[Cast] Refactor/clean-up VideoReceiver to match AudioReceiver as closely as possible.

media/cast/video_receiver/video_receiver.cc

 // Copyright 2013 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 "media/cast/video_receiver/video_receiver.h"
 
 #include <algorithm>
 
 #include "base/bind.h"
 #include "base/debug/trace_event.h"
 #include "base/logging.h"
 #include "base/message_loop/message_loop.h"
-#include "media/cast/cast_defines.h"
-#include "media/cast/framer/framer.h"
-#include "media/cast/rtcp/receiver_rtcp_event_subscriber.h"
-#include "media/cast/rtcp/rtcp_sender.h"
+#include "media/base/video_frame.h"
+#include "media/cast/logging/logging_defines.h"
+#include "media/cast/transport/cast_transport_defines.h"
 #include "media/cast/video_receiver/video_decoder.h"
 
 namespace {
-
-static const int64 kMinSchedulingDelayMs = 1;
-static const int64 kMinTimeBetweenOffsetUpdatesMs = 1000;
-static const int kTimeOffsetMaxCounter = 10;
-
+const int kMinSchedulingDelayMs = 1;
+const int kMinTimeBetweenOffsetUpdatesMs = 1000;
+const int kTimeOffsetMaxCounter = 10;
 }  // namespace
 
 namespace media {
 namespace cast {
 
-// Local implementation of RtpPayloadFeedback (defined in rtp_defines.h)
-// Used to convey cast-specific feedback from receiver to sender.
-// Callback triggered by the Framer (cast message builder).
-class LocalRtpVideoFeedback : public RtpPayloadFeedback {
- public:
-  explicit LocalRtpVideoFeedback(VideoReceiver* video_receiver)
-      : video_receiver_(video_receiver) {}
-
-  virtual void CastFeedback(const RtcpCastMessage& cast_message) OVERRIDE {
-    video_receiver_->CastFeedback(cast_message);
-  }
-
- private:
-  VideoReceiver* video_receiver_;
-
-  DISALLOW_IMPLICIT_CONSTRUCTORS(LocalRtpVideoFeedback);
-};
-
 VideoReceiver::VideoReceiver(scoped_refptr<CastEnvironment> cast_environment,
                              const VideoReceiverConfig& video_config,
-                             transport::PacedPacketSender* const packet_sender,
-                             const SetTargetDelayCallback& target_delay_cb)
+                             transport::PacedPacketSender* const packet_sender)
     : RtpReceiver(cast_environment->Clock(), NULL, &video_config),
       cast_environment_(cast_environment),
       event_subscriber_(kReceiverRtcpEventHistorySize,
                         ReceiverRtcpEventSubscriber::kVideoEventSubscriber),
       codec_(video_config.codec),
       target_delay_delta_(
           base::TimeDelta::FromMilliseconds(video_config.rtp_max_delay_ms)),
-      frame_delay_(base::TimeDelta::FromMilliseconds(
-          1000 / video_config.max_frame_rate)),
-      incoming_payload_feedback_(new LocalRtpVideoFeedback(this)),
+      expected_frame_duration_(
+          base::TimeDelta::FromSeconds(1) / video_config.max_frame_rate),
+      framer_(cast_environment->Clock(),
+              this,
+              video_config.incoming_ssrc,
+              video_config.decoder_faster_than_max_frame_rate,
+              video_config.rtp_max_delay_ms * video_config.max_frame_rate /
+                  1000),
+      rtcp_(cast_environment_,
+            NULL,
+            NULL,
+            packet_sender,
+            GetStatistics(),
+            video_config.rtcp_mode,
+            base::TimeDelta::FromMilliseconds(video_config.rtcp_interval),
+            video_config.feedback_ssrc,
+            video_config.incoming_ssrc,
+            video_config.rtcp_c_name),
       time_offset_counter_(0),
-      decryptor_(),
       time_incoming_packet_updated_(false),
       incoming_rtp_timestamp_(0),
-      target_delay_cb_(target_delay_cb),
+      is_waiting_for_consecutive_frame_(false),
       weak_factory_(this) {
-  int max_unacked_frames =
-      video_config.rtp_max_delay_ms * video_config.max_frame_rate / 1000;
-  DCHECK(max_unacked_frames) << "Invalid argument";
-
+  DCHECK_GT(video_config.rtp_max_delay_ms, 0);
+  DCHECK_GT(video_config.max_frame_rate, 0);
+  if (!video_config.use_external_decoder) {
+    video_decoder_.reset(new VideoDecoder(cast_environment, video_config));
+  }
   decryptor_.Initialize(video_config.aes_key, video_config.aes_iv_mask);
-  framer_.reset(new Framer(cast_environment->Clock(),
-                           incoming_payload_feedback_.get(),
-                           video_config.incoming_ssrc,
-                           video_config.decoder_faster_than_max_frame_rate,
-                           max_unacked_frames));
-
-  if (!video_config.use_external_decoder) {
-    video_decoder_.reset(new VideoDecoder(video_config, cast_environment));
-  }
-
-  rtcp_.reset(
-      new Rtcp(cast_environment_,
-               NULL,
-               NULL,
-               packet_sender,
-               GetStatistics(),
-               video_config.rtcp_mode,
-               base::TimeDelta::FromMilliseconds(video_config.rtcp_interval),
-               video_config.feedback_ssrc,
-               video_config.incoming_ssrc,
-               video_config.rtcp_c_name));
-  // Set the target delay that will be conveyed to the sender.
-  rtcp_->SetTargetDelay(target_delay_delta_);
+  rtcp_.SetTargetDelay(target_delay_delta_);
   cast_environment_->Logging()->AddRawEventSubscriber(&event_subscriber_);
   memset(frame_id_to_rtp_timestamp_, 0, sizeof(frame_id_to_rtp_timestamp_));
 }
 
