Add overhead to audio bwe min, max.

webrtc/media/engine/webrtcvoiceengine.cc

Index: webrtc/media/engine/webrtcvoiceengine.cc
diff --git a/webrtc/media/engine/webrtcvoiceengine.cc b/webrtc/media/engine/webrtcvoiceengine.cc
index 96f9ed70d403c6c464cc9b015f83190630a0b331..b91529cb567106a869fd89a49ab3de7ce54360ad 100644
--- a/webrtc/media/engine/webrtcvoiceengine.cc
+++ b/webrtc/media/engine/webrtcvoiceengine.cc
@@ -1420,8 +1420,23 @@ class WebRtcVoiceMediaChannel::WebRtcAudioSendStream
         "Enabled") {
       // TODO(mflodman): Keep testing this and set proper values.
       // Note: This is an early experiment currently only supported by Opus.
-      config_.min_bitrate_bps = kOpusMinBitrateBps;
-      config_.max_bitrate_bps = kOpusBitrateFbBps;
+      if (webrtc::field_trial::FindFullName(
+              "WebRTC-SendSideBwe-WithOverhead") == "Enabled") {
+        // TODO(michaelt): We should let the audio encoder decide which max/min
+        // bitrate he would prefer.

[minyue-webrtc, 2017/01/10 22:16:19]

he -> it

+
+        // OverheadPerPacket(58) = Ipv4(20B) + UDP(8B) + SRTP(10B) + RTP(12)
+        //     + RTP_ext(8);
+        // kMaxOverheadBps = OverheadPerPacket * 8 * 1000ms / frame_length(20ms)

[the sun, 2017/01/09 15:03:55]

nit: make the order
min
max
throughout the block.

[michaelt, 2017/01/09 15:56:57]

Done.

+        // kMinOverheadBps = OverheadPerPacket * 8 * 1000ms / frame_length(60ms)
+        constexpr int kMaxOverheadBps = 23200;
+        constexpr int kMinOverheadBps = 7733;
+        config_.min_bitrate_bps = kOpusMinBitrateBps + kMinOverheadBps;
+        config_.max_bitrate_bps = kOpusBitrateFbBps + kMaxOverheadBps;
+      } else {
+        config_.min_bitrate_bps = kOpusMinBitrateBps;
+        config_.max_bitrate_bps = kOpusBitrateFbBps;
+      }
     }
     stream_ = call_->CreateAudioSendStream(config_);
     RTC_CHECK(stream_);