rtp_seq_num_only_ref_finder.h

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/*

 *  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_RTP_SEQ_NUM_ONLY_REF_FINDER_H_

#define MODULES_VIDEO_CODING_RTP_SEQ_NUM_ONLY_REF_FINDER_H_

#include <deque>

#include <map>

#include <memory>

#include <set>

#include <utility>

#include "absl/container/inlined_vector.h"

#include "modules/rtp_rtcp/source/frame_object.h"

#include "modules/video_coding/rtp_frame_reference_finder.h"

#include "rtc_base/numerics/sequence_number_unwrapper.h"

namespace webrtc {

class RtpSeqNumOnlyRefFinder {

 public:

  RtpSeqNumOnlyRefFinder() = default;

  RtpFrameReferenceFinder::ReturnVector ManageFrame(

      std::unique_ptr<RtpFrameObject> frame);

  RtpFrameReferenceFinder::ReturnVector PaddingReceived(uint16_t seq_num);

  void ClearTo(uint16_t seq_num);

 private:

  static constexpr int kMaxStashedFrames = 100;

  static constexpr int kMaxPaddingAge = 100;

  enum FrameDecision { kStash, kHandOff, kDrop };

  FrameDecision ManageFrameInternal(RtpFrameObject* frame);

  void RetryStashedFrames(RtpFrameReferenceFinder::ReturnVector& res);

  void UpdateLastPictureIdWithPadding(uint16_t seq_num);

  // For every group of pictures, hold two sequence numbers. The first being

  // the sequence number of the last packet of the last completed frame, and

  // the second being the sequence number of the last packet of the last

  // completed frame advanced by any potential continuous packets of padding.

  std::map<uint16_t,

           std::pair<uint16_t, uint16_t>,

           DescendingSeqNumComp<uint16_t>>

      last_seq_num_gop_;

  // Padding packets that have been received but that are not yet continuous

  // with any group of pictures.

  std::set<uint16_t, DescendingSeqNumComp<uint16_t>> stashed_padding_;

  // Frames that have been fully received but didn't have all the information

  // needed to determine their references.

  std::deque<std::unique_ptr<RtpFrameObject>> stashed_frames_;

  // Unwrapper used to unwrap generic RTP streams. In a generic stream we derive

  // a picture id from the packet sequence number.

  SeqNumUnwrapper<uint16_t> rtp_seq_num_unwrapper_;

};

}  // namespace webrtc

#endif  // MODULES_VIDEO_CODING_RTP_SEQ_NUM_ONLY_REF_FINDER_H_