[Cast] Aggressively send sender reports until first receiver report is received.

media/cast/video_sender/video_sender.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_sender/video_sender.h"
 
 #include <cstring>
 #include <list>
 
 #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/rtcp/rtcp_defines.h"
 #include "media/cast/transport/cast_transport_config.h"
 #include "media/cast/video_sender/external_video_encoder.h"
 #include "media/cast/video_sender/video_encoder_impl.h"
 
 namespace media {
 namespace cast {
 
-const int64 kMinSchedulingDelayMs = 1;
-
-class LocalRtcpVideoSenderFeedback : public RtcpSenderFeedback {
- public:
-  explicit LocalRtcpVideoSenderFeedback(VideoSender* video_sender)
-      : video_sender_(video_sender) {}
-
-  virtual void OnReceivedCastFeedback(const RtcpCastMessage& cast_feedback)
-      OVERRIDE {
-    video_sender_->OnReceivedCastFeedback(cast_feedback);
-  }
-
- private:
-  VideoSender* video_sender_;
-
-  DISALLOW_IMPLICIT_CONSTRUCTORS(LocalRtcpVideoSenderFeedback);
-};
+const int kNumAggressiveReportsSentAtStart = 100;
+const int kMinSchedulingDelayMs = 1;
 
 VideoSender::VideoSender(
     scoped_refptr<CastEnvironment> cast_environment,
     const VideoSenderConfig& video_config,
     const CreateVideoEncodeAcceleratorCallback& create_vea_cb,
     const CreateVideoEncodeMemoryCallback& create_video_encode_mem_cb,
     const CastInitializationCallback& cast_initialization_cb,
     transport::CastTransportSender* const transport_sender)
     : rtp_max_delay_(base::TimeDelta::FromMilliseconds(
           video_config.rtp_config.max_delay_ms)),
       max_frame_rate_(video_config.max_frame_rate),
       cast_environment_(cast_environment),
       transport_sender_(transport_sender),
       rtp_timestamp_helper_(kVideoFrequency),
-      rtcp_feedback_(new LocalRtcpVideoSenderFeedback(this)),
+      num_aggressive_rtcp_reports_sent_(0),
       last_acked_frame_id_(-1),
       last_sent_frame_id_(-1),
       frames_in_encoder_(0),
       duplicate_ack_(0),
       last_skip_count_(0),
       current_requested_bitrate_(video_config.start_bitrate),
       congestion_control_(cast_environment->Clock(),
                           video_config.congestion_control_back_off,
                           video_config.max_bitrate,
                           video_config.min_bitrate,
@@ skipping 19 matching lines @@
 
 
   media::cast::transport::CastTransportVideoConfig transport_config;
   transport_config.codec = video_config.codec;
   transport_config.rtp.config = video_config.rtp_config;
   transport_config.rtp.max_outstanding_frames = max_unacked_frames_ + 1;
   transport_sender_->InitializeVideo(transport_config);
 
   rtcp_.reset(
       new Rtcp(cast_environment_,
-               rtcp_feedback_.get(),
+               this,
                transport_sender_,
                NULL,  // paced sender.
                NULL,
                video_config.rtcp_mode,
                base::TimeDelta::FromMilliseconds(video_config.rtcp_interval),
                video_config.rtp_config.ssrc,
                video_config.incoming_feedback_ssrc,
                video_config.rtcp_c_name,
                false));
   rtcp_->SetCastReceiverEventHistorySize(kReceiverRtcpEventHistorySize);
@@ skipping 77 matching lines @@
       TRACE_EVENT_SCOPE_THREAD,
       "rtp_timestamp", encoded_frame->rtp_timestamp);
 
   // Only use lowest 8 bits as key.
   frame_id_to_rtp_timestamp_[frame_id & 0xff] = encoded_frame->rtp_timestamp;
 
   last_sent_frame_id_ = static_cast<int>(encoded_frame->frame_id);
   DCHECK(!encoded_frame->reference_time.is_null());
   rtp_timestamp_helper_.StoreLatestTime(encoded_frame->reference_time,
                                         encoded_frame->rtp_timestamp);
+
+  // At the start of the session, it's important to send reports before each
+  // frame so that the receiver can properly compute playout times.  The reason
+  // more than one report is sent is because transmission is not guaranteed,
+  // only best effort, so send enough that one should almost certainly get
+  // through.
+  if (num_aggressive_rtcp_reports_sent_ < kNumAggressiveReportsSentAtStart) {
+    // SendRtcpReport() will schedule future reports to be made if this is the
+    // last "aggressive report."
+    ++num_aggressive_rtcp_reports_sent_;
+    const bool is_last_aggressive_report =
+        (num_aggressive_rtcp_reports_sent_ == kNumAggressiveReportsSentAtStart);
+    VLOG_IF(1, is_last_aggressive_report) << "Sending last aggressive report.";
+    SendRtcpReport(is_last_aggressive_report);
+  }
+
   transport_sender_->InsertCodedVideoFrame(*encoded_frame);
   UpdateFramesInFlight();
   InitializeTimers();
 }
 
 void VideoSender::IncomingRtcpPacket(scoped_ptr<Packet> packet) {
   DCHECK(cast_environment_->CurrentlyOn(CastEnvironment::MAIN));
   rtcp_->IncomingRtcpPacket(&packet->front(), packet->size());
 }
 
 void VideoSender::ScheduleNextRtcpReport() {
   DCHECK(cast_environment_->CurrentlyOn(CastEnvironment::MAIN));
   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(&VideoSender::SendRtcpReport, weak_factory_.GetWeakPtr()),
+      base::Bind(&VideoSender::SendRtcpReport,
+                 weak_factory_.GetWeakPtr(),
+                 true),
       time_to_next);
 }
 
