Reland of Work on flexible mode and screen sharing.

webrtc/modules/video_coding/codecs/vp9/screenshare_layers.h

Index: webrtc/modules/video_coding/codecs/vp9/screenshare_layers.h
diff --git a/webrtc/modules/video_coding/codecs/vp9/screenshare_layers.h b/webrtc/modules/video_coding/codecs/vp9/screenshare_layers.h
new file mode 100644
index 0000000000000000000000000000000000000000..5a901ae359c5354d002d7e38c3e58dab09460b35
--- /dev/null
+++ b/webrtc/modules/video_coding/codecs/vp9/screenshare_layers.h
@@ -0,0 +1,66 @@
+/* Copyright (c) 2015 The WebRTC project authors. All Rights Reserved.
+*
+*  Use of this source code is governed by a BSD-style license
+*  that can be found in the LICENSE file in the root of the source
+*  tree. An additional intellectual property rights grant can be found
+*  in the file PATENTS.  All contributing project authors may
+*  be found in the AUTHORS file in the root of the source tree.
+*/
+
+#ifndef WEBRTC_MODULES_VIDEO_CODING_CODECS_VP9_SCREENSHARE_LAYERS_H_
+#define WEBRTC_MODULES_VIDEO_CODING_CODECS_VP9_SCREENSHARE_LAYERS_H_
+
+#include "webrtc/modules/video_coding/codecs/vp9/vp9_impl.h"
+
+namespace webrtc {
+
+class ScreenshareLayersVP9 {
+ public:
+  explicit ScreenshareLayersVP9(uint8_t num_layers);
+
+  // The target bitrate for layer with id layer_id.
+  void ConfigureBitrate(int threshold_kbps, uint8_t layer_id);
+
+  // The current start layer.
+  uint8_t GetStartLayer() const;
+
+  // Update the layer with the size of the layer frame.
+  void LayerFrameEncoded(unsigned int size_bytes, uint8_t layer_id);
+
+  // Get the layer settings for the next superframe.
+  //
+  // In short, each time the GetSuperFrameSettings is called the
+  // bitrate of every layer is calculated and if the cummulative
+  // bitrate exceeds the configured cummulative bitrates
+  // (ConfigureBitrate to configure) up to and including that
+  // layer then the resulting encoding settings for the
+  // superframe will only encode layers above that layer.
+  VP9EncoderImpl::SuperFrameRefSettings GetSuperFrameSettings(
+      uint32_t timestamp,
+      bool is_keyframe);
+
+ private:
+  // How many layers that are used.
+  uint8_t num_layers_;
+
+  // The index of the first layer to encode.
+  uint8_t start_layer_;
+
+  // Cummulative target kbps for the different layers.
+  float threshold_kbps_[kMaxVp9NumberOfSpatialLayers - 1];
+
+  // How many bits that has been used for a certain layer. Increased in
+  // FrameEncoded() by the size of the encoded frame and decreased in
+  // GetSuperFrameSettings() depending on the time between frames.
+  float bits_used_[kMaxVp9NumberOfSpatialLayers];
+
+  // Timestamp of last frame.
+  uint32_t last_timestamp_;
+
+  // If the last_timestamp_ has been set.
+  bool timestamp_initialized_;
+};
+
+}  // namespace webrtc
+
+#endif  // WEBRTC_MODULES_VIDEO_CODING_CODECS_VP9_SCREENSHARE_LAYERS_H_