More gracefully handle rtp timestamp jumps in the rtp to ntp estimator.

webrtc/system_wrappers/source/rtp_to_ntp_estimator.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 36 matching lines @@
 }
 
 bool Contains(const std::list<RtpToNtpEstimator::RtcpMeasurement>& measurements,
               const RtpToNtpEstimator::RtcpMeasurement& other) {
   for (const auto& measurement : measurements) {
     if (measurement.IsEqual(other))
       return true;
   }
   return false;
 }
-
-bool IsValid(const std::list<RtpToNtpEstimator::RtcpMeasurement>& measurements,
-             const RtpToNtpEstimator::RtcpMeasurement& other) {
-  if (!other.ntp_time.Valid())
-    return false;
-
-  int64_t ntp_ms_new = other.ntp_time.ToMs();
-  for (const auto& measurement : measurements) {
-    if (ntp_ms_new <= measurement.ntp_time.ToMs()) {
-      // Old report.
-      return false;
-    }
-    int64_t timestamp_new = other.rtp_timestamp;
-    if (!CompensateForWrapAround(timestamp_new, measurement.rtp_timestamp,
-                                 &timestamp_new)) {
-      return false;
-    }
-    if (timestamp_new <= measurement.rtp_timestamp) {
-      LOG(LS_WARNING) << "Newer RTCP SR report with older RTP timestamp.";
-      return false;
-    }
-  }
-  return true;
-}
 }  // namespace
 
 RtpToNtpEstimator::RtcpMeasurement::RtcpMeasurement(uint32_t ntp_secs,
                                                     uint32_t ntp_frac,
                                                     uint32_t timestamp)
     : ntp_time(ntp_secs, ntp_frac), rtp_timestamp(timestamp) {}
 
 bool RtpToNtpEstimator::RtcpMeasurement::IsEqual(
     const RtcpMeasurement& other) const {
   // Use || since two equal timestamps will result in zero frequency and in
   // RtpToNtpMs, |rtp_timestamp_ms| is estimated by dividing by the frequency.
   return (ntp_time == other.ntp_time) || (rtp_timestamp == other.rtp_timestamp);
 }
 
 // Class for converting an RTP timestamp to the NTP domain.
-RtpToNtpEstimator::RtpToNtpEstimator() {}
+RtpToNtpEstimator::RtpToNtpEstimator() : consecutive_invalid_samples_(0) {}
 RtpToNtpEstimator::~RtpToNtpEstimator() {}
 
 void RtpToNtpEstimator::UpdateParameters() {
   if (measurements_.size() != kNumRtcpReportsToUse)
     return;
 
   int64_t timestamp_new = measurements_.front().rtp_timestamp;
   int64_t timestamp_old = measurements_.back().rtp_timestamp;
   if (!CompensateForWrapAround(timestamp_new, timestamp_old, &timestamp_new))
     return;
 
   int64_t ntp_ms_new = measurements_.front().ntp_time.ToMs();
   int64_t ntp_ms_old = measurements_.back().ntp_time.ToMs();
 
   if (!CalculateFrequency(ntp_ms_new, timestamp_new, ntp_ms_old, timestamp_old,
                           &params_.frequency_khz)) {
     return;
   }
   params_.offset_ms = timestamp_new - params_.frequency_khz * ntp_ms_new;
   params_.calculated = true;
 }
 
 bool RtpToNtpEstimator::UpdateMeasurements(uint32_t ntp_secs,
                                            uint32_t ntp_frac,
                                            uint32_t rtp_timestamp,
                                            bool* new_rtcp_sr) {
   *new_rtcp_sr = false;
 
-  RtcpMeasurement measurement(ntp_secs, ntp_frac, rtp_timestamp);
-  if (Contains(measurements_, measurement)) {
+  RtcpMeasurement new_measurement(ntp_secs, ntp_frac, rtp_timestamp);
+  if (Contains(measurements_, new_measurement)) {
     // RTCP SR report already added.
     return true;
   }
-  if (!IsValid(measurements_, measurement)) {
-    // Old report or invalid parameters.
+  if (!new_measurement.ntp_time.Valid())
     return false;
+
+  int64_t ntp_ms_new = new_measurement.ntp_time.ToMs();
+  bool invalid_sample = false;
+  for (const auto& measurement : measurements_) {
+    if (ntp_ms_new <= measurement.ntp_time.ToMs()) {
+      // Old report.
+      invalid_sample = true;
+      break;
+    }
+    int64_t timestamp_new = new_measurement.rtp_timestamp;
+    if (!CompensateForWrapAround(timestamp_new, measurement.rtp_timestamp,
+                                 &timestamp_new)) {
+      invalid_sample = true;
+      break;
+    }
+    if (timestamp_new <= measurement.rtp_timestamp) {
+      LOG(LS_WARNING)
+          << "Newer RTCP SR report with older RTP timestamp, dropping";
+      invalid_sample = true;
+      break;
+    }
   }
+  if (invalid_sample) {
+    ++consecutive_invalid_samples_;
+    if (consecutive_invalid_samples_ < kMaxInvalidSamples) {
+      return false;
+    }
+    LOG(LS_WARNING) << "Multiple consecutively invalid RTCP SR reports, "
+                       "clearing measurements.";
+    measurements_.clear();
+  }
+  consecutive_invalid_samples_ = 0;
 
   // Insert new RTCP SR report.
   if (measurements_.size() == kNumRtcpReportsToUse)
     measurements_.pop_back();
 
-  measurements_.push_front(measurement);
+  measurements_.push_front(new_measurement);
   *new_rtcp_sr = true;
 
   // List updated, calculate new parameters.
   UpdateParameters();
   return true;
 }
 
 bool RtpToNtpEstimator::Estimate(int64_t rtp_timestamp,
                                  int64_t* rtp_timestamp_ms) const {
   if (!params_.calculated || measurements_.empty())
@@ skipping 29 matching lines @@
     }
   } else if (static_cast<int32_t>(old_timestamp - new_timestamp) > 0) {
     // This difference should be less than -2^31 if we have had a backward wrap
     // around. Since it is cast to a int32_t, it should be positive.
     return -1;
   }
   return 0;
 }
 
 }  // namespace webrtc