 VideoReceiver::~VideoReceiver() {
+  DCHECK(cast_environment_->CurrentlyOn(CastEnvironment::MAIN));
+
+  // If any callbacks for encoded video frames are queued, flush them out now.
+  // This is critical because some Closures in |frame_request_queue_| may have
+  // Unretained references to |this|.
+  while (!frame_request_queue_.empty()) {
+    frame_request_queue_.front().Run(
+        make_scoped_ptr<transport::EncodedVideoFrame>(NULL), base::TimeTicks());
+    frame_request_queue_.pop_front();
+  }
+
   cast_environment_->Logging()->RemoveRawEventSubscriber(&event_subscriber_);
 }
 
 void VideoReceiver::InitializeTimers() {
   DCHECK(cast_environment_->CurrentlyOn(CastEnvironment::MAIN));
   ScheduleNextRtcpReport();
   ScheduleNextCastMessage();
 }
 
 void VideoReceiver::GetRawVideoFrame(
     const VideoFrameDecodedCallback& callback) {
   DCHECK(cast_environment_->CurrentlyOn(CastEnvironment::MAIN));
+  DCHECK(!callback.is_null());
+  DCHECK(video_decoder_.get());
   GetEncodedVideoFrame(base::Bind(
-      &VideoReceiver::DecodeVideoFrame, base::Unretained(this), callback));
+      &VideoReceiver::DecodeEncodedVideoFrame,
+      // Note: Use of Unretained is safe since this Closure is guaranteed to be
+      // invoked before destruction of |this|.
+      base::Unretained(this),
+      callback));
 }
 
