Add interval estimator to remote bitrate estimator

webrtc/modules/remote_bitrate_estimator/aimd_rate_control.cc

Index: webrtc/modules/remote_bitrate_estimator/aimd_rate_control.cc
diff --git a/webrtc/modules/remote_bitrate_estimator/aimd_rate_control.cc b/webrtc/modules/remote_bitrate_estimator/aimd_rate_control.cc
index f83cddc617862b56ca50131895e97921084178b2..38a31be4eed647179328a7994c8aad839595feae 100644
--- a/webrtc/modules/remote_bitrate_estimator/aimd_rate_control.cc
+++ b/webrtc/modules/remote_bitrate_estimator/aimd_rate_control.cc
@@ -130,6 +130,14 @@ void AimdRateControl::SetEstimate(int bitrate_bps, int64_t now_ms) {
   current_bitrate_bps_ = ChangeBitrate(bitrate_bps, bitrate_bps, now_ms);
 }
 
+rtc::Optional<int> AimdRateControl::GetNearMaxIncreaseRate() const {
+  return near_max_increase_rate_bps_;
+}
+
+rtc::Optional<int> AimdRateControl::GetLastDecrease() const {
+  return last_decrease_;
+}
+
 uint32_t AimdRateControl::ChangeBitrate(uint32_t current_bitrate_bps,
                                         uint32_t incoming_bitrate_bps,
                                         int64_t now_ms) {
@@ -165,9 +173,15 @@ uint32_t AimdRateControl::ChangeBitrate(uint32_t current_bitrate_bps,
         const int64_t response_time = rtt_ + 100;
         uint32_t additive_increase_bps = AdditiveRateIncrease(
             now_ms, time_last_bitrate_change_, response_time);
+        if (last_near_max_increase_rate_update_) {
+          near_max_increase_rate_bps_ = rtc::Optional<int>(
+              additive_increase_bps * 1000.0 /
+              (now_ms - *last_near_max_increase_rate_update_));

[stefan-webrtc, 2016/10/26 14:30:06]

An alternative to this would be to do something like:
std::min(now_ms - time_last_bitrate_change_, 500) or something like that. WDYT?

[michaelt, 2016/10/31 11:10:22]

I taught a little what would be the best solution. I would prefer to have a
"NearMaxIncresaseRate" function which would calculate the actual increase rate
depending on rtt,bitrate,.... This function would be then used in
AdditiveRateIncrease and for the probing interval estimator. We would have to
remove the min_increse per call, but we could replace it with a
min_increase_rate. WDYT?

+        }
         current_bitrate_bps += additive_increase_bps;
-
+        last_near_max_increase_rate_update_ = rtc::Optional<int64_t>(now_ms);
       } else {
+        last_near_max_increase_rate_update_ = rtc::Optional<int64_t>();
         uint32_t multiplicative_increase_bps = MultiplicativeRateIncrease(
             now_ms, time_last_bitrate_change_, current_bitrate_bps);
         current_bitrate_bps += multiplicative_increase_bps;
@@ -177,6 +191,7 @@ uint32_t AimdRateControl::ChangeBitrate(uint32_t current_bitrate_bps,
       break;
 
     case kRcDecrease:
+      last_near_max_increase_rate_update_ = rtc::Optional<int64_t>();
       bitrate_is_initialized_ = true;
       if (incoming_bitrate_bps < min_configured_bitrate_bps_) {
         current_bitrate_bps = min_configured_bitrate_bps_;
@@ -196,6 +211,9 @@ uint32_t AimdRateControl::ChangeBitrate(uint32_t current_bitrate_bps,
         }
         ChangeRegion(kRcNearMax);
 
+        if (incoming_bitrate_bps < current_bitrate_bps_)
+          last_decrease_ =
+              rtc::Optional<int>(current_bitrate_bps_ - current_bitrate_bps);
         if (incoming_bitrate_kbps < avg_max_bitrate_kbps_ -
             3 * std_max_bit_rate) {
           avg_max_bitrate_kbps_ = -1.0f;