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      1 /*
      2  *  Copyright (c) 2012 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_RTP_UTILITY_H_
     12 #define WEBRTC_MODULES_RTP_RTCP_SOURCE_RTP_UTILITY_H_
     13 
     14 #include <stddef.h> // size_t, ptrdiff_t
     15 
     16 #include "webrtc/modules/rtp_rtcp/interface/rtp_rtcp_defines.h"
     17 #include "webrtc/modules/rtp_rtcp/interface/receive_statistics.h"
     18 #include "webrtc/modules/rtp_rtcp/source/rtp_header_extension.h"
     19 #include "webrtc/modules/rtp_rtcp/source/rtp_rtcp_config.h"
     20 #include "webrtc/typedefs.h"
     21 
     22 namespace webrtc {
     23 
     24 const uint8_t kRtpMarkerBitMask = 0x80;
     25 
     26 RtpData* NullObjectRtpData();
     27 RtpFeedback* NullObjectRtpFeedback();
     28 RtpAudioFeedback* NullObjectRtpAudioFeedback();
     29 ReceiveStatistics* NullObjectReceiveStatistics();
     30 
     31 namespace RtpUtility {
     32     // January 1970, in NTP seconds.
     33     const uint32_t NTP_JAN_1970 = 2208988800UL;
     34 
     35     // Magic NTP fractional unit.
     36     const double NTP_FRAC = 4.294967296E+9;
     37 
     38     struct Payload
     39     {
     40         char name[RTP_PAYLOAD_NAME_SIZE];
     41         bool audio;
     42         PayloadUnion typeSpecific;
     43     };
     44 
     45     typedef std::map<int8_t, Payload*> PayloadTypeMap;
     46 
     47     // Return the current RTP timestamp from the NTP timestamp
     48     // returned by the specified clock.
     49     uint32_t GetCurrentRTP(Clock* clock, uint32_t freq);
     50 
     51     // Return the current RTP absolute timestamp.
     52     uint32_t ConvertNTPTimeToRTP(uint32_t NTPsec,
     53                                  uint32_t NTPfrac,
     54                                  uint32_t freq);
     55 
     56     uint32_t pow2(uint8_t exp);
     57 
     58     // Returns true if |newTimestamp| is older than |existingTimestamp|.
     59     // |wrapped| will be set to true if there has been a wraparound between the
     60     // two timestamps.
     61     bool OldTimestamp(uint32_t newTimestamp,
     62                       uint32_t existingTimestamp,
     63                       bool* wrapped);
     64 
     65     bool StringCompare(const char* str1,
     66                        const char* str2,
     67                        const uint32_t length);
     68 
     69     void AssignUWord32ToBuffer(uint8_t* dataBuffer, uint32_t value);
     70     void AssignUWord24ToBuffer(uint8_t* dataBuffer, uint32_t value);
     71     void AssignUWord16ToBuffer(uint8_t* dataBuffer, uint16_t value);
     72 
     73     /**
     74      * Converts a network-ordered two-byte input buffer to a host-ordered value.
     75      * \param[in] dataBuffer Network-ordered two-byte buffer to convert.
     76      * \return Host-ordered value.
     77      */
     78     uint16_t BufferToUWord16(const uint8_t* dataBuffer);
     79 
     80     /**
     81      * Converts a network-ordered three-byte input buffer to a host-ordered value.
     82      * \param[in] dataBuffer Network-ordered three-byte buffer to convert.
     83      * \return Host-ordered value.
     84      */
     85     uint32_t BufferToUWord24(const uint8_t* dataBuffer);
     86 
     87     /**
     88      * Converts a network-ordered four-byte input buffer to a host-ordered value.
     89      * \param[in] dataBuffer Network-ordered four-byte buffer to convert.
     90      * \return Host-ordered value.
     91      */
     92     uint32_t BufferToUWord32(const uint8_t* dataBuffer);
     93 
     94     class RtpHeaderParser {
     95     public:
     96      RtpHeaderParser(const uint8_t* rtpData, size_t rtpDataLength);
     97      ~RtpHeaderParser();
     98 
     99         bool RTCP() const;
    100         bool ParseRtcp(RTPHeader* header) const;
    101         bool Parse(RTPHeader& parsedPacket,
    102                    RtpHeaderExtensionMap* ptrExtensionMap = NULL) const;
    103 
    104     private:
    105         void ParseOneByteExtensionHeader(
    106             RTPHeader& parsedPacket,
    107             const RtpHeaderExtensionMap* ptrExtensionMap,
    108             const uint8_t* ptrRTPDataExtensionEnd,
    109             const uint8_t* ptr) const;
    110 
    111         uint8_t ParsePaddingBytes(
    112             const uint8_t* ptrRTPDataExtensionEnd,
    113             const uint8_t* ptr) const;
    114 
    115         const uint8_t* const _ptrRTPDataBegin;
    116         const uint8_t* const _ptrRTPDataEnd;
    117     };
    118 }  // namespace RtpUtility
    119 }  // namespace webrtc
    120 
    121 #endif // WEBRTC_MODULES_RTP_RTCP_SOURCE_RTP_UTILITY_H_
    122