Update RateStatistics to handle too-little-data case.

webrtc/modules/remote_bitrate_estimator/remote_bitrate_estimator_single_stream.cc

 /*
  *  Copyright (c) 2012 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 26 matching lines @@
                       kTimestampToMs,
                       enable_burst_grouping),
         estimator(options),
         detector(options) {}
   int64_t last_packet_time_ms;
   InterArrival inter_arrival;
   OveruseEstimator estimator;
   OveruseDetector detector;
 };
 
-  RemoteBitrateEstimatorSingleStream::RemoteBitrateEstimatorSingleStream(
-      RemoteBitrateObserver* observer,
-      Clock* clock)
-      : clock_(clock),
-        incoming_bitrate_(kBitrateWindowMs, 8000),
-        remote_rate_(new AimdRateControl()),
-        observer_(observer),
-        crit_sect_(CriticalSectionWrapper::CreateCriticalSection()),
-        last_process_time_(-1),
-        process_interval_ms_(kProcessIntervalMs) {
+RemoteBitrateEstimatorSingleStream::RemoteBitrateEstimatorSingleStream(
+    RemoteBitrateObserver* observer,
+    Clock* clock)
+    : clock_(clock),
+      incoming_bitrate_(kBitrateWindowMs, 8000),
+      last_valid_incoming_bitrate_(0),
+      remote_rate_(new AimdRateControl()),
+      observer_(observer),
+      crit_sect_(CriticalSectionWrapper::CreateCriticalSection()),
+      last_process_time_(-1),
+      process_interval_ms_(kProcessIntervalMs) {
   assert(observer_);
   LOG(LS_INFO) << "RemoteBitrateEstimatorSingleStream: Instantiating.";
 }
 
 RemoteBitrateEstimatorSingleStream::~RemoteBitrateEstimatorSingleStream() {
   while (!overuse_detectors_.empty()) {
     SsrcOveruseEstimatorMap::iterator it = overuse_detectors_.begin();
     delete it->second;
     overuse_detectors_.erase(it);
   }
@@ skipping 16 matching lines @@
     // callback will no longer be called for the old SSRC. This will be
     // automatically cleaned up when we have one RemoteBitrateEstimator per REMB
     // group.
     std::pair<SsrcOveruseEstimatorMap::iterator, bool> insert_result =
         overuse_detectors_.insert(std::make_pair(
             ssrc, new Detector(now_ms, OverUseDetectorOptions(), true)));
     it = insert_result.first;
   }
   Detector* estimator = it->second;
   estimator->last_packet_time_ms = now_ms;
+
+  // Check if incoming bitrate estimate is valid, and if it needs to be reset.
+  rtc::Optional<uint32_t> incoming_bitrate = incoming_bitrate_.Rate(now_ms);
+  if (incoming_bitrate) {
+    last_valid_incoming_bitrate_ = *incoming_bitrate;
+  } else if (last_valid_incoming_bitrate_ > 0) {
+    // Incoming bitrate had a previous valid value, but now not enough data
+    // point are left within the current window. Reset incoming bitrate
+    // estimator so that the window size will only contain new data points.
+    incoming_bitrate_.Reset();
+    last_valid_incoming_bitrate_ = 0;
+  }
   incoming_bitrate_.Update(payload_size, now_ms);
+
   const BandwidthUsage prior_state = estimator->detector.State();
   uint32_t timestamp_delta = 0;
   int64_t time_delta = 0;
   int size_delta = 0;
   if (estimator->inter_arrival.ComputeDeltas(rtp_timestamp, arrival_time_ms,
                                              payload_size, &timestamp_delta,
                                              &time_delta, &size_delta)) {
     double timestamp_delta_ms = timestamp_delta * kTimestampToMs;
     estimator->estimator.Update(time_delta, timestamp_delta_ms, size_delta,
                                 estimator->detector.State());
     estimator->detector.Detect(estimator->estimator.offset(),
                                timestamp_delta_ms,
                                estimator->estimator.num_of_deltas(), now_ms);
   }
   if (estimator->detector.State() == kBwOverusing) {
-    uint32_t incoming_bitrate_bps = incoming_bitrate_.Rate(now_ms);
-    if (prior_state != kBwOverusing ||
-        remote_rate_->TimeToReduceFurther(now_ms, incoming_bitrate_bps)) {
+    rtc::Optional<uint32_t> incoming_bitrate_bps =
+        incoming_bitrate_.Rate(now_ms);
+    if (incoming_bitrate_bps &&
+        (prior_state != kBwOverusing ||
+         remote_rate_->TimeToReduceFurther(now_ms, *incoming_bitrate_bps))) {
       // The first overuse should immediately trigger a new estimate.
       // We also have to update the estimate immediately if we are overusing
       // and the target bitrate is too high compared to what we are receiving.
       UpdateEstimate(now_ms);
     }
   }
 }
 
 void RemoteBitrateEstimatorSingleStream::Process() {
   if (TimeUntilNextProcess() > 0) {
@@ skipping 38 matching lines @@
         bw_state = it->second->detector.State();
       }
       ++it;
     }
   }
   // We can't update the estimate if we don't have any active streams.
   if (overuse_detectors_.empty()) {
     remote_rate_.reset(new AimdRateControl());
     return;
   }
+
   double mean_noise_var = sum_var_noise /
       static_cast<double>(overuse_detectors_.size());
   const RateControlInput input(bw_state,
                                incoming_bitrate_.Rate(now_ms),
                                mean_noise_var);
   remote_rate_->Update(&input, now_ms);
   uint32_t target_bitrate = remote_rate_->UpdateBandwidthEstimate(now_ms);
   if (remote_rate_->ValidEstimate()) {
     process_interval_ms_ = remote_rate_->GetFeedbackInterval();
     std::vector<uint32_t> ssrcs;
@@ skipping 43 matching lines @@
     (*ssrcs)[i] = it->first;
   }
 }
 
 void RemoteBitrateEstimatorSingleStream::SetMinBitrate(int min_bitrate_bps) {
   CriticalSectionScoped cs(crit_sect_.get());
   remote_rate_->SetMinBitrate(min_bitrate_bps);
 }
 
 }  // namespace webrtc