-// Called when we have a frame to decode.
-void VideoReceiver::DecodeVideoFrame(
+void VideoReceiver::DecodeEncodedVideoFrame(
     const VideoFrameDecodedCallback& callback,
     scoped_ptr<transport::EncodedVideoFrame> encoded_frame,
-    const base::TimeTicks& render_time) {
+    const base::TimeTicks& playout_time) {
+  DCHECK(cast_environment_->CurrentlyOn(CastEnvironment::MAIN));
+  if (!encoded_frame) {
+    callback.Run(make_scoped_refptr<VideoFrame>(NULL), playout_time, false);
+    return;
+  }
+  const uint32 frame_id = encoded_frame->frame_id;
+  const uint32 rtp_timestamp = encoded_frame->rtp_timestamp;
+  video_decoder_->DecodeFrame(encoded_frame.Pass(),
+                              base::Bind(&VideoReceiver::EmitRawVideoFrame,
+                                         cast_environment_,
+                                         callback,
+                                         frame_id,
+                                         rtp_timestamp,
+                                         playout_time));
+}
+
+// static
+void VideoReceiver::EmitRawVideoFrame(
+    const scoped_refptr<CastEnvironment>& cast_environment,
+    const VideoFrameDecodedCallback& callback,
+    uint32 frame_id,
+    uint32 rtp_timestamp,
+    const base::TimeTicks& playout_time,
+    const scoped_refptr<VideoFrame>& video_frame,
+    bool is_continuous) {
+  DCHECK(cast_environment->CurrentlyOn(CastEnvironment::MAIN));
+  if (video_frame) {
+    const base::TimeTicks now = cast_environment->Clock()->NowTicks();
+    cast_environment->Logging()->InsertFrameEvent(
+        now, kVideoFrameDecoded, rtp_timestamp, frame_id);
+    cast_environment->Logging()->InsertFrameEventWithDelay(
+        now, kVideoRenderDelay, rtp_timestamp, frame_id,
+        playout_time - now);
+    // Used by chrome/browser/extension/api/cast_streaming/performance_test.cc
+    TRACE_EVENT_INSTANT1(
+        "cast_perf_test", "FrameDecoded",
+        TRACE_EVENT_SCOPE_THREAD,
+        "rtp_timestamp", rtp_timestamp);
+  }
+  callback.Run(video_frame, playout_time, is_continuous);
+}
+
+void VideoReceiver::GetEncodedVideoFrame(
+    const VideoFrameEncodedCallback& callback) {
+  DCHECK(cast_environment_->CurrentlyOn(CastEnvironment::MAIN));
+  frame_request_queue_.push_back(callback);
+  EmitAvailableEncodedFrames();
+}
+
+void VideoReceiver::EmitAvailableEncodedFrames() {
   DCHECK(cast_environment_->CurrentlyOn(CastEnvironment::MAIN));
 
-  // Hand the ownership of the encoded frame to the decode thread.
-  cast_environment_->PostTask(CastEnvironment::VIDEO,
-                              FROM_HERE,
-                              base::Bind(&VideoReceiver::DecodeVideoFrameThread,
-                                         base::Unretained(this),
-                                         base::Passed(&encoded_frame),
-                                         render_time,
-                                         callback));
-}
+  while (!frame_request_queue_.empty()) {
+    // Attempt to peek at the next completed frame from the |framer_|.
+    // TODO(miu): We should only be peeking at the metadata, and not copying the
+    // payload yet!  Or, at least, peek using a StringPiece instead of a copy.
+    scoped_ptr<transport::EncodedVideoFrame> encoded_frame(
+        new transport::EncodedVideoFrame());
+    bool is_consecutively_next_frame = false;
+    if (!framer_.GetEncodedVideoFrame(encoded_frame.get(),
+                                      &is_consecutively_next_frame)) {
+      VLOG(1) << "Wait for more video packets to produce a completed frame.";
+      return;  // OnReceivedPayloadData() will invoke this method in the future.
+    }
 