-void VideoSender::SendRtcpReport() {
+void VideoSender::SendRtcpReport(bool schedule_future_reports) {
   DCHECK(cast_environment_->CurrentlyOn(CastEnvironment::MAIN));
   const base::TimeTicks now = cast_environment_->Clock()->NowTicks();
   uint32 now_as_rtp_timestamp = 0;
   if (rtp_timestamp_helper_.GetCurrentTimeAsRtpTimestamp(
           now, &now_as_rtp_timestamp)) {
     rtcp_->SendRtcpFromRtpSender(now, now_as_rtp_timestamp);
+  } else {
+    // |rtp_timestamp_helper_| should have stored a mapping by this point.
+    NOTREACHED();
   }
-  ScheduleNextRtcpReport();
+  if (schedule_future_reports)
+    ScheduleNextRtcpReport();
 }
 
 void VideoSender::ScheduleNextResendCheck() {
   DCHECK(cast_environment_->CurrentlyOn(CastEnvironment::MAIN));
   base::TimeDelta time_to_next;
   if (last_send_time_.is_null()) {
     time_to_next = rtp_max_delay_;
   } else {
     time_to_next = last_send_time_ - cast_environment_->Clock()->NowTicks() +
                    rtp_max_delay_;
@@ skipping 70 matching lines @@
 void VideoSender::OnReceivedCastFeedback(const RtcpCastMessage& cast_feedback) {
   DCHECK(cast_environment_->CurrentlyOn(CastEnvironment::MAIN));
   base::TimeDelta rtt;
   base::TimeDelta avg_rtt;
   base::TimeDelta min_rtt;
   base::TimeDelta max_rtt;
 
   if (rtcp_->Rtt(&rtt, &avg_rtt, &min_rtt, &max_rtt)) {
     // Don't use a RTT lower than our average.
     rtt = std::max(rtt, avg_rtt);
+
+    // Having the RTT values implies the receiver sent back a receiver report
+    // based on it having received a report from here.  Therefore, ensure this
+    // sender stops aggressively sending reports.
+    if (num_aggressive_rtcp_reports_sent_ < kNumAggressiveReportsSentAtStart) {
+      VLOG(1) << "No longer a need to send reports aggressively (sent "
+              << num_aggressive_rtcp_reports_sent_ << ").";
+      num_aggressive_rtcp_reports_sent_ = kNumAggressiveReportsSentAtStart;
+      ScheduleNextRtcpReport();
+    }
   } else {
     // We have no measured value use default.
     rtt = base::TimeDelta::FromMilliseconds(kStartRttMs);
   }
   if (cast_feedback.missing_frames_and_packets_.empty()) {
     // No lost packets.
     int resend_frame = -1;
     if (last_sent_frame_id_ == -1)
       return;
 
@@ skipping 35 matching lines @@
   ReceivedAck(cast_feedback.ack_frame_id_);
 }
 
 void VideoSender::ReceivedAck(uint32 acked_frame_id) {
   DCHECK(cast_environment_->CurrentlyOn(CastEnvironment::MAIN));
   if (acked_frame_id == UINT32_C(0xFFFFFFFF)) {
     // Receiver is sending a status message before any frames are ready to
     // be acked. Ignore.
     return;
   }
-  // Start sending RTCP packets only after receiving the first ACK, i.e. only
-  // after establishing that the receiver is active.
-  if (last_acked_frame_id_ == -1) {
-    ScheduleNextRtcpReport();
-  }
   last_acked_frame_id_ = static_cast<int>(acked_frame_id);
   base::TimeTicks now = cast_environment_->Clock()->NowTicks();
 
   RtpTimestamp rtp_timestamp =
       frame_id_to_rtp_timestamp_[acked_frame_id & 0xff];
   cast_environment_->Logging()->InsertFrameEvent(
       now, FRAME_ACK_RECEIVED, VIDEO_EVENT, rtp_timestamp, acked_frame_id);
 
   VLOG(2) << "ReceivedAck:" << static_cast<int>(acked_frame_id);
   active_session_ = true;
@@ skipping 37 matching lines @@
 
 void VideoSender::UpdateBitrate(int new_bitrate) {
   // Make sure we don't set the bitrate too insanely low.
   DCHECK_GT(new_bitrate, 1000);
   video_encoder_->SetBitRate(new_bitrate);
   current_requested_bitrate_ = new_bitrate;
 }
 
 }  // namespace cast
 }  // namespace media