Avoid rescheduling the next RTCP packet if the RTCP sender status doesn't change.

webrtc/modules/rtp_rtcp/source/rtcp_sender.cc

Index: webrtc/modules/rtp_rtcp/source/rtcp_sender.cc
diff --git a/webrtc/modules/rtp_rtcp/source/rtcp_sender.cc b/webrtc/modules/rtp_rtcp/source/rtcp_sender.cc
index a5fccebad1dd67eb792fcf70ae402fafdcac5700..0a0304e485c97a8d984d6d852ed6402d9dcd4043 100644
--- a/webrtc/modules/rtp_rtcp/source/rtcp_sender.cc
+++ b/webrtc/modules/rtp_rtcp/source/rtcp_sender.cc
@@ -207,13 +207,17 @@ RtcpMode RTCPSender::Status() const {
 
 void RTCPSender::SetRTCPStatus(RtcpMode method) {
   rtc::CritScope lock(&critical_section_rtcp_sender_);
+  bool was_off = (method_ == RtcpMode::kOff);

[pbos-webrtc, 2016/03/29 17:48:46]

remove ()s

[skvlad, 2016/03/29 18:09:25]

Done.

   method_ = method;
 
   if (method == RtcpMode::kOff)
     return;
-  next_time_to_send_rtcp_ =
-      clock_->TimeInMilliseconds() +
-      (audio_ ? RTCP_INTERVAL_AUDIO_MS / 2 : RTCP_INTERVAL_VIDEO_MS / 2);
+
+  if (was_off) {
+    next_time_to_send_rtcp_ =
+        clock_->TimeInMilliseconds() +
+        (audio_ ? RTCP_INTERVAL_AUDIO_MS / 2 : RTCP_INTERVAL_VIDEO_MS / 2);
+  }

[pthatcher1, 2016/03/25 23:03:40]

Might be more clear as:

if (method == method_)
  return;

method_ = method;

if (method == RtcpMode::kOff)
  return;

next_time_to_send_rtcp_ = ...;


Only the first early return needs to be added.

[skvlad, 2016/03/29 18:09:25]

There are three possible values for RtcpMode: kOff, kCompound, and kReducedSize.
My understanding is that only switching from kOff to one of the active modes
should reschedule the packet.

Rewriting the condition as you described does indeed make it clearer, but it
makes the RTCP packet be rescheduled when the mode is changed from kCompound to
kReducedSize which is probably not necessary.

[pthatcher, 2016/03/29 18:53:09]

Ah, true.


Well, how about this?

if (method == method_)
  return;

if (method_ == RtcpMode::kOff)
  // When switching off => on, reschedule.
  next_time_to_send_rtcp_ = ...;

method_ = method;

[skvlad, 2016/03/29 19:51:31]

Good idea; i've replaced it with a slightly modified version of this. Please
take a look.

 }
 
 bool RTCPSender::Sending() const {