-// Utility function to run the decoder on a designated decoding thread.
-void VideoReceiver::DecodeVideoFrameThread(
-    scoped_ptr<transport::EncodedVideoFrame> encoded_frame,
-    const base::TimeTicks render_time,
-    const VideoFrameDecodedCallback& frame_decoded_callback) {
-  DCHECK(cast_environment_->CurrentlyOn(CastEnvironment::VIDEO));
-  DCHECK(video_decoder_);
+    // If |framer_| has a frame ready that is out of sequence, examine the
+    // playout time to determine whether it's acceptable to continue, thereby
+    // skipping one or more frames.  Skip if the missing frame wouldn't complete
+    // playing before the start of playback of the available frame.
+    const base::TimeTicks now = cast_environment_->Clock()->NowTicks();
+    const base::TimeTicks playout_time =
+        GetPlayoutTime(now, encoded_frame->rtp_timestamp);
+    if (!is_consecutively_next_frame) {
+      // TODO(miu): Also account for expected decode time here?
+      const base::TimeTicks earliest_possible_end_time_of_missing_frame =
+          now + expected_frame_duration_;
+      if (earliest_possible_end_time_of_missing_frame < playout_time) {
+        VLOG(1) << "Wait for next consecutive frame instead of skipping.";
+        if (!is_waiting_for_consecutive_frame_) {
+          is_waiting_for_consecutive_frame_ = true;
+          cast_environment_->PostDelayedTask(
+              CastEnvironment::MAIN,
+              FROM_HERE,
+              base::Bind(&VideoReceiver::EmitAvailableEncodedFramesAfterWaiting,
+                         weak_factory_.GetWeakPtr()),
+              playout_time - now);
+        }
+        return;
+      }
+    }
 
-  if (!(video_decoder_->DecodeVideoFrame(
-           encoded_frame.get(), render_time, frame_decoded_callback))) {
-    // This will happen if we decide to decode but not show a frame.
+    // Decrypt the payload data in the frame, if crypto is being used.
+    if (decryptor_.initialized()) {
+      std::string decrypted_video_data;
+      if (!decryptor_.Decrypt(encoded_frame->frame_id,
+                              encoded_frame->data,
+                              &decrypted_video_data)) {
+        // Decryption failed.  Give up on this frame, releasing it from the
+        // jitter buffer.
+        framer_.ReleaseFrame(encoded_frame->frame_id);
+        continue;
+      }
+      encoded_frame->data.swap(decrypted_video_data);
+    }
+
+    // At this point, we have a decrypted EncodedVideoFrame ready to be emitted.
+    encoded_frame->codec = codec_;
+    framer_.ReleaseFrame(encoded_frame->frame_id);
+    // Used by chrome/browser/extension/api/cast_streaming/performance_test.cc
+    TRACE_EVENT_INSTANT2(
+        "cast_perf_test", "PullEncodedVideoFrame",
+        TRACE_EVENT_SCOPE_THREAD,
+        "rtp_timestamp", encoded_frame->rtp_timestamp,
+        // TODO(miu): Need to find an alternative to using ToInternalValue():
+        "render_time", playout_time.ToInternalValue());
     cast_environment_->PostTask(CastEnvironment::MAIN,
                                 FROM_HERE,
-                                base::Bind(&VideoReceiver::GetRawVideoFrame,
-                                           base::Unretained(this),
-                                           frame_decoded_callback));
+                                base::Bind(frame_request_queue_.front(),
+                                           base::Passed(&encoded_frame),
+                                           playout_time));
+    frame_request_queue_.pop_front();
   }
 }
 
-bool VideoReceiver::DecryptVideoFrame(
-    scoped_ptr<transport::EncodedVideoFrame>* video_frame) {
+void VideoReceiver::EmitAvailableEncodedFramesAfterWaiting() {
   DCHECK(cast_environment_->CurrentlyOn(CastEnvironment::MAIN));
-
-  if (!decryptor_.initialized())
-    return false;
-
-  std::string decrypted_video_data;
-  if (!decryptor_.Decrypt((*video_frame)->frame_id,
-                          (*video_frame)->data,
-                          &decrypted_video_data)) {
-    // Give up on this frame, release it from jitter buffer.
-    framer_->ReleaseFrame((*video_frame)->frame_id);
-    return false;
-  }
-  (*video_frame)->data.swap(decrypted_video_data);
-  return true;
+  DCHECK(is_waiting_for_consecutive_frame_);
+  is_waiting_for_consecutive_frame_ = false;
+  EmitAvailableEncodedFrames();
 }
 
-// Called from the main cast thread.
-void VideoReceiver::GetEncodedVideoFrame(
-    const VideoFrameEncodedCallback& callback) {
-  DCHECK(cast_environment_->CurrentlyOn(CastEnvironment::MAIN));
-  scoped_ptr<transport::EncodedVideoFrame> encoded_frame(
-      new transport::EncodedVideoFrame());
-  bool next_frame = false;
+base::TimeTicks VideoReceiver::GetPlayoutTime(base::TimeTicks now,
+                                              uint32 rtp_timestamp) {
+  // TODO(miu): This and AudioReceiver::GetPlayoutTime() need to be reconciled!
 
