Move scalability structures from av1 into own subfolder

To make it natural to reuse them for vp9

Bug: webrtc:11999
Change-Id: If2ef7ca16b8be96e0e03bb19211d9f5eb74b2d3d
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/188620
Reviewed-by: Philip Eliasson <philipel@webrtc.org>
Commit-Queue: Danil Chapovalov <danilchap@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#32414}

modules/video_coding/svc/scalable_video_controller.h

@@ -0,0 +1,139 @@
+/*
+ *  Copyright (c) 2020 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_SCALABLE_VIDEO_CONTROLLER_H_
+#define MODULES_VIDEO_CODING_SVC_SCALABLE_VIDEO_CONTROLLER_H_
+
+#include <vector>
+
+#include "absl/container/inlined_vector.h"
+#include "api/transport/rtp/dependency_descriptor.h"
+#include "api/video/video_bitrate_allocation.h"
+#include "common_video/generic_frame_descriptor/generic_frame_info.h"
+
+namespace webrtc {
+
+// Controls how video should be encoded to be scalable. Outputs results as
+// buffer usage configuration for encoder and enough details to communicate the
+// scalability structure via dependency descriptor rtp header extension.
+class ScalableVideoController {
+ public:
+  struct StreamLayersConfig {
+    int num_spatial_layers = 1;
+    int num_temporal_layers = 1;
+    // Spatial layers scaling. Frames with spatial_id = i expected to be encoded
+    // with original_resolution * scaling_factor_num[i] / scaling_factor_den[i].
+    int scaling_factor_num[DependencyDescriptor::kMaxSpatialIds] = {1, 1, 1, 1};
+    int scaling_factor_den[DependencyDescriptor::kMaxSpatialIds] = {1, 1, 1, 1};
+  };
+  class LayerFrameConfig {
+   public:
+    // Builders/setters.
+    LayerFrameConfig& Id(int value);
+    LayerFrameConfig& Keyframe();
+    LayerFrameConfig& S(int value);
+    LayerFrameConfig& T(int value);
+    LayerFrameConfig& Reference(int buffer_id);
+    LayerFrameConfig& Update(int buffer_id);
+    LayerFrameConfig& ReferenceAndUpdate(int buffer_id);
+
+    // Getters.
+    int Id() const { return id_; }
+    bool IsKeyframe() const { return is_keyframe_; }
+    int SpatialId() const { return spatial_id_; }
+    int TemporalId() const { return temporal_id_; }
+    const absl::InlinedVector<CodecBufferUsage, kMaxEncoderBuffers>& Buffers()
+        const {
+      return buffers_;
+    }
+
+   private:
+    // Id to match configuration returned by NextFrameConfig with
+    // (possibly modified) configuration passed back via OnEncoderDone.
+    // The meaning of the id is an implementation detail of
+    // the ScalableVideoController.
+    int id_ = 0;
+
+    // Indication frame should be encoded as a key frame. In particular when
+    // `is_keyframe=true` property `CodecBufferUsage::referenced` should be
+    // ignored and treated as false.
+    bool is_keyframe_ = false;
+
+    int spatial_id_ = 0;
+    int temporal_id_ = 0;
+    // Describes how encoder which buffers encoder allowed to reference and
+    // which buffers encoder should update.
+    absl::InlinedVector<CodecBufferUsage, kMaxEncoderBuffers> buffers_;
+  };
+
+  virtual ~ScalableVideoController() = default;
+
+  // Returns video structure description for encoder to configure itself.
+  virtual StreamLayersConfig StreamConfig() const = 0;
+
+  // Returns video structure description in format compatible with
+  // dependency descriptor rtp header extension.
+  virtual FrameDependencyStructure DependencyStructure() const = 0;
+
+  // Notifies Controller with updated bitrates per layer. In particular notifies
+  // when certain layers should be disabled.
+  // Controller shouldn't produce LayerFrameConfig for disabled layers.
+  // TODO(bugs.webrtc.org/11404): Make pure virtual when implemented by all
+  // structures.
+  virtual void OnRatesUpdated(const VideoBitrateAllocation& bitrates) {}
+
+  // When `restart` is true, first `LayerFrameConfig` should have `is_keyframe`
+  // set to true.
+  // Returned vector shouldn't be empty.
+  virtual std::vector<LayerFrameConfig> NextFrameConfig(bool restart) = 0;
+
+  // Returns configuration to pass to EncoderCallback.
+  virtual GenericFrameInfo OnEncodeDone(const LayerFrameConfig& config) = 0;
+};
+
+// Below are implementation details.
+inline ScalableVideoController::LayerFrameConfig&
+ScalableVideoController::LayerFrameConfig::Id(int value) {
+  id_ = value;
+  return *this;
+}
+inline ScalableVideoController::LayerFrameConfig&
+ScalableVideoController::LayerFrameConfig::Keyframe() {
+  is_keyframe_ = true;
+  return *this;
+}
+inline ScalableVideoController::LayerFrameConfig&
+ScalableVideoController::LayerFrameConfig::S(int value) {
+  spatial_id_ = value;
+  return *this;
+}
+inline ScalableVideoController::LayerFrameConfig&
+ScalableVideoController::LayerFrameConfig::T(int value) {
+  temporal_id_ = value;
+  return *this;
+}
+inline ScalableVideoController::LayerFrameConfig&
+ScalableVideoController::LayerFrameConfig::Reference(int buffer_id) {
+  buffers_.emplace_back(buffer_id, /*referenced=*/true, /*updated=*/false);
+  return *this;
+}
+inline ScalableVideoController::LayerFrameConfig&
+ScalableVideoController::LayerFrameConfig::Update(int buffer_id) {
+  buffers_.emplace_back(buffer_id, /*referenced=*/false, /*updated=*/true);
+  return *this;
+}
+inline ScalableVideoController::LayerFrameConfig&
+ScalableVideoController::LayerFrameConfig::ReferenceAndUpdate(int buffer_id) {
+  buffers_.emplace_back(buffer_id, /*referenced=*/true, /*updated=*/true);
+  return *this;
+}
+
+}  // namespace webrtc
+
+#endif  // MODULES_VIDEO_CODING_SVC_SCALABLE_VIDEO_CONTROLLER_H_