Set actual transport overhead in rtp_rtcp

webrtc/pc/channel.cc

Index: webrtc/pc/channel.cc
diff --git a/webrtc/pc/channel.cc b/webrtc/pc/channel.cc
index f22bdc4ca41029155f2fe4fe511bb9c2765ee679..406c2a6e93ea13b7e02bc6abb302f03e25bc6dc1 100644
--- a/webrtc/pc/channel.cc
+++ b/webrtc/pc/channel.cc
@@ -586,7 +586,14 @@ void BaseChannel::OnSelectedCandidatePairChanged(
         ready_to_send, selected_candidate_pair->local_candidate().network_id(),
         selected_candidate_pair->remote_candidate().network_id(),
         last_sent_packet_id);
+
+    invoker_.AsyncInvoke<void>(
+        RTC_FROM_HERE, worker_thread_,
+        Bind(&MediaChannel::OnTransportOverheadChange, media_channel_,
+             GetTransportOverheadPerPacket(
+                 selected_candidate_pair->local_candidate())));
   }
+
   invoker_.AsyncInvoke<void>(
       RTC_FROM_HERE, worker_thread_,
       Bind(&MediaChannel::OnNetworkRouteChanged, media_channel_, transport_name,
@@ -1030,11 +1037,15 @@ bool BaseChannel::SetupDtlsSrtp_n(bool rtcp_channel) {
                                     static_cast<int>(recv_key->size()));
   }
 
-  if (!ret)
+  if (!ret) {
     LOG(LS_WARNING) << "DTLS-SRTP key installation failed";
-  else
+  } else {
     dtls_keyed_ = true;
-
+    invoker_.AsyncInvoke<void>(
+        RTC_FROM_HERE, worker_thread_,
+        Bind(&MediaChannel::OnTransportOverheadChange, media_channel_,
+             GetTransportOverheadPerPacket()));
+  }
   return ret;
 }
 
@@ -1661,6 +1672,42 @@ void BaseChannel::UpdateMediaSendRecvState() {
       Bind(&BaseChannel::UpdateMediaSendRecvState_w, this));
 }
 
+int BaseChannel::GetTransportOverheadPerPacket() {
+  if (transport_channel_) {
+    std::vector<ConnectionInfo> connection_infos;
+    transport_channel_->GetStats(&connection_infos);

[honghaiz3, 2016/10/27 18:57:44]

Does it make sense to just remember the last signaled candidate pair so that you
don't have to find the best connection via GetStats?
That way, you don't need two methods to get the overhead. 
Another choice would be to add a virtual method selected_connection in the
transportchannel. 

[michaelt, 2016/10/31 09:59:26]

store now the last signaled candidate pair in channel.

+    for (auto& connection_info : connection_infos) {
+      if (connection_info.best_connection) {
+        return GetTransportOverheadPerPacket(connection_info.local_candidate);
+        break;

[honghaiz3, 2016/10/27 18:57:44]

You don't need a break after return. 

[michaelt, 2016/10/31 09:59:26]

:)
I removed the function.

+      }
+    }
+  }
+  return 0;
+}
+
+int BaseChannel::GetTransportOverheadPerPacket(
+    const Candidate& local_candidate) {
+  constexpr int kIpv4Overhaed = 20;
+  constexpr int kIpv6Overhaed = 40;
+  constexpr int kUdpOverhaed = 8;
+  constexpr int kTcpOverhaed = 20;
+
+  int transport_overhead_per_packet = 0;
+  transport_overhead_per_packet +=
+      local_candidate.protocol() == TCP_PROTOCOL_NAME ? kTcpOverhaed
+                                                      : kUdpOverhaed;
+  transport_overhead_per_packet += local_candidate.address().family() == AF_INET
+                                       ? kIpv4Overhaed
+                                       : kIpv6Overhaed;
+  if (secure()) {
+    int srtp_overhead = 0;
+    if (srtp_filter_.GetSrtpOverhead(&srtp_overhead))
+      transport_overhead_per_packet += srtp_overhead;
+  }
+  return transport_overhead_per_packet;
+}
+
 void VoiceChannel::UpdateMediaSendRecvState_w() {
   // Render incoming data if we're the active call, and we have the local
   // content. We receive data on the default channel and multiplexed streams.