-  if (!framer_->GetEncodedVideoFrame(encoded_frame.get(), &next_frame)) {
-    // We have no video frames. Wait for new packet(s).
-    queued_encoded_callbacks_.push_back(callback);
-    return;
-  }
-
-  if (decryptor_.initialized() && !DecryptVideoFrame(&encoded_frame)) {
-    // Logging already done.
-    queued_encoded_callbacks_.push_back(callback);
-    return;
-  }
-
-  base::TimeTicks render_time;
-  if (PullEncodedVideoFrame(next_frame, &encoded_frame, &render_time)) {
-    cast_environment_->PostTask(
-        CastEnvironment::MAIN,
-        FROM_HERE,
-        base::Bind(callback, base::Passed(&encoded_frame), render_time));
-  } else {
-    // We have a video frame; however we are missing packets and we have time
-    // to wait for new packet(s).
-    queued_encoded_callbacks_.push_back(callback);
-  }
-}
-
-// Should we pull the encoded video frame from the framer? decided by if this is
-// the next frame or we are running out of time and have to pull the following
-// frame.
-// If the frame is too old to be rendered we set the don't show flag in the
-// video bitstream where possible.
-bool VideoReceiver::PullEncodedVideoFrame(
-    bool next_frame,
-    scoped_ptr<transport::EncodedVideoFrame>* encoded_frame,
-    base::TimeTicks* render_time) {
-  DCHECK(cast_environment_->CurrentlyOn(CastEnvironment::MAIN));
-  base::TimeTicks now = cast_environment_->Clock()->NowTicks();
-  *render_time = GetRenderTime(now, (*encoded_frame)->rtp_timestamp);
-
-  // TODO(mikhal): Store actual render time and not diff.
-  cast_environment_->Logging()->InsertFrameEventWithDelay(
-      now,
-      kVideoRenderDelay,
-      (*encoded_frame)->rtp_timestamp,
-      (*encoded_frame)->frame_id,
-      now - *render_time);
-
-  // Minimum time before a frame is due to be rendered before we pull it for
-  // decode.
-  base::TimeDelta min_wait_delta = frame_delay_;
-  base::TimeDelta time_until_render = *render_time - now;
-  if (!next_frame && (time_until_render > min_wait_delta)) {
-    // Example:
-    // We have decoded frame 1 and we have received the complete frame 3, but
-    // not frame 2. If we still have time before frame 3 should be rendered we
-    // will wait for 2 to arrive, however if 2 never show up this timer will hit
-    // and we will pull out frame 3 for decoding and rendering.
-    base::TimeDelta time_until_release = time_until_render - min_wait_delta;
-    cast_environment_->PostDelayedTask(
-        CastEnvironment::MAIN,
-        FROM_HERE,
-        base::Bind(&VideoReceiver::PlayoutTimeout, weak_factory_.GetWeakPtr()),
-        time_until_release);
-    VLOG(1) << "Wait before releasing frame "
-            << static_cast<int>((*encoded_frame)->frame_id) << " time "
-            << time_until_release.InMilliseconds();
-    return false;
-  }
-
-  base::TimeDelta dont_show_timeout_delta =
-      base::TimeDelta::FromMilliseconds(-kDontShowTimeoutMs);
-  if (codec_ == transport::kVp8 &&
-      time_until_render < dont_show_timeout_delta) {
-    (*encoded_frame)->data[0] &= 0xef;
-    VLOG(1) << "Don't show frame "
-            << static_cast<int>((*encoded_frame)->frame_id)
-            << " time_until_render:" << time_until_render.InMilliseconds();
-  } else {
-    VLOG(2) << "Show frame " << static_cast<int>((*encoded_frame)->frame_id)
-            << " time_until_render:" << time_until_render.InMilliseconds();
-  }
-  // We have a copy of the frame, release this one.
-  framer_->ReleaseFrame((*encoded_frame)->frame_id);
-  (*encoded_frame)->codec = codec_;
-
-  // Used by chrome/browser/extension/api/cast_streaming/performance_test.cc
-  TRACE_EVENT_INSTANT2(
-      "cast_perf_test", "PullEncodedVideoFrame",
-      TRACE_EVENT_SCOPE_THREAD,
-      "rtp_timestamp", (*encoded_frame)->rtp_timestamp,
-      "render_time", render_time->ToInternalValue());
-
-  return true;
-}
-
-void VideoReceiver::PlayoutTimeout() {
-  DCHECK(cast_environment_->CurrentlyOn(CastEnvironment::MAIN));
-  if (queued_encoded_callbacks_.empty())
-    return;
-
-  bool next_frame = false;
-  scoped_ptr<transport::EncodedVideoFrame> encoded_frame(
-      new transport::EncodedVideoFrame());
-
-  if (!framer_->GetEncodedVideoFrame(encoded_frame.get(), &next_frame)) {
-    // We have no video frames. Wait for new packet(s).
-    // Since the application can post multiple VideoFrameEncodedCallback and
-    // we only check the next frame to play out we might have multiple timeout
-    // events firing after each other; however this should be a rare event.
-    VLOG(1) << "Failed to retrieved a complete frame at this point in time";
-    return;
-  }
-  VLOG(2) << "PlayoutTimeout retrieved frame "
-          << static_cast<int>(encoded_frame->frame_id);
-
-  if (decryptor_.initialized() && !DecryptVideoFrame(&encoded_frame)) {
-    // Logging already done.
-    return;
-  }
-
-  base::TimeTicks render_time;
-  if (PullEncodedVideoFrame(next_frame, &encoded_frame, &render_time)) {
-    if (!queued_encoded_callbacks_.empty()) {
-      VideoFrameEncodedCallback callback = queued_encoded_callbacks_.front();
-      queued_encoded_callbacks_.pop_front();
-      cast_environment_->PostTask(
-          CastEnvironment::MAIN,
-          FROM_HERE,
-          base::Bind(callback, base::Passed(&encoded_frame), render_time));
-    }
-  }
-  // Else we have a video frame; however we are missing packets and we have time
-  // to wait for new packet(s).
-}
-
-base::TimeTicks VideoReceiver::GetRenderTime(base::TimeTicks now,
-                                             uint32 rtp_timestamp) {
   DCHECK(cast_environment_->CurrentlyOn(CastEnvironment::MAIN));
   // Senders time in ms when this frame was captured.
   // Note: the senders clock and our local clock might not be synced.
   base::TimeTicks rtp_timestamp_in_ticks;
 
