Motown in-proc streaming framework used to implement media services.

services/media/framework/stages/packet_transform_stage.cc

Index: services/media/framework/stages/packet_transform_stage.cc
diff --git a/services/media/framework/stages/packet_transform_stage.cc b/services/media/framework/stages/packet_transform_stage.cc
new file mode 100644
index 0000000000000000000000000000000000000000..2564f123f23933dbe2c790bd954cb2ce0b144c4e
--- /dev/null
+++ b/services/media/framework/stages/packet_transform_stage.cc
@@ -0,0 +1,73 @@
+// 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 "services/media/framework/stages/packet_transform_stage.h"
+
+namespace mojo {
+namespace media {
+
+PacketTransformStage::PacketTransformStage(
+    PacketTransformPtr transform) :
+    transform_(transform),
+    allocator_(nullptr),
+    input_packet_is_new_(true) {
+  DCHECK(transform_);
+}
+
+PacketTransformStage::~PacketTransformStage() {}
+
+uint32_t PacketTransformStage::input_count() const {
+  return 1;
+};
+
+StageInput& PacketTransformStage::input(uint32_t index) {
+  DCHECK_EQ(index, 0u);
+  return input_;
+}
+
+uint32_t PacketTransformStage::output_count() const {
+  return 1;
+}
+
+StageOutput& PacketTransformStage::output(uint32_t index) {
+  DCHECK_EQ(index, 0u);
+  return output_;
+}
+
+bool PacketTransformStage::Prepare(const UpdateCallback update_callback) {
+  allocator_ = output_.Prepare(true);
+  if (allocator_ == nullptr) {
+    allocator_ = Allocator::GetDefault();
+  }
+  input_.Prepare(nullptr, false);
+  return false;
+}
+
+void PacketTransformStage::Update(Engine* engine) {
+  DCHECK(engine);
+  DCHECK(allocator_);
+
+  if (input_.packet_from_upstream() && output_.demand() != Demand::kNegative) {
+    PacketPtr output_packet;
+    if (transform_->TransformPacket(
+        input_.packet_from_upstream(),
+        input_packet_is_new_,
+        allocator_,
+        &output_packet)) {
+      input_.packet_from_upstream().reset();
+      input_packet_is_new_ = true;
+    } else {
+      input_packet_is_new_ = false;
+    }
+
+    if (output_packet) {
+      output_.SupplyPacket(std::move(output_packet), engine);
+    }
+  }
+
+  input_.SetDemand(output_.demand(), engine);
+}
+
+}  // namespace media
+}  // namespace mojo