screenshare_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.

*/

#ifndef MODULES_VIDEO_CODING_CODECS_VP8_SCREENSHARE_LAYERS_H_

#define MODULES_VIDEO_CODING_CODECS_VP8_SCREENSHARE_LAYERS_H_

#include <map>

#include <memory>

#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"

#include "modules/video_coding/utility/frame_dropper.h"

#include "rtc_base/numerics/sequence_number_unwrapper.h"

#include "rtc_base/rate_statistics.h"

namespace webrtc {

struct CodecSpecificInfoVP8;

class Clock;

class ScreenshareLayers final : public Vp8FrameBufferController {

 public:

  static const double kMaxTL0FpsReduction;

  static const double kAcceptableTargetOvershoot;

  static const int kMaxFrameIntervalMs;

  explicit ScreenshareLayers(int num_temporal_layers);

  ~ScreenshareLayers() 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 rtp_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;

  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:

  enum class TemporalLayerState : int { kDrop, kTl0, kTl1, kTl1Sync };

  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;

};

  bool TimeToSync(int64_t timestamp) const;

  uint32_t GetCodecTargetBitrateKbps() const;

  const int number_of_temporal_layers_;

  // TODO(eladalon/sprang): These should be made into const-int set in the ctor.

  std::optional<int> min_qp_;

  std::optional<int> max_qp_;

  int active_layer_;

  int64_t last_timestamp_;

  int64_t last_sync_timestamp_;

  int64_t last_emitted_tl0_timestamp_;

  int64_t last_frame_time_ms_;

  RtpTimestampUnwrapper time_wrap_handler_;

  uint32_t max_debt_bytes_;

  std::map<uint32_t, DependencyInfo> pending_frame_configs_;

  // Configured max framerate.

  std::optional<uint32_t> target_framerate_;

  // Incoming framerate from capturer.

  std::optional<uint32_t> capture_framerate_;

  // Tracks what framerate we actually encode, and drops frames on overshoot.

  RateStatistics encode_framerate_;

  bool bitrate_updated_;

  static constexpr int kMaxNumTemporalLayers = 2;

  struct TemporalLayer {

    TemporalLayer()

        : state(State::kNormal),

          enhanced_max_qp(-1),

          last_qp(-1),

          debt_bytes_(0),

          target_rate_kbps_(0) {}

    enum class State {

      kNormal,

      kDropped,

      kReencoded,

      kQualityBoost,

      kKeyFrame

    } state;

    int enhanced_max_qp;

    int last_qp;

    uint32_t debt_bytes_;

    uint32_t target_rate_kbps_;

    void UpdateDebt(int64_t delta_ms);

  } layers_[kMaxNumTemporalLayers];

  void UpdateHistograms();

  FrameDependencyStructure GetTemplateStructure(int num_layers) const;

  // Data for histogram statistics.

  struct Stats {

    int64_t first_frame_time_ms_ = -1;

    int64_t num_tl0_frames_ = 0;

    int64_t num_tl1_frames_ = 0;

    int64_t num_dropped_frames_ = 0;

    int64_t num_overshoots_ = 0;

    int64_t tl0_qp_sum_ = 0;

    int64_t tl1_qp_sum_ = 0;

    int64_t tl0_target_bitrate_sum_ = 0;

    int64_t tl1_target_bitrate_sum_ = 0;

  } stats_;

  Vp8EncoderConfig encoder_config_;

  // Optional utility used to verify reference validity.

  std::unique_ptr<TemporalLayersChecker> checker_;

};

}  // namespace webrtc

#endif  // MODULES_VIDEO_CODING_CODECS_VP8_SCREENSHARE_LAYERS_H_