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

chromecast/media/cma/backend/alsa/post_processing_pipeline_parser.cc

+// 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.
+
+#include "chromecast/media/cma/backend/alsa/post_processing_pipeline_parser.h"
+
+#include "base/files/file_path.h"
+#include "base/files/file_util.h"
+#include "base/logging.h"
+#include "chromecast/base/serializers.h"
+#include "chromecast/media/base/audio_device_ids.h"
+#include "media/audio/audio_device_description.h"
+
+namespace chromecast {
+namespace media {
+
+namespace {
+
+const base::FilePath::CharType kPostProcessingPipelineFilePath[] =
+    FILE_PATH_LITERAL("/etc/cast_audio.json");
+
+const char kCommunicationPipelineKey[] = "communication";
+const char kAlarmPipelineKey[] = "alarm";
+const char kTtsPipelineKey[] = "tts";
+const char kMediaPipelineKey[] = "media";
+
+// TODO(bshaya): Use AudioContentType instead.
+std::string GetPipelineKey(const std::string& device_id) {
+  if (device_id == ::media::AudioDeviceDescription::kCommunicationsDeviceId) {
+    return kCommunicationPipelineKey;
+  }
+  if (device_id == kAlarmAudioDeviceId) {
+    return kAlarmPipelineKey;
+  }
+  if (device_id == kTtsAudioDeviceId) {
+    return kTtsPipelineKey;
+  }
+  if (device_id == ::media::AudioDeviceDescription::kDefaultDeviceId) {
+    return kMediaPipelineKey;
+  }
+  NOTREACHED() << "Invalid device_id: " << device_id;
+  return "";
+}
+
+}  // namespace
+
+PostProcessingPipelineParser::PostProcessingPipelineParser() = default;
+PostProcessingPipelineParser::~PostProcessingPipelineParser() = default;
+
+void PostProcessingPipelineParser::Initialize() {
+  if (!base::PathExists(base::FilePath(kPostProcessingPipelineFilePath))) {
+    LOG(WARNING) << "No post-processing config found in "
+                 << kPostProcessingPipelineFilePath << ".";
+  }
+
+  cast_audio_config_data_ =
+      DeserializeJsonFromFile(base::FilePath(kPostProcessingPipelineFilePath));
+  base::DictionaryValue* audio_cfg_dict;
+  CHECK(cast_audio_config_data_->GetAsDictionary(&audio_cfg_dict))
+      << "JSON formatting error in " << kPostProcessingPipelineFilePath;
+
+  CHECK(audio_cfg_dict->GetDictionary("post_processing", &pipeline_dict_))
+      << "No \"post_processing\" object found in "
+      << kPostProcessingPipelineFilePath;
+}
+
+base::ListValue* PostProcessingPipelineParser::GetPipelineByDeviceId(
+    const std::string& device_id) {
+  if (!pipeline_dict_) {
+    return nullptr;
+  }
+
+  base::ListValue* out_list;
+  std::string key = GetPipelineKey(device_id);
+  if (!pipeline_dict_->GetList(key, &out_list)) {
+    LOG(WARNING) << "No post-processor description found for \"" << key
+                 << "\" in " << kPostProcessingPipelineFilePath
+                 << ". Using passthrough.";
+    return nullptr;
+  }
+  return out_list;
+}
+
+}  // namepsace media
+}  // namespace chromecast