1 files changed, 115 insertions, 0 deletions
diff --git a/src/3rdparty/resonance-audio/resonance_audio/dsp/gain_mixer.cc b/src/3rdparty/resonance-audio/resonance_audio/dsp/gain_mixer.cc
new file mode 100644
index 000000000..06417be11
--- /dev/null
+++ b/src/3rdparty/resonance-audio/resonance_audio/dsp/gain_mixer.cc
@@ -0,0 +1,115 @@
+/*
+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/gain_mixer.h"
+
+#include <cmath>
+
+#include "base/logging.h"
+
+namespace vraudio {
+
+GainMixer::GainMixer(size_t num_channels, size_t frames_per_buffer)
+    : num_channels_(num_channels),
+      output_(num_channels_, frames_per_buffer),
+      is_empty_(false) {
+  DCHECK_NE(num_channels_, 0U);
+  Reset();
+}
+
+void GainMixer::AddInput(const AudioBuffer& input,
+                         const std::vector<float>& gains) {
+  DCHECK_EQ(gains.size(), num_channels_);
+  DCHECK_EQ(input.num_channels(), num_channels_);
+  DCHECK_EQ(input.num_frames(), output_.num_frames());
+
+  auto* gain_processors = GetOrCreateProcessors(input.source_id());
+  // Accumulate the input buffers into the output buffer.
+  for (size_t i = 0; i < num_channels_; ++i) {
+    if (input[i].IsEnabled()) {
+      (*gain_processors)[i].ApplyGain(gains[i], input[i], &output_[i],
+                                      true /* accumulate_output */);
+    } else {
+      // Make sure the gain processor is initialized.
+      (*gain_processors)[i].Reset(gains[i]);
+    }
+  }
+  is_empty_ = false;
+}
+
+void GainMixer::AddInputChannel(const AudioBuffer::Channel& input,
+                                SourceId source_id,
+                                const std::vector<float>& gains) {
+  DCHECK_EQ(gains.size(), num_channels_);
+  DCHECK_EQ(input.size(), output_.num_frames());
+
+  auto* gain_processors = GetOrCreateProcessors(source_id);
+  // Accumulate the input buffers into the output buffer.
+  for (size_t i = 0; i < num_channels_; ++i) {
+    if (input.IsEnabled()) {
+      (*gain_processors)[i].ApplyGain(gains[i], input, &output_[i],
+                                      true /* accumulate_output */);
+    } else {
+      // Make sure the gain processor is initialized.
+      (*gain_processors)[i].Reset(gains[i]);
+    }
+  }
+  is_empty_ = false;
+}
+
+const AudioBuffer* GainMixer::GetOutput() const {
+  if (is_empty_) {
+    return nullptr;
+  }
+  return &output_;
+}
+
+void GainMixer::Reset() {
+  if (!is_empty_) {
+    // Delete the processors for sources which no longer exist.
+    for (auto it = source_gain_processors_.begin();
+         it != source_gain_processors_.end();
+         /* no increment */) {
+      if (it->second.processors_active) {
+        it->second.processors_active = false;
+        ++it;
+      } else {
+        source_gain_processors_.erase(it++);
+      }
+    }
+    // Reset the output buffer.
+    output_.Clear();
+  }
+  is_empty_ = true;
+}
+
+GainMixer::GainProcessors::GainProcessors(size_t num_channels)
+    : processors_active(true), processors(num_channels) {}
+
+std::vector<GainProcessor>* GainMixer::GetOrCreateProcessors(
+    SourceId source_id) {
+  // Attempt to find a |ScaleAndAccumulateProcessor| for the given |source_id|,
+  // if none can be found add one. In either case mark that the processor has
+  // been used so that it is not later deleted.
+  if (source_gain_processors_.find(source_id) ==
+      source_gain_processors_.end()) {
+    source_gain_processors_.insert({source_id, GainProcessors(num_channels_)});
+  }
+  source_gain_processors_.at(source_id).processors_active = true;
+  return &(source_gain_processors_.at(source_id).processors);
+}
+
+}  // namespace vraudio