Audio/video data streaming over shared memory.

chromecast/media/cma/ipc_streamer/coded_frame_provider_host.cc

+// Copyright 2014 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/ipc_streamer/coded_frame_provider_host.h"
+
+#include "base/bind.h"
+#include "base/callback_helpers.h"
+#include "chromecast/media/cma/base/decoder_buffer_base.h"
+#include "chromecast/media/cma/ipc/media_message.h"
+#include "chromecast/media/cma/ipc/media_message_fifo.h"
+#include "chromecast/media/cma/ipc/media_message_type.h"
+#include "chromecast/media/cma/ipc_streamer/audio_decoder_config_marshaller.h"
+#include "chromecast/media/cma/ipc_streamer/decoder_buffer_base_marshaller.h"
+#include "chromecast/media/cma/ipc_streamer/video_decoder_config_marshaller.h"
+#include "media/base/buffers.h"
+#include "media/base/decrypt_config.h"
+
+namespace chromecast {
+namespace media {
+
+CodedFrameProviderHost::CodedFrameProviderHost(
+    scoped_ptr<MediaMessageFifo> media_message_fifo)
+  : fifo_(media_message_fifo.Pass()),
+    weak_factory_(this),
+    weak_this_(weak_factory_.GetWeakPtr()) {
+  thread_checker_.DetachFromThread();
+}
+
+CodedFrameProviderHost::~CodedFrameProviderHost() {
+  DCHECK(thread_checker_.CalledOnValidThread());
+}
+
+void CodedFrameProviderHost::Read(const ReadCB& read_cb) {
+  DCHECK(thread_checker_.CalledOnValidThread());
+
+  // Cannot be called if there is already a pending read.
+  DCHECK(read_cb_.is_null());
+  read_cb_ = read_cb;
+
+  ReadMessages();
+}
+
+void CodedFrameProviderHost::Flush(const base::Closure& flush_cb) {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  audio_config_ = ::media::AudioDecoderConfig();
+  video_config_ = ::media::VideoDecoderConfig();
+  read_cb_.Reset();
+  fifo_->Flush();
+  flush_cb.Run();
+}
+
+void CodedFrameProviderHost::OnFifoWriteEvent() {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  ReadMessages();
+}
+
+base::Closure CodedFrameProviderHost::GetFifoWriteEventCb() {
+  return base::Bind(&CodedFrameProviderHost::OnFifoWriteEvent, weak_this_);
+}
+
+void CodedFrameProviderHost::ReadMessages() {
+  // Read messages until a frame is provided (i.e. not just the audio/video
+  // configurations).
+  while (!read_cb_.is_null()) {
+    scoped_ptr<MediaMessage> msg(fifo_->Pop());
+    if (!msg)
+      break;
+
+    if (msg->type() == PaddingMediaMsg) {
+      // Ignore the message.
+    } else if (msg->type() == AudioConfigMediaMsg) {
+      audio_config_ = AudioDecoderConfigMarshaller::Read(msg.get());
+    } else if (msg->type() == VideoConfigMediaMsg) {
+      video_config_ = VideoDecoderConfigMarshaller::Read(msg.get());
+    } else if (msg->type() == FrameMediaMsg) {
+      scoped_refptr<DecoderBufferBase> buffer =
+          DecoderBufferBaseMarshaller::Read(msg.Pass());
+      base::ResetAndReturn(&read_cb_).Run(
+          buffer, audio_config_, video_config_);
+      audio_config_ = ::media::AudioDecoderConfig();
+      video_config_ = ::media::VideoDecoderConfig();
+    } else {
+      LOG(FATAL) << "Unknown media message";

[gunsch, 2014/09/10 18:51:37]

NOTREACHED

[damienv1, 2014/09/10 21:24:54]

No. Entering this use case might mean the renderer process has been compromised
(and the attacker tries to send invalid data over IPC).
In order to avoid any other potential security issue, we'd rather crash the
browser process (just like we use CHECK when we validate the audio codec in
AudioDecoderConfigMarshaller for e.g.).

I added a comment though.

+    }
+  }
+}
+
+}  // namespace media
+}  // namespace chromecast