Chromecast: Play audio streams not supported by CMA via default renderer

chromecast/renderer/media/chromecast_media_renderer_factory.cc

+// Copyright 2014 The Chromium Authors. All rights reserved.

[gunsch, 2015/03/03 00:06:40]

2015

[servolk, 2015/03/03 00:46:53]

Done.

+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "chromecast/renderer/media/chromecast_media_renderer_factory.h"
+
+#include "base/command_line.h"
+#include "chromecast/media/base/media_renderer.h"
+#include "chromecast/media/cma/filters/cma_renderer.h"
+#include "chromecast/renderer/media/media_pipeline_proxy.h"
+#include "content/public/renderer/render_thread.h"
+#include "media/base/audio_hardware_config.h"
+#include "media/base/media_log.h"
+#include "media/renderers/default_renderer_factory.h"
+
+namespace chromecast {
+namespace media {
+
+ChromecastMediaRendererFactory::ChromecastMediaRendererFactory(
+    const scoped_refptr<::media::MediaLog>& media_log,
+    int render_frame_id)
+    : render_frame_id_(render_frame_id),
+      media_log_(media_log) {
+}
+
+ChromecastMediaRendererFactory::~ChromecastMediaRendererFactory() {
+}
+
+scoped_ptr<::media::Renderer> ChromecastMediaRendererFactory::CreateRenderer(
+    const scoped_refptr<base::SingleThreadTaskRunner>& media_task_runner,
+    ::media::AudioRendererSink* audio_renderer_sink) {
+  if (!default_render_factory_) {
+    // Chromecast doesn't have input audio devices, so leave this uninitialized
+    ::media::AudioParameters input_audio_params;
+    // TODO(servolk): Audio parameters are hardcoded for now, but in the future
+    // either we need to obtain AudioHardwareConfig from RenderThreadImpl,
+    // or media renderer needs to figure out optimal audio parameters itself.
+    const int kDefaultSamplingRate = 48000;
+    const int kDefaultBitsPerSample = 16;
+    int buffer_size = kDefaultSamplingRate*20*2/1000; // About 20ms of audio

[gunsch, 2015/03/03 00:06:40]

style nit: spaces on sides of operators

[servolk, 2015/03/03 00:46:53]

Done.

+    ::media::AudioParameters output_audio_params(
+        ::media::AudioParameters::AUDIO_PCM_LOW_LATENCY,
+        ::media::CHANNEL_LAYOUT_STEREO,
+        kDefaultSamplingRate, kDefaultBitsPerSample,
+        buffer_size, ::media::AudioParameters::NO_EFFECTS);
+    ::media::AudioHardwareConfig audio_config(input_audio_params,
+                                              output_audio_params);
+
+    default_render_factory_.reset(new ::media::DefaultRendererFactory(
+        media_log_, /*gpu_factories*/ NULL, audio_config));
+  }

[gunsch, 2015/03/03 00:06:40]

style nit: blank line after conditional block

[servolk, 2015/03/03 01:06:10]

Done.

+  DCHECK(default_render_factory_);
+  // TODO(erickung): crbug.com/443956. Need to provide right LoadType.
+  LoadType cma_load_type = kLoadTypeMediaSource;
+  scoped_ptr<MediaPipeline> cma_media_pipeline(
+      new MediaPipelineProxy(
+          render_frame_id_,
+          content::RenderThread::Get()->GetIOMessageLoopProxy(),
+          cma_load_type));
+  scoped_ptr<CmaRenderer> cma_renderer(
+      new CmaRenderer(cma_media_pipeline.Pass()));
+  scoped_ptr<::media::Renderer> default_chrome_render(

[gunsch, 2015/03/03 00:06:41]

conceptual layering violation: "chrome" is not supposed to be referenced outside
of src/chrome/

[servolk, 2015/03/03 00:46:53]

Wait, why is there a layering violation? "chrome" is only in the variable name.
I meant "chrome" as opposed to "chromecast", we could rename it to
default_media_renderer.

[gunsch, 2015/03/03 01:00:51]

Hmm, I thought I saw somewhere that you weren't supposed to mention "chrome"
outside of the src/chrome/ directory, but I can't find it now. Carry on!

+      default_render_factory_->CreateRenderer(media_task_runner,
+                                              audio_renderer_sink));
+  scoped_ptr<MediaRenderer> media_renderer(new MediaRenderer(
+      default_chrome_render.Pass(), cma_renderer.Pass()));
+  return media_renderer.Pass();
+}
+
+}  // namespace media
+}  // namespace chromecast