frame], 1.0f, kEpsilonFloat);
EXPECT_NEAR(output_channel_right[frame], 0.0f, kEpsilonFloat);
}
}
} // namespace
} // namespace vraudio
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