   // Compute the time offset_in_ticks based on the incoming_rtp_timestamp_.
   if (time_offset_counter_ == 0) {
     // Check for received RTCP to sync the stream play it out asap.
-    if (rtcp_->RtpTimestampInSenderTime(kVideoFrequency,
-                                        incoming_rtp_timestamp_,
-                                        &rtp_timestamp_in_ticks)) {
-
+    if (rtcp_.RtpTimestampInSenderTime(kVideoFrequency,
+                                       incoming_rtp_timestamp_,
+                                       &rtp_timestamp_in_ticks)) {
        ++time_offset_counter_;
     }
-    return now;
   } else if (time_incoming_packet_updated_) {
-    if (rtcp_->RtpTimestampInSenderTime(kVideoFrequency,
-                                        incoming_rtp_timestamp_,
-                                        &rtp_timestamp_in_ticks)) {
+    if (rtcp_.RtpTimestampInSenderTime(kVideoFrequency,
+                                       incoming_rtp_timestamp_,
+                                       &rtp_timestamp_in_ticks)) {
       // Time to update the time_offset.
       base::TimeDelta time_offset =
           time_incoming_packet_ - rtp_timestamp_in_ticks;
       // Taking the minimum of the first kTimeOffsetMaxCounter values. We are
       // assuming that we are looking for the minimum offset, which will occur
       // when network conditions are the best. This should occur at least once
       // within the first kTimeOffsetMaxCounter samples. Any drift should be
       // very slow, and negligible for this use case.
       if (time_offset_counter_ == 1)
         time_offset_ = time_offset;
-      else if (time_offset_counter_  < kTimeOffsetMaxCounter) {
+      else if (time_offset_counter_ < kTimeOffsetMaxCounter) {
         time_offset_ = std::min(time_offset_, time_offset);
       }
-      ++time_offset_counter_;
+      if (time_offset_counter_ < kTimeOffsetMaxCounter)
+        ++time_offset_counter_;
     }
   }
   // Reset |time_incoming_packet_updated_| to enable a future measurement.
   time_incoming_packet_updated_ = false;
   // Compute the actual rtp_timestamp_in_ticks based on the current timestamp.
-  if (!rtcp_->RtpTimestampInSenderTime(
+  if (!rtcp_.RtpTimestampInSenderTime(
            kVideoFrequency, rtp_timestamp, &rtp_timestamp_in_ticks)) {
     // This can fail if we have not received any RTCP packets in a long time.
-    return now;
+    // BUG: These calculations are a placeholder, and to be revisited in a
+    // soon-upcoming change.  http://crbug.com/356942
+    const int frequency_khz = kVideoFrequency / 1000;
+    const base::TimeDelta delta_based_on_rtp_timestamps =
+        base::TimeDelta::FromMilliseconds(
+            static_cast<int32>(rtp_timestamp - incoming_rtp_timestamp_) /
+                frequency_khz);
+    return time_incoming_packet_ + delta_based_on_rtp_timestamps;
   }
 
