Implement runtime audio post-processing pipeline. See go/cast_audio.json

chromecast/media/cma/backend/alsa/post_processing_pipeline.h

+// Copyright 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef CHROMECAST_MEDIA_CMA_BACKEND_ALSA_POST_PROCESSING_PIPELINE_H_
+#define CHROMECAST_MEDIA_CMA_BACKEND_ALSA_POST_PROCESSING_PIPELINE_H_
+
+#include <cstdint>
+#include <memory>
+#include <string>
+#include <unordered_map>
+#include <vector>
+
+#include "base/macros.h"
+#include "base/scoped_native_library.h"
+
+namespace base {
+class ListValue;
+}  // namespace base
+
+namespace chromecast {
+namespace media {
+
+class AudioPostProcessor;
+
+// Creates and contains multiple AudioPostProcessors, as specified in ctor.
+// Provides convenience methods to access and use the AudioPostProcessors.
+class PostProcessingPipeline {
+ public:
+  PostProcessingPipeline(const base::ListValue* filter_description_list,
+                         int channels);
+  ~PostProcessingPipeline();
+
+  // TODO(bshaya): Switch to float*
+  int ProcessFrames(uint8_t* data,
+                    int num_frames,
+                    float current_volume,
+                    bool is_silence);
+  bool SetSampleRate(int sample_rate);
+  bool IsRinging();
+
+ private:
+  int GetRingingTimeInFrames();
+
+  int sample_rate_;
+  int ringing_time_in_frames_ = 0;
+  int silence_frames_processed_ = 0;
+  int total_delay_frames_ = 0;
+  std::vector<std::unique_ptr<AudioPostProcessor>> processors_;
+
+  // Contains all libraries in use;
+  // Functions in shared objects cannot be used once library is closed.
+  std::unordered_map<std::string, std::unique_ptr<base::ScopedNativeLibrary>>

[wzhong, 2017/03/24 19:22:29]

map is not necessary as I've commented in the internal review.

[bshaya, 2017/03/24 21:32:25]

Done.

+      libraries_;
+
+  DISALLOW_COPY_AND_ASSIGN(PostProcessingPipeline);
+};
+
+}  // namespace media
+}  // namespace chromecast
+
+#endif  // CHROMECAST_MEDIA_CMA_BACKEND_ALSA_POST_PROCESSING_PIPELINE_H_