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      1 /*
      2  *  Copyright (c) 2015 The WebRTC project authors. All Rights Reserved.
      3  *
      4  *  Use of this source code is governed by a BSD-style license
      5  *  that can be found in the LICENSE file in the root of the source
      6  *  tree. An additional intellectual property rights grant can be found
      7  *  in the file PATENTS.  All contributing project authors may
      8  *  be found in the AUTHORS file in the root of the source tree.
      9  */
     10 
     11 #ifndef WEBRTC_MODULES_RTP_RTCP_SOURCE_RTCP_PACKET_TRANSPORT_FEEDBACK_H_
     12 #define WEBRTC_MODULES_RTP_RTCP_SOURCE_RTCP_PACKET_TRANSPORT_FEEDBACK_H_
     13 
     14 #include <deque>
     15 #include <vector>
     16 
     17 #include "webrtc/base/constructormagic.h"
     18 #include "webrtc/modules/include/module_common_types.h"
     19 #include "webrtc/modules/rtp_rtcp/source/rtcp_packet.h"
     20 
     21 namespace webrtc {
     22 namespace rtcp {
     23 
     24 class PacketStatusChunk;
     25 
     26 class TransportFeedback : public RtcpPacket {
     27  public:
     28   TransportFeedback();
     29   virtual ~TransportFeedback();
     30 
     31   void WithPacketSenderSsrc(uint32_t ssrc);
     32   void WithMediaSourceSsrc(uint32_t ssrc);
     33   void WithBase(uint16_t base_sequence,     // Seq# of first packet in this msg.
     34                 int64_t ref_timestamp_us);  // Reference timestamp for this msg.
     35   void WithFeedbackSequenceNumber(uint8_t feedback_sequence);
     36   // NOTE: This method requires increasing sequence numbers (excepting wraps).
     37   bool WithReceivedPacket(uint16_t sequence_number, int64_t timestamp_us);
     38 
     39   enum class StatusSymbol {
     40     kNotReceived,
     41     kReceivedSmallDelta,
     42     kReceivedLargeDelta,
     43   };
     44 
     45   uint16_t GetBaseSequence() const;
     46   std::vector<TransportFeedback::StatusSymbol> GetStatusVector() const;
     47   std::vector<int16_t> GetReceiveDeltas() const;
     48 
     49   // Get the reference time in microseconds, including any precision loss.
     50   int64_t GetBaseTimeUs() const;
     51   // Convenience method for getting all deltas as microseconds. The first delta
     52   // is relative the base time.
     53   std::vector<int64_t> GetReceiveDeltasUs() const;
     54 
     55   uint32_t GetPacketSenderSsrc() const;
     56   uint32_t GetMediaSourceSsrc() const;
     57   static const int kDeltaScaleFactor = 250;  // Convert to multiples of 0.25ms.
     58   static const uint8_t kFeedbackMessageType = 15;  // TODO(sprang): IANA reg?
     59   static const uint8_t kPayloadType = 205;         // RTPFB, see RFC4585.
     60 
     61   static rtc::scoped_ptr<TransportFeedback> ParseFrom(const uint8_t* buffer,
     62                                                       size_t length);
     63 
     64  protected:
     65   bool Create(uint8_t* packet,
     66               size_t* position,
     67               size_t max_length,
     68               PacketReadyCallback* callback) const override;
     69 
     70   size_t BlockLength() const override;
     71 
     72  private:
     73   static PacketStatusChunk* ParseChunk(const uint8_t* buffer, size_t max_size);
     74 
     75   int64_t Unwrap(uint16_t sequence_number);
     76   bool AddSymbol(StatusSymbol symbol, int64_t seq);
     77   bool Encode(StatusSymbol symbol);
     78   bool HandleRleCandidate(StatusSymbol symbol,
     79                           int current_capacity,
     80                           int delta_size);
     81   void EmitRemaining();
     82   void EmitVectorChunk();
     83   void EmitRunLengthChunk();
     84 
     85   uint32_t packet_sender_ssrc_;
     86   uint32_t media_source_ssrc_;
     87   int32_t base_seq_;
     88   int64_t base_time_;
     89   uint8_t feedback_seq_;
     90   std::vector<PacketStatusChunk*> status_chunks_;
     91   std::vector<int16_t> receive_deltas_;
     92 
     93   int64_t last_seq_;
     94   int64_t last_timestamp_;
     95   std::deque<StatusSymbol> symbol_vec_;
     96   uint16_t first_symbol_cardinality_;
     97   bool vec_needs_two_bit_symbols_;
     98   uint32_t size_bytes_;
     99 
    100   RTC_DISALLOW_COPY_AND_ASSIGN(TransportFeedback);
    101 };
    102 
    103 }  // namespace rtcp
    104 }  // namespace webrtc
    105 #endif  // WEBRTC_MODULES_RTP_RTCP_SOURCE_RTCP_PACKET_TRANSPORT_FEEDBACK_H_
    106