Add packetization and coding/decoding of feedback message format.

webrtc/modules/rtp_rtcp/source/rtcp_packet.h

 /*
  *  Copyright (c) 2014 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.
  *
  */
@@ skipping 74 matching lines @@
   // IP_PACKET_SIZE will be allocated and reused between calls to callback.
   bool Build(PacketReadyCallback* callback) const;
 
   // Returns true if all calls to Create succeeded. Provided buffer reference
   // will be used for all calls to callback.
   bool BuildExternalBuffer(uint8_t* buffer,
                            size_t max_length,
                            PacketReadyCallback* callback) const;
 
  protected:
-  RtcpPacket() : kHeaderLength(4) {}
+  RtcpPacket() {}
 
   virtual bool Create(uint8_t* packet,
                       size_t* index,
                       size_t max_length,
                       PacketReadyCallback* callback) const = 0;
 
+  void CreateHeader(uint8_t count_or_format,
+                    uint8_t packet_type,
+                    size_t length,
+                    uint8_t* buffer,
+                    size_t* pos) const;
+
   bool OnBufferFull(uint8_t* packet,
                     size_t* index,
                     RtcpPacket::PacketReadyCallback* callback) const;
 
-  const size_t kHeaderLength;
+  virtual size_t BlockLength() const = 0;
+  size_t HeaderLength() const;
+
+  static const size_t kHeaderLength = 4;
 
  private:
   bool CreateAndAddAppended(uint8_t* packet,
                             size_t* index,
                             size_t max_length,
                             PacketReadyCallback* callback) const;
 
   std::vector<RtcpPacket*> appended_packets_;
 };
 
+// TODO(sprang): Move RtcpPacket subclasses out to separate files.
+
 class Empty : public RtcpPacket {
  public:
   Empty() : RtcpPacket() {}
 
   virtual ~Empty() {}
 
  protected:
   bool Create(uint8_t* packet,
               size_t* index,
               size_t max_length,
               RtcpPacket::PacketReadyCallback* callback) const override;
 
+  size_t BlockLength() const override;
+
  private:
   DISALLOW_COPY_AND_ASSIGN(Empty);
 };
 
 // From RFC 3550, RTP: A Transport Protocol for Real-Time Applications.
 //
 // RTCP report block (RFC 3550).
 //
 //   0                   1                   2                   3
 //   0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
@@ skipping 505 matching lines @@
     nack_.MediaSSRC = ssrc;
   }
   void WithList(const uint16_t* nack_list, int length);
 
  protected:
   bool Create(uint8_t* packet,
               size_t* index,
               size_t max_length,
               RtcpPacket::PacketReadyCallback* callback) const override;
 
+  size_t BlockLength() const override;
+
  private:
 
   RTCPUtility::RTCPPacketRTPFBNACK nack_;
   std::vector<RTCPUtility::RTCPPacketRTPFBNACKItem> nack_fields_;
 
   DISALLOW_COPY_AND_ASSIGN(Nack);
 };
 
 // Reference picture selection indication (RPSI) (RFC 4585).
 //
@@ skipping 476 matching lines @@
 
  private:
   const size_t buffer_length_;
   size_t length_;
   rtc::scoped_ptr<uint8_t[]> buffer_;
 };
 
 }  // namespace rtcp
 }  // namespace webrtc
 #endif  // WEBRTC_MODULES_RTP_RTCP_RTCP_PACKET_H_