Change TWCC send interval to reduce overhead on low BW situations.

webrtc/modules/remote_bitrate_estimator/remote_estimator_proxy.h

Index: webrtc/modules/remote_bitrate_estimator/remote_estimator_proxy.h
diff --git a/webrtc/modules/remote_bitrate_estimator/remote_estimator_proxy.h b/webrtc/modules/remote_bitrate_estimator/remote_estimator_proxy.h
index 127886300d8f95c2fd14d78ebc0ffae9ee5c1094..81a1051cb4c27083ff2ca8372fe77d34ca8c4c90 100644
--- a/webrtc/modules/remote_bitrate_estimator/remote_estimator_proxy.h
+++ b/webrtc/modules/remote_bitrate_estimator/remote_estimator_proxy.h
@@ -12,14 +12,17 @@
 #define WEBRTC_MODULES_REMOTE_BITRATE_ESTIMATOR_REMOTE_ESTIMATOR_PROXY_H_
 
 #include <map>
+#include <memory>
 #include <vector>
 
 #include "webrtc/base/criticalsection.h"
+#include "webrtc/base/ratetracker.h"
 #include "webrtc/modules/include/module_common_types.h"
 #include "webrtc/modules/remote_bitrate_estimator/include/remote_bitrate_estimator.h"
 
 namespace webrtc {
 
+class BitrateController;
 class Clock;
 class PacketRouter;
 namespace rtcp {
@@ -32,7 +35,9 @@ class TransportFeedback;
 
 class RemoteEstimatorProxy : public RemoteBitrateEstimator {
  public:
-  RemoteEstimatorProxy(Clock* clock, PacketRouter* packet_router);
+  RemoteEstimatorProxy(Clock* clock,
+                       PacketRouter* packet_router,
+                       BitrateController* bitrate_controller);

[stefan-webrtc, 2016/10/26 14:45:16]

I'm not sure I like this dependency... We can't know if the receiver is also a
sender, and if it's a pure receiver it won't have a valid bandwidth estimate on
its uplink. In that case I think it's better to base this on the bitrate
received?

[michaelt, 2016/10/27 15:15:44]

But if we use bitrate received we assume that we are in a symmetrical network
witch is not necessary the case.

[stefan-webrtc, 2016/10/31 08:54:36]

Right, when the client is receive-only we have to decide on something. Either we
base it on the receive bitrate or we hard code it. WDYT?

If we want the RemoteEstimatorProxy to have access to the send bandwidth I think
I'd prefer to do it through an observer interface, for instance BitrateObserver
(see webrtc/modules/bitrate_controller/include/bitrate_controller.h).

[michaelt, 2016/10/31 13:03:15]

For this CL i would use a hard coded rate on the receive-only case.

I discover some problems on using BitrateObserver.
1. BitrateObserver seams to be deprecated.
2. It seams that in the current impl. there is no way to inform multiple
BitrateObserver.

What do you think about set the current send bandwidth in RemoteEstimatorProxy
with a function "OnBitrateChanged" called in the function
"MaybeTriggerOnNetworkChanged" in the CongestionController ?   

[stefan-webrtc, 2016/10/31 14:04:19]

Constant rate for receive only and using OnBitrateChanged() both sound good to
me. 

[michaelt, 2016/11/02 10:10:06]

Done.

   virtual ~RemoteEstimatorProxy();
 
   void IncomingPacketFeedbackVector(
@@ -48,7 +53,9 @@ class RemoteEstimatorProxy : public RemoteBitrateEstimator {
   int64_t TimeUntilNextProcess() override;
   void Process() override;
 
-  static const int kDefaultProcessIntervalMs;
+  static const int kMinSendIntervalMs;
+  static const int kMaxSendIntervalMs;
+  static const int kMinPacketCountRecievedBitrate;

[stefan-webrtc, 2016/10/26 14:45:16]

Received

[michaelt, 2016/10/27 15:15:44]

Removed this const since its not used anymore. 

   static const int kBackWindowMs;
 
  private:
@@ -68,6 +75,7 @@ class RemoteEstimatorProxy : public RemoteBitrateEstimator {
   int64_t window_start_seq_ GUARDED_BY(&lock_);
   // Map unwrapped seq -> time.
   std::map<int64_t, int64_t> packet_arrival_times_ GUARDED_BY(&lock_);
+  BitrateController* bitrate_controller_;
 };
 
 }  // namespace webrtc