default_temporal_layers.h

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/* Copyright (c) 2013 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.

*/

/*

 * This file defines classes for doing temporal layers with VP8.

*/

#ifndef MODULES_VIDEO_CODING_CODECS_VP8_DEFAULT_TEMPORAL_LAYERS_H_

#define MODULES_VIDEO_CODING_CODECS_VP8_DEFAULT_TEMPORAL_LAYERS_H_

#include <stddef.h>

#include <stdint.h>

#include <bitset>

#include <deque>

#include <limits>

#include <memory>

#include <optional>

#include <set>

#include <utility>

#include <vector>

#include "api/video_codecs/vp8_frame_config.h"

#include "api/video_codecs/vp8_temporal_layers.h"

#include "modules/video_coding/codecs/vp8/include/temporal_layers_checker.h"

#include "modules/video_coding/include/video_codec_interface.h"

namespace webrtc {

class DefaultTemporalLayers final : public Vp8FrameBufferController {

 public:

  explicit DefaultTemporalLayers(int number_of_temporal_layers);

  ~DefaultTemporalLayers() override;

  void SetQpLimits(size_t stream_index, int min_qp, int max_qp) override;

  size_t StreamCount() const override;

  bool SupportsEncoderFrameDropping(size_t stream_index) const override;

  // Returns the recommended VP8 encode flags needed. May refresh the decoder

  // and/or update the reference buffers.

  Vp8FrameConfig NextFrameConfig(size_t stream_index,

                                 uint32_t timestamp) override;

  // New target bitrate, per temporal layer.

  void OnRatesUpdated(size_t stream_index,

                      const std::vector<uint32_t>& bitrates_bps,

                      int framerate_fps) override;

  Vp8EncoderConfig UpdateConfiguration(size_t stream_index) override;

  // Callbacks methods on frame completion. OnEncodeDone() or OnFrameDropped()

  // should be called once for each NextFrameConfig() call (using the RTP

  // timestamp as ID), and the calls MUST be in the same order.

  void OnEncodeDone(size_t stream_index,

                    uint32_t rtp_timestamp,

                    size_t size_bytes,

                    bool is_keyframe,

                    int qp,

                    CodecSpecificInfo* info) override;

  void OnFrameDropped(size_t stream_index, uint32_t rtp_timestamp) override;

  void OnPacketLossRateUpdate(float packet_loss_rate) override;

  void OnRttUpdate(int64_t rtt_ms) override;

  void OnLossNotification(

      const VideoEncoder::LossNotification& loss_notification) override;

 private:

  static constexpr size_t kNumReferenceBuffers = 3;  // Last, golden, altref.

  struct DependencyInfo {

    DependencyInfo() = default;

    DependencyInfo(absl::string_view indication_symbols,

                   Vp8FrameConfig frame_config)

        : decode_target_indications(

              webrtc_impl::StringToDecodeTargetIndications(indication_symbols)),

          frame_config(frame_config) {}

    absl::InlinedVector<DecodeTargetIndication, 10> decode_target_indications;

    Vp8FrameConfig frame_config;

};

  struct PendingFrame {

    PendingFrame();

    PendingFrame(uint32_t timestamp,

                 bool expired,

                 uint8_t updated_buffers_mask,

                 const DependencyInfo& dependency_info);

    uint32_t timestamp = 0;

    // Flag indicating if this frame has expired, ie it belongs to a previous

    // iteration of the temporal pattern.

    bool expired = false;

    // Bitmask of Vp8BufferReference flags, indicating which buffers this frame

    // updates.

    uint8_t updated_buffer_mask = 0;

    // The frame config returned by NextFrameConfig() for this frame.

    DependencyInfo dependency_info;

};

  static std::vector<DependencyInfo> GetDependencyInfo(size_t num_layers);

  static std::bitset<kNumReferenceBuffers> DetermineStaticBuffers(

      const std::vector<DependencyInfo>& temporal_pattern);

  bool IsSyncFrame(const Vp8FrameConfig& config) const;

  void ValidateReferences(Vp8FrameConfig::BufferFlags* flags,

                          Vp8FrameConfig::Vp8BufferReference ref) const;

  void UpdateSearchOrder(Vp8FrameConfig* config);

  size_t NumFramesSinceBufferRefresh(

      Vp8FrameConfig::Vp8BufferReference ref) const;

  void ResetNumFramesSinceBufferRefresh(Vp8FrameConfig::Vp8BufferReference ref);

  void CullPendingFramesBefore(uint32_t timestamp);

  const size_t num_layers_;

  const std::vector<unsigned int> temporal_ids_;

  const std::vector<DependencyInfo> temporal_pattern_;

  // Per reference buffer flag indicating if it is static, meaning it is only

  // updated by key-frames.

  const std::bitset<kNumReferenceBuffers> is_static_buffer_;

  FrameDependencyStructure GetTemplateStructure(int num_layers) const;

  uint8_t pattern_idx_;

  // Updated cumulative bitrates, per temporal layer.

  std::optional<std::vector<uint32_t>> new_bitrates_bps_;

  // Status for each pending frame, in

  std::deque<PendingFrame> pending_frames_;

  // One counter per reference buffer, indicating number of frames since last

  // refresh. For non-base-layer frames (ie golden, altref buffers), this is

  // reset when the pattern loops.

  std::array<size_t, kNumReferenceBuffers> frames_since_buffer_refresh_;

  // Optional utility used to verify reference validity.

  std::unique_ptr<TemporalLayersChecker> checker_;

};

class DefaultTemporalLayersChecker : public TemporalLayersChecker {

 public:

  explicit DefaultTemporalLayersChecker(int number_of_temporal_layers);

  ~DefaultTemporalLayersChecker() override;

  bool CheckTemporalConfig(bool frame_is_keyframe,

                           const Vp8FrameConfig& frame_config) override;

 private:

  struct BufferState {

    BufferState()

        : is_updated_this_cycle(false), is_keyframe(true), pattern_idx(0) {}

    bool is_updated_this_cycle;

    bool is_keyframe;

    uint8_t pattern_idx;

};

  const size_t num_layers_;

  std::vector<unsigned int> temporal_ids_;

  const std::vector<std::set<uint8_t>> temporal_dependencies_;

  BufferState last_;

  BufferState arf_;

  BufferState golden_;

  uint8_t pattern_idx_;

};

}  // namespace webrtc

#endif  // MODULES_VIDEO_CODING_CODECS_VP8_DEFAULT_TEMPORAL_LAYERS_H_