Improve probing by ignoring small packets which otherwise break the mechanism.

webrtc/modules/pacing/bitrate_prober.cc

 /*
  *  Copyright (c) 2014 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 11 matching lines @@
 namespace {
 int ComputeDeltaFromBitrate(size_t packet_size, int bitrate_bps) {
   assert(bitrate_bps > 0);
   // Compute the time delta needed to send packet_size bytes at bitrate_bps
   // bps. Result is in milliseconds.
   return static_cast<int>(1000ll * static_cast<int64_t>(packet_size) * 8ll /
       bitrate_bps);
 }
 }  // namespace
 
+const size_t BitrateProber::kMinProbePacketSize = 200;
+
 BitrateProber::BitrateProber()
     : probing_state_(kDisabled),
       packet_size_last_send_(0),
       time_last_send_ms_(-1) {
 }
 
 void BitrateProber::SetEnabled(bool enable) {
   if (enable) {
     if (probing_state_ == kDisabled) {
       probing_state_ = kAllowedToProbe;
@@ skipping 39 matching lines @@
     probing_state_ = kWait;
   }
   if (probe_bitrates_.empty()) {
     // No probe started, or waiting for next probe.
     return -1;
   }
   int64_t elapsed_time_ms = now_ms - time_last_send_ms_;
   // We will send the first probe packet immediately if no packet has been
   // sent before.
   int time_until_probe_ms = 0;
-  if (packet_size_last_send_ > 0 && probing_state_ == kProbing) {
+  if (packet_size_last_send_ > kMinProbePacketSize &&
+      probing_state_ == kProbing) {
     int next_delta_ms = ComputeDeltaFromBitrate(packet_size_last_send_,
                                                 probe_bitrates_.front());
     time_until_probe_ms = next_delta_ms - elapsed_time_ms;
     // There is no point in trying to probe with less than 1 ms between packets
     // as it essentially means trying to probe at infinite bandwidth.
     const int kMinProbeDeltaMs = 1;
     // If we have waited more than 3 ms for a new packet to probe with we will
     // consider this probing session over.
     const int kMaxProbeDelayMs = 3;
     if (next_delta_ms < kMinProbeDeltaMs ||
@@ skipping 16 matching lines @@
 void BitrateProber::PacketSent(int64_t now_ms, size_t packet_size) {
   assert(packet_size > 0);
   packet_size_last_send_ = packet_size;
   time_last_send_ms_ = now_ms;
   if (probing_state_ != kProbing)
     return;
   if (!probe_bitrates_.empty())
     probe_bitrates_.pop_front();
 }
 }  // namespace webrtc