   base::TimeTicks render_time =
       rtp_timestamp_in_ticks + time_offset_ + target_delay_delta_;
+  // TODO(miu): This is broken since this "getter" method may be called on
+  // frames received out-of-order, which means the playout times for earlier
+  // frames will be computed incorrectly.
+#if 0
   if (last_render_time_ > render_time)
     render_time = last_render_time_;
   last_render_time_ = render_time;
+#endif
+
   return render_time;
 }
 
 void VideoReceiver::IncomingPacket(scoped_ptr<Packet> packet) {
   DCHECK(cast_environment_->CurrentlyOn(CastEnvironment::MAIN));
   if (Rtcp::IsRtcpPacket(&packet->front(), packet->size())) {
-    rtcp_->IncomingRtcpPacket(&packet->front(), packet->size());
+    rtcp_.IncomingRtcpPacket(&packet->front(), packet->size());
   } else {
     ReceivedPacket(&packet->front(), packet->size());
   }
 }
 
 void VideoReceiver::OnReceivedPayloadData(const uint8* payload_data,
                                           size_t payload_size,
                                           const RtpCastHeader& rtp_header) {
   DCHECK(cast_environment_->CurrentlyOn(CastEnvironment::MAIN));
 
@@ skipping 18 matching lines @@
   cast_environment_->Logging()->InsertPacketEvent(
       now,
       kVideoPacketReceived,
       rtp_header.webrtc.header.timestamp,
       rtp_header.frame_id,
       rtp_header.packet_id,
       rtp_header.max_packet_id,
       payload_size);
 
   bool duplicate = false;
-  bool complete =
-      framer_->InsertPacket(payload_data, payload_size, rtp_header, &duplicate);
-
+  const bool complete =
+      framer_.InsertPacket(payload_data, payload_size, rtp_header, &duplicate);
   if (duplicate) {
     cast_environment_->Logging()->InsertPacketEvent(
         now,
         kDuplicateVideoPacketReceived,
         rtp_header.webrtc.header.timestamp,
         rtp_header.frame_id,
         rtp_header.packet_id,
         rtp_header.max_packet_id,
         payload_size);
     // Duplicate packets are ignored.
     return;
   }
   if (!complete)
     return;  // Video frame not complete; wait for more packets.
-  if (queued_encoded_callbacks_.empty())
-    return;  // No pending callback.
 
