Add S3T3 video scalability structure

Bug: None
Change-Id: I93760b501ff712ca2f7a9dfa3cba6ed5245e4f4b
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/208080
Reviewed-by: Philip Eliasson <philipel@webrtc.org>
Commit-Queue: Danil Chapovalov <danilchap@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#33297}

modules/video_coding/svc/scalability_structure_simulcast.h

@@ -0,0 +1,89 @@
+/*
+ *  Copyright (c) 2021 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 MODULES_VIDEO_CODING_SVC_SCALABILITY_STRUCTURE_SIMULCAST_H_
+#define MODULES_VIDEO_CODING_SVC_SCALABILITY_STRUCTURE_SIMULCAST_H_
+
+#include <vector>
+
+#include "api/transport/rtp/dependency_descriptor.h"
+#include "api/video/video_bitrate_allocation.h"
+#include "common_video/generic_frame_descriptor/generic_frame_info.h"
+#include "modules/video_coding/svc/scalable_video_controller.h"
+
+namespace webrtc {
+
+// Scalability structure with multiple independent spatial layers each with the
+// same temporal layering.
+class ScalabilityStructureSimulcast : public ScalableVideoController {
+ public:
+  ScalabilityStructureSimulcast(int num_spatial_layers,
+                                int num_temporal_layers);
+  ~ScalabilityStructureSimulcast() override;
+
+  StreamLayersConfig StreamConfig() const override;
+  std::vector<LayerFrameConfig> NextFrameConfig(bool restart) override;
+  GenericFrameInfo OnEncodeDone(const LayerFrameConfig& config) override;
+  void OnRatesUpdated(const VideoBitrateAllocation& bitrates) override;
+
+ private:
+  enum FramePattern {
+    kNone,
+    kDeltaT2A,
+    kDeltaT1,
+    kDeltaT2B,
+    kDeltaT0,
+  };
+  static constexpr int kMaxNumSpatialLayers = 3;
+  static constexpr int kMaxNumTemporalLayers = 3;
+
+  // Index of the buffer to store last frame for layer (`sid`, `tid`)
+  int BufferIndex(int sid, int tid) const {
+    return tid * num_spatial_layers_ + sid;
+  }
+  bool DecodeTargetIsActive(int sid, int tid) const {
+    return active_decode_targets_[sid * num_temporal_layers_ + tid];
+  }
+  void SetDecodeTargetIsActive(int sid, int tid, bool value) {
+    active_decode_targets_.set(sid * num_temporal_layers_ + tid, value);
+  }
+  FramePattern NextPattern() const;
+  bool TemporalLayerIsActive(int tid) const;
+
+  const int num_spatial_layers_;
+  const int num_temporal_layers_;
+
+  FramePattern last_pattern_ = kNone;
+  std::bitset<kMaxNumSpatialLayers> can_reference_t0_frame_for_spatial_id_ = 0;
+  std::bitset<kMaxNumSpatialLayers> can_reference_t1_frame_for_spatial_id_ = 0;
+  std::bitset<32> active_decode_targets_;
+};
+
+// S1  0--0--0-
+//             ...
+// S0  0--0--0-
+class ScalabilityStructureS2T1 : public ScalabilityStructureSimulcast {
+ public:
+  ScalabilityStructureS2T1() : ScalabilityStructureSimulcast(2, 1) {}
+  ~ScalabilityStructureS2T1() override = default;
+
+  FrameDependencyStructure DependencyStructure() const override;
+};
+
+class ScalabilityStructureS3T3 : public ScalabilityStructureSimulcast {
+ public:
+  ScalabilityStructureS3T3() : ScalabilityStructureSimulcast(3, 3) {}
+  ~ScalabilityStructureS3T3() override = default;
+
+  FrameDependencyStructure DependencyStructure() const override;
+};
+
+}  // namespace webrtc
+
+#endif  // MODULES_VIDEO_CODING_SVC_SCALABILITY_STRUCTURE_SIMULCAST_H_