In screenshare mode, suppress VP8 bitrate overshoot and increase quality

talk/media/webrtc/simulcast.cc

 /*
  * libjingle
  * Copyright 2014 Google Inc.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are met:
  *
  *  1. Redistributions of source code must retain the above copyright notice,
  *     this list of conditions and the following disclaimer.
  *  2. Redistributions in binary form must reproduce the above copyright notice,
@@ skipping 393 matching lines @@
                  << codec.simulcastStream[i].maxBitrate << "kbps"
                  << " with "
                  << static_cast<int>(
                      codec.simulcastStream[i].numberOfTemporalLayers)
                  << " temporal layers";
   }
 }
 
 static const int kScreenshareMinBitrateKbps = 50;
 static const int kScreenshareMaxBitrateKbps = 6000;
-static const int kScreenshareDefaultTl0BitrateKbps = 100;
+static const int kScreenshareDefaultTl0BitrateKbps = 200;
 static const int kScreenshareDefaultTl1BitrateKbps = 1000;
 
 static const char* kScreencastLayerFieldTrialName =
     "WebRTC-ScreenshareLayerRates";
 
 ScreenshareLayerConfig::ScreenshareLayerConfig(int tl0_bitrate, int tl1_bitrate)
     : tl0_bitrate_kbps(tl0_bitrate), tl1_bitrate_kbps(tl1_bitrate) {
 }
 
 ScreenshareLayerConfig ScreenshareLayerConfig::GetDefault() {
@@ skipping 39 matching lines @@
   ScreenshareLayerConfig config = ScreenshareLayerConfig::GetDefault();
 
   // For screenshare in conference mode, tl0 and tl1 bitrates are piggybacked
   // on the VideoCodec struct as target and max bitrates, respectively.
   // See eg. webrtc::VP8EncoderImpl::SetRates().
   codec->targetBitrate = config.tl0_bitrate_kbps;
   codec->maxBitrate = config.tl1_bitrate_kbps;
 }
 
 }  // namespace cricket