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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.
*/
#if defined(_WIN32)
#define _SCL_SECURE_NO_WARNINGS
#endif
#include "ambisonics/foa_rotator.h"
#include <algorithm>
#include "base/constants_and_types.h"
#include "base/misc_math.h"
namespace vraudio {
bool FoaRotator::Process(const WorldRotation& target_rotation,
const AudioBuffer& input, AudioBuffer* output) {
DCHECK(output);
DCHECK_EQ(input.num_channels(), kNumFirstOrderAmbisonicChannels);
DCHECK_EQ(input.num_channels(), output->num_channels());
DCHECK_EQ(input.num_frames(), output->num_frames());
static const WorldRotation kIdentityRotation;
if (current_rotation_.AngularDifferenceRad(kIdentityRotation) <
kRotationQuantizationRad &&
target_rotation.AngularDifferenceRad(kIdentityRotation) <
kRotationQuantizationRad) {
return false;
}
if (current_rotation_.AngularDifferenceRad(target_rotation) <
kRotationQuantizationRad) {
// Rotate the whole input buffer frame by frame.
Rotate(current_rotation_, 0, input.num_frames(), input, output);
return true;
}
// In order to perform a smooth rotation, we divide the buffer into
// chunks of size |kSlerpFrameInterval|.
//
const size_t kSlerpFrameInterval = 32;
WorldRotation slerped_rotation;
// Rotate the input buffer at every slerp update interval. Truncate the
// final chunk if the input buffer is not an integer multiple of the
// chunk size.
for (size_t i = 0; i < input.num_frames(); i += kSlerpFrameInterval) {
const size_t duration =
std::min(input.num_frames() - i, kSlerpFrameInterval);
const float interpolation_factor = static_cast<float>(i + duration) /
static_cast<float>(input.num_frames());
slerped_rotation =
current_rotation_.slerp(interpolation_factor, target_rotation);
// Rotate the input buffer frame by frame within the current chunk.
Rotate(slerped_rotation, i, duration, input, output);
}
current_rotation_ = target_rotation;
return true;
}
void FoaRotator::Rotate(const WorldRotation& target_rotation,
size_t start_location, size_t duration,
const AudioBuffer& input, AudioBuffer* output) {
const AudioBuffer::Channel& input_channel_audio_space_w = input[0];
const AudioBuffer::Channel& input_channel_audio_space_y = input[1];
const AudioBuffer::Channel& input_channel_audio_space_z = input[2];
const AudioBuffer::Channel& input_channel_audio_space_x = input[3];
AudioBuffer::Channel* output_channel_audio_space_w = &(*output)[0];
AudioBuffer::Channel* output_channel_audio_space_y = &(*output)[1];
AudioBuffer::Channel* output_channel_audio_space_z = &(*output)[2];
AudioBuffer::Channel* output_channel_audio_space_x = &(*output)[3];
for (size_t frame = start_location; frame < start_location + duration;
++frame) {
// Convert the current audio frame into world space position.
temp_audio_position_(0) = input_channel_audio_space_x[frame];
temp_audio_position_(1) = input_channel_audio_space_y[frame];
temp_audio_position_(2) = input_channel_audio_space_z[frame];
ConvertWorldFromAudioPosition(temp_audio_position_, &temp_world_position_);
// Apply rotation to |world_position| and return to audio space.
temp_rotated_world_position_ = target_rotation * temp_world_position_;
ConvertAudioFromWorldPosition(temp_rotated_world_position_,
&temp_rotated_audio_position_);
(*output_channel_audio_space_x)[frame] =
temp_rotated_audio_position_(0); // X
(*output_channel_audio_space_y)[frame] =
temp_rotated_audio_position_(1); // Y
(*output_channel_audio_space_z)[frame] =
temp_rotated_audio_position_(2); // Z
}
// Copy W channel.
std::copy_n(&input_channel_audio_space_w[start_location], duration,
&(*output_channel_audio_space_w)[start_location]);
}
} // namespace vraudio
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