Periodically update codec bit/frame rate settings.

webrtc/media/engine/simulcast.cc

Index: webrtc/media/engine/simulcast.cc
diff --git a/webrtc/media/engine/simulcast.cc b/webrtc/media/engine/simulcast.cc
index 4dd8c3147b8c1502bb88b4725bf337f7b89ee584..f1cd2ced459810b03b1737632f947cf5d08a0b6d 100644
--- a/webrtc/media/engine/simulcast.cc
+++ b/webrtc/media/engine/simulcast.cc
@@ -49,7 +49,7 @@ const SimulcastFormat kSimulcastFormats[] = {
   {0, 0, 1, 200, 150, 30}
 };
 
-const int kMaxScreenshareSimulcastStreams = 2;
+const int kDefaultScreenshareSimulcastStreams = 2;
 
 // Multiway: Number of temporal layers for each simulcast stream, for maximum
 // possible number of simulcast streams |kMaxSimulcastStreams|. The array
@@ -176,12 +176,8 @@ std::vector<webrtc::VideoStream> GetSimulcastConfig(size_t max_streams,
                                                     bool is_screencast) {
   size_t num_simulcast_layers;
   if (is_screencast) {
-    if (UseSimulcastScreenshare()) {
-      num_simulcast_layers =
-          std::min<int>(max_streams, kMaxScreenshareSimulcastStreams);
-    } else {
-      num_simulcast_layers = 1;
-    }
+    num_simulcast_layers =
+        UseSimulcastScreenshare() ? kDefaultScreenshareSimulcastStreams : 1;
   } else {
     num_simulcast_layers = FindSimulcastMaxLayers(width, height);
   }
@@ -198,60 +194,33 @@ std::vector<webrtc::VideoStream> GetSimulcastConfig(size_t max_streams,
   std::vector<webrtc::VideoStream> streams;
   streams.resize(num_simulcast_layers);
 
-  if (is_screencast) {
-    ScreenshareLayerConfig config = ScreenshareLayerConfig::GetDefault();
-    // For legacy 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().
-    streams[0].width = width;
-    streams[0].height = height;
-    streams[0].max_qp = max_qp;
-    streams[0].max_framerate = 5;
-    streams[0].min_bitrate_bps = kMinVideoBitrateKbps * 1000;
-    streams[0].target_bitrate_bps = config.tl0_bitrate_kbps * 1000;
-    streams[0].max_bitrate_bps = config.tl1_bitrate_kbps * 1000;
-    streams[0].temporal_layer_thresholds_bps.clear();
-    streams[0].temporal_layer_thresholds_bps.push_back(config.tl0_bitrate_kbps *
-                                                       1000);
-
-    // With simulcast enabled, add another spatial layer. This one will have a
-    // more normal layout, with the regular 3 temporal layer pattern and no fps
-    // restrictions. The base simulcast stream will still use legacy setup.
-    if (num_simulcast_layers == kMaxScreenshareSimulcastStreams) {
-      // Add optional upper simulcast layer.
-      // Lowest temporal layers of a 3 layer setup will have 40% of the total
-      // bitrate allocation for that stream. Make sure the gap between the
-      // target of the lower stream and first temporal layer of the higher one
-      // is at most 2x the bitrate, so that upswitching is not hampered by
-      // stalled bitrate estimates.
-      int max_bitrate_bps = 2 * ((streams[0].target_bitrate_bps * 10) / 4);
-      // Cap max bitrate so it isn't overly high for the given resolution.
-      max_bitrate_bps = std::min<int>(
-          max_bitrate_bps, FindSimulcastMaxBitrateBps(width, height));
-
-      streams[1].width = width;
-      streams[1].height = height;
-      streams[1].max_qp = max_qp;
-      streams[1].max_framerate = max_framerate;
-      // Three temporal layers means two thresholds.
-      streams[1].temporal_layer_thresholds_bps.resize(2);
-      streams[1].min_bitrate_bps = streams[0].target_bitrate_bps * 2;
-      streams[1].target_bitrate_bps = max_bitrate_bps;
-      streams[1].max_bitrate_bps = max_bitrate_bps;
-    }
-  } else {
+  if (!is_screencast) {
     // Format width and height has to be divisible by |2 ^ number_streams - 1|.
     width = NormalizeSimulcastSize(width, num_simulcast_layers);
     height = NormalizeSimulcastSize(height, num_simulcast_layers);
+  }
 
-    // Add simulcast sub-streams from lower resolution to higher resolutions.
-    // Add simulcast streams, from highest resolution (|s| = number_streams -1)
-    // to lowest resolution at |s| = 0.
-    for (size_t s = num_simulcast_layers - 1;; --s) {
-      streams[s].width = width;
-      streams[s].height = height;
-      // TODO(pbos): Fill actual temporal-layer bitrate thresholds.
-      streams[s].max_qp = max_qp;
+  // Add simulcast sub-streams from lower resolution to higher resolutions.
+  // Add simulcast streams, from highest resolution (|s| = number_streams -1)
+  // to lowest resolution at |s| = 0.
+  for (size_t s = num_simulcast_layers - 1;; --s) {
+    streams[s].width = width;
+    streams[s].height = height;
+    // TODO(pbos): Fill actual temporal-layer bitrate thresholds.
+    streams[s].max_qp = max_qp;
+    if (is_screencast && s == 0) {
+      ScreenshareLayerConfig config = ScreenshareLayerConfig::GetDefault();
+      // For legacy 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().
+      streams[s].min_bitrate_bps = kMinVideoBitrateKbps * 1000;
+      streams[s].target_bitrate_bps = config.tl0_bitrate_kbps * 1000;
+      streams[s].max_bitrate_bps = config.tl1_bitrate_kbps * 1000;
+      streams[s].temporal_layer_thresholds_bps.clear();
+      streams[s].temporal_layer_thresholds_bps.push_back(
+          config.tl0_bitrate_kbps * 1000);
+      streams[s].max_framerate = 5;
+    } else {
       streams[s].temporal_layer_thresholds_bps.resize(
           kDefaultConferenceNumberOfTemporalLayers[s] - 1);
       streams[s].max_bitrate_bps = FindSimulcastMaxBitrateBps(width, height);
@@ -259,19 +228,20 @@ std::vector<webrtc::VideoStream> GetSimulcastConfig(size_t max_streams,
           FindSimulcastTargetBitrateBps(width, height);
       streams[s].min_bitrate_bps = FindSimulcastMinBitrateBps(width, height);
       streams[s].max_framerate = max_framerate;
+    }
 
+    if (!is_screencast) {
       width /= 2;
       height /= 2;
-
-      if (s == 0)
-        break;
     }
+    if (s == 0)
+      break;
+  }
 
-    // Spend additional bits to boost the max stream.
-    int bitrate_left_bps = max_bitrate_bps - GetTotalMaxBitrateBps(streams);
-    if (bitrate_left_bps > 0) {
-      streams.back().max_bitrate_bps += bitrate_left_bps;
-    }
+  // Spend additional bits to boost the max stream.
+  int bitrate_left_bps = max_bitrate_bps - GetTotalMaxBitrateBps(streams);
+  if (bitrate_left_bps > 0) {
+    streams.back().max_bitrate_bps += bitrate_left_bps;
   }
 
   return streams;