ambisonic_mixing_encoder_node.cc

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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 "graph/ambisonic_mixing_encoder_node.h"

#include "ambisonics/utils.h"

#include "base/constants_and_types.h"

#include "base/logging.h"

namespace vraudio {

AmbisonicMixingEncoderNode::AmbisonicMixingEncoderNode(

    const SystemSettings& system_settings,

    const AmbisonicLookupTable& lookup_table, int ambisonic_order)

    : system_settings_(system_settings),

      lookup_table_(lookup_table),

      ambisonic_order_(ambisonic_order),

      gain_mixer_(GetNumPeriphonicComponents(ambisonic_order_),

                  system_settings_.GetFramesPerBuffer()),

      coefficients_(GetNumPeriphonicComponents(ambisonic_order_)) {}

const AudioBuffer* AmbisonicMixingEncoderNode::AudioProcess(

    const NodeInput& input) {

  const WorldPosition& listener_position = system_settings_.GetHeadPosition();

  const WorldRotation& listener_rotation = system_settings_.GetHeadRotation();

  gain_mixer_.Reset();

  for (auto& input_buffer : input.GetInputBuffers()) {

    const int source_id = input_buffer->source_id();

    const auto source_parameters =

        system_settings_.GetSourceParameters(source_id);

    DCHECK_NE(source_id, kInvalidSourceId);

    DCHECK_EQ(input_buffer->num_channels(), 1U);

    // Compute the relative source direction in spherical angles.

    const ObjectTransform& source_transform =

        source_parameters->object_transform;

    WorldPosition relative_direction;

    GetRelativeDirection(listener_position, listener_rotation,

                         source_transform.position, &relative_direction);

    const SphericalAngle source_direction =

        SphericalAngle::FromWorldPosition(relative_direction);

    lookup_table_.GetEncodingCoeffs(ambisonic_order_, source_direction,

                                    source_parameters->spread_deg,

                                    &coefficients_);

    gain_mixer_.AddInputChannel((*input_buffer)[0], source_id, coefficients_);

  return gain_mixer_.GetOutput();

}  // namespace vraudio