text: /*
   *  Copyright (c) 2016 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_RTP_FRAME_REFERENCE_FINDER_H_
  #define MODULES_VIDEO_CODING_RTP_FRAME_REFERENCE_FINDER_H_
  
  #include <memory>
  
  #include "modules/video_coding/frame_object.h"
  
  namespace webrtc {
  namespace internal {
  class RtpFrameReferenceFinderImpl;
  }  // namespace internal
  
  // A complete frame is a frame which has received all its packets and all its
  // references are known.
  class OnCompleteFrameCallback {
   public:
    virtual ~OnCompleteFrameCallback() {}
    virtual void OnCompleteFrame(std::unique_ptr<EncodedFrame> frame) = 0;
  };
  
  class RtpFrameReferenceFinder {
   public:
    using ReturnVector = absl::InlinedVector<std::unique_ptr<RtpFrameObject>, 3>;
  
    explicit RtpFrameReferenceFinder(OnCompleteFrameCallback* frame_callback);
    explicit RtpFrameReferenceFinder(OnCompleteFrameCallback* frame_callback,
                                     int64_t picture_id_offset);
    ~RtpFrameReferenceFinder();
  
    // Manage this frame until:
    //  - We have all information needed to determine its references, after
    //    which |frame_callback_| is called with the completed frame, or
    //  - We have too many stashed frames (determined by |kMaxStashedFrames|)
    //    so we drop this frame, or
    //  - It gets cleared by ClearTo, which also means we drop it.
    void ManageFrame(std::unique_ptr<RtpFrameObject> frame);
  
    // Notifies that padding has been received, which the reference finder
    // might need to calculate the references of a frame.
    void PaddingReceived(uint16_t seq_num);
  
    // Clear all stashed frames that include packets older than |seq_num|.
    void ClearTo(uint16_t seq_num);
  
   private:
    void HandOffFrames(ReturnVector frames);
  
    // How far frames have been cleared out of the buffer by RTP sequence number.
    // A frame will be cleared if it contains a packet with a sequence number
    // older than |cleared_to_seq_num_|.
    int cleared_to_seq_num_ = -1;
    const int64_t picture_id_offset_;
    OnCompleteFrameCallback* frame_callback_;
    std::unique_ptr<internal::RtpFrameReferenceFinderImpl> impl_;
  };
  
  }  // namespace webrtc
  
  #endif  // MODULES_VIDEO_CODING_RTP_FRAME_REFERENCE_FINDER_H_
  