-  VideoFrameEncodedCallback callback = queued_encoded_callbacks_.front();
-  queued_encoded_callbacks_.pop_front();
-  cast_environment_->PostTask(CastEnvironment::MAIN,
-                              FROM_HERE,
-                              base::Bind(&VideoReceiver::GetEncodedVideoFrame,
-                                         weak_factory_.GetWeakPtr(),
-                                         callback));
+  EmitAvailableEncodedFrames();
 }
 
 // Send a cast feedback message. Actual message created in the framer (cast
 // message builder).
 void VideoReceiver::CastFeedback(const RtcpCastMessage& cast_message) {
   DCHECK(cast_environment_->CurrentlyOn(CastEnvironment::MAIN));
 
   base::TimeTicks now = cast_environment_->Clock()->NowTicks();
   RtpTimestamp rtp_timestamp =
       frame_id_to_rtp_timestamp_[cast_message.ack_frame_id_ & 0xff];
   cast_environment_->Logging()->InsertFrameEvent(
       now, kVideoAckSent, rtp_timestamp, cast_message.ack_frame_id_);
 
-  rtcp_->SendRtcpFromRtpReceiver(&cast_message, &event_subscriber_);
+  rtcp_.SendRtcpFromRtpReceiver(&cast_message, &event_subscriber_);
 }
 
 // Cast messages should be sent within a maximum interval. Schedule a call
 // if not triggered elsewhere, e.g. by the cast message_builder.
 void VideoReceiver::ScheduleNextCastMessage() {
   DCHECK(cast_environment_->CurrentlyOn(CastEnvironment::MAIN));
   base::TimeTicks send_time;
-  framer_->TimeToSendNextCastMessage(&send_time);
-
+  framer_.TimeToSendNextCastMessage(&send_time);
   base::TimeDelta time_to_send =
       send_time - cast_environment_->Clock()->NowTicks();
   time_to_send = std::max(
       time_to_send, base::TimeDelta::FromMilliseconds(kMinSchedulingDelayMs));
   cast_environment_->PostDelayedTask(
       CastEnvironment::MAIN,
       FROM_HERE,
       base::Bind(&VideoReceiver::SendNextCastMessage,
                  weak_factory_.GetWeakPtr()),
       time_to_send);
 }
 
 void VideoReceiver::SendNextCastMessage() {
   DCHECK(cast_environment_->CurrentlyOn(CastEnvironment::MAIN));
-  framer_->SendCastMessage();  // Will only send a message if it is time.
+  framer_.SendCastMessage();  // Will only send a message if it is time.
   ScheduleNextCastMessage();
 }
 
-// Schedule the next RTCP report to be sent back to the sender.
 void VideoReceiver::ScheduleNextRtcpReport() {
   DCHECK(cast_environment_->CurrentlyOn(CastEnvironment::MAIN));
-  base::TimeDelta time_to_next = rtcp_->TimeToSendNextRtcpReport() -
+  base::TimeDelta time_to_next = rtcp_.TimeToSendNextRtcpReport() -
                                  cast_environment_->Clock()->NowTicks();
 
   time_to_next = std::max(
       time_to_next, base::TimeDelta::FromMilliseconds(kMinSchedulingDelayMs));
 
   cast_environment_->PostDelayedTask(
       CastEnvironment::MAIN,
       FROM_HERE,
       base::Bind(&VideoReceiver::SendNextRtcpReport,
                  weak_factory_.GetWeakPtr()),
       time_to_next);
 }
 
 void VideoReceiver::SendNextRtcpReport() {
   DCHECK(cast_environment_->CurrentlyOn(CastEnvironment::MAIN));
-  rtcp_->SendRtcpFromRtpReceiver(NULL, NULL);
+  rtcp_.SendRtcpFromRtpReceiver(NULL, NULL);
   ScheduleNextRtcpReport();
 }
 
-void VideoReceiver::UpdateTargetDelay() {
-  NOTIMPLEMENTED();
-  rtcp_->SetTargetDelay(target_delay_delta_);
-  target_delay_cb_.Run(target_delay_delta_);
-}
-
 }  // namespace cast
 }  // namespace media