Motown: Framework parts for mojo transport (producer/consumer/mediapipe) and control (audiotrack).

services/media/framework_mojo/audio_track_controller.cc

+// Copyright 2016 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 <list>
+
+#include "base/bind_helpers.h"
+#include "base/logging.h"
+#include "mojo/services/media/audio/interfaces/audio_server.mojom.h"
+#include "mojo/services/media/audio/interfaces/audio_track.mojom.h"
+#include "mojo/services/media/common/cpp/linear_transform.h"
+#include "mojo/services/media/common/cpp/local_time.h"
+#include "services/media/framework/conversion_pipeline_builder.h"
+#include "services/media/framework_mojo/audio_track_controller.h"
+#include "services/media/framework_mojo/mojo_type_conversions.h"
+
+namespace mojo {
+namespace media {
+
+AudioTrackController::AudioTrackController(
+    const String& url,
+    std::unique_ptr<StreamType> stream_type,
+    Graph* graph,
+    OutputRef output,
+    ApplicationImpl* app,
+    const ConstructorCallback& callback) {
+  DCHECK(stream_type);
+  DCHECK(graph);
+  DCHECK(output);
+  DCHECK(app);
+
+  AudioServerPtr audio_server;
+  app->ConnectToService(url, &audio_server);
+  audio_server->CreateTrack(GetProxy(&audio_track_));
+
+  // TODO(dalesat): Remove capture hack once c++14 is happening.
+  std::shared_ptr<StreamType> captured_stream_type(stream_type.release());
+
+  // Query the track's format capabilities.
+  audio_track_->Describe(
+    [this, callback, captured_stream_type, graph, output]
+    (AudioTrackDescriptorPtr descriptor) {
+      std::unique_ptr<StreamType> producer_stream_type;
+
+      // Add transforms to the pipeline to convert from stream_type to a type
+      // supported by the track.
+      OutputRef out = output;
+      bool result = BuildConversionPipeline(
+          *captured_stream_type,
+          *Convert(descriptor->supported_media_types),
+          graph,
+          &out,
+          &producer_stream_type);
+      if (!result) {
+        // Failed to build conversion pipeline.
+        callback.Run(nullptr);
+        return;
+      }
+
+      switch (producer_stream_type->scheme()) {
+        case StreamType::Scheme::kLpcm:
+          frames_per_second_ =
+              producer_stream_type->lpcm()->frames_per_second();
+          break;
+        case StreamType::Scheme::kCompressedAudio:
+          frames_per_second_ =
+              producer_stream_type->compressed_audio()->frames_per_second();
+          break;
+        default:
+          // Unsupported producer stream type.
+          callback.Run(nullptr);
+          return;
+      }
+
+      AudioTrackConfigurationPtr config = AudioTrackConfiguration::New();
+      config->media_type = Convert(std::move(producer_stream_type));
+
+      audio_track_->Configure(config.Pass(), GetProxy(&pipe_));
+
+      std::shared_ptr<AudioTrackProducer> sink =
+          AudioTrackProducer::Create(pipe_.Pass());
+      graph->ConnectOutputToPart(out, graph->Add(sink));
+      callback.Run(sink);
+    });
+}
+
+AudioTrackController::~AudioTrackController() {}
+
+void AudioTrackController::SetRate(
+    float rate_factor,
+    const SetRateCallback& callback) {
+  // TODO(dalesat): Set the rate at a particular local time to coordinate rate
+  // changes for multiple outputs.
+  // TODO(dalesat): Need to specify the starting media time for seek and for
+  // sources that don't start at zero.
+  if (!rate_control_.is_bound()) {
+    audio_track_->GetRateControl(GetProxy(&rate_control_));
+  }
+
+  LinearTransform::Ratio audio_rate(
+      static_cast<uint32_t>(frames_per_second_ * rate_factor), 1);
+  LinearTransform::Ratio local_time_rate(
+      LocalDuration::period::num,
+      LocalDuration::period::den);
+
+  LinearTransform::Ratio rate;
+  bool success =
+      LinearTransform::Ratio::Compose(local_time_rate, audio_rate, &rate);
+  DCHECK(success)
+      << "LinearTransform::Ratio::Compose reports loss of precision";
+
+  rate_control_->SetRate(rate.numerator, rate.denominator);
+
+  // TODO(dalesat): Replace this with a clock.
+  // The code below produces a transform that translates local time into media
+  // time in nanosecond units. That transform is delivered to the application,
+  // which uses it to implement a progress bar. This is OK for demo purposes,
+  // but we really need a clock rather than this static transform.
+  rate_control_->GetCurrentTransform(
+    [this, callback](TimelineTransformPtr transform) {
+      // Get the frame rate in local duration units.
+      LinearTransform::Ratio audio_rate(frames_per_second_, 1);
+      LinearTransform::Ratio local_time_rate(
+          LocalDuration::period::num,
+          LocalDuration::period::den);
+      LinearTransform::Ratio presentation_rate;
+      bool success = LinearTransform::Ratio::Compose(
+          local_time_rate,
+          audio_rate,
+          &presentation_rate);
+      DCHECK(success)
+          << "LinearTransform::Ratio::Compose reports loss of precision";
+
+      // Create a LinearTransform to translate from presentation units to
+      // local duration units.
+      LinearTransform local_to_presentation(0, presentation_rate, 0);
+
+      // Translate the current transform quad so the presentation time units
+      // are the same as the local time units.
+      success = local_to_presentation.DoReverseTransform(
+          transform->quad->reference_offset,
+          &transform->quad->reference_offset);
+      DCHECK(success)
+          << "LinearTransform::DoReverseTransform reports loss of precision";
+      int64_t presentation_delta;
+      success = local_to_presentation.DoReverseTransform(
+          static_cast<int64_t>(transform->quad->reference_delta),
+          &presentation_delta);
+      DCHECK(success)
+          << "LinearTransform::DoReverseTransform reports loss of precision";
+      transform->quad->reference_delta =
+          static_cast<int32_t>(presentation_delta);
+      LinearTransform::Ratio::Reduce(
+          &transform->quad->reference_delta,
+          &transform->quad->target_delta);
+
+      callback(transform.Clone());
+    });
+}
+
+} // namespace media
+} // namespace mojo