BitrateProber: Support higher probing bitrates

webrtc/modules/pacing/bitrate_prober.h

 /*
  *  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 18 matching lines @@
   // Returns true if the prober is in a probing session, i.e., it currently
   // wants packets to be sent out according to the time returned by
   // TimeUntilNextProbe().
   bool IsProbing() const;
 
   // Initializes a new probing session if the prober is allowed to probe. Does
   // not initialize the prober unless the packet size is large enough to probe
   // with.
   void OnIncomingPacket(size_t packet_size);
 
-  // Create a cluster used to probe for |bitrate_bps| with |num_packets| number
-  // of packets.
-  void CreateProbeCluster(int bitrate_bps, int num_packets);
+  // Create a cluster used to probe for |bitrate_bps| with |num_probes| number
+  // of probes.
+  void CreateProbeCluster(int bitrate_bps, int num_probes);

[philipel, 2016/09/21 09:26:39]

Not for this CL, but I think it would be nice if we didn't have to specify how
many probes we want to send, and instead let the BitrateProber determine how
many bytes it needs to send in order to accurately probe for the given bitrate.

 
-  // Returns the number of milliseconds until the next packet should be sent to
+  // Returns the number of milliseconds until the next probe should be sent to
   // get accurate probing.
   int TimeUntilNextProbe(int64_t now_ms);
 
   // Which cluster that is currently being used for probing.
   int CurrentClusterId() const;
 
-  // Returns the number of bytes that the prober recommends for the next probe
-  // packet.
-  size_t RecommendedPacketSize() const;
+  // Returns the minimum number of bytes that the prober recommends for
+  // the next probe.
+  size_t RecommendedMinProbeSize() const;
 
-  // Called to report to the prober that a packet has been sent, which helps the
-  // prober know when to move to the next packet in a probe.
-  void PacketSent(int64_t now_ms, size_t packet_size);
+  // Called to report to the prober that a probe has been sent. In case of
+  // multiple packets per probe, this call would be made at the end of sending
+  // the last packet in probe. |probe_size| is the total size of all packets
+  // in probe.
+  void ProbeSent(int64_t now_ms, size_t probe_size);
 
  private:
   enum class ProbingState {
     // Probing will not be triggered in this state at all times.
     kDisabled,
     // Probing is enabled and ready to trigger on the first packet arrival.
     kInactive,
     // Probe cluster is filled with the set of data rates to be probed and
     // probes are being sent.
     kActive,
     // Probing is enabled, but currently suspended until an explicit trigger
     // to start probing again.
     kSuspended,
   };
 
+  // A probe cluster consists of a set of probes. Each probe in turn can be
+  // divided into a number of packets to accomodate the MTU on the network.
   struct ProbeCluster {
-    int max_probe_packets = 0;
-    int sent_probe_packets = 0;
+    int max_probes = 0;
+    int sent_probes = 0;
     int probe_bitrate_bps = 0;
     int id = -1;
   };
 
   // Resets the state of the prober and clears any cluster/timing data tracked.
   void ResetState();
 
   ProbingState probing_state_;
   // Probe bitrate per packet. These are used to compute the delta relative to
   // the previous probe packet based on the size and time when that packet was
   // sent.
   std::queue<ProbeCluster> clusters_;
-  size_t packet_size_last_sent_;
+  // A probe can include one or more packets.
+  size_t probe_size_last_sent_;
   // The last time a probe was sent.
   int64_t time_last_probe_sent_ms_;
   int next_cluster_id_;
 };
 }  // namespace webrtc
 #endif  // WEBRTC_MODULES_PACING_BITRATE_PROBER_H_