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1 /* |
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2 * Copyright (c) 2002-2003 Nokia Corporation and/or its subsidiary(-ies). |
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3 * All rights reserved. |
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4 * This component and the accompanying materials are made available |
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5 * under the terms of "Eclipse Public License v1.0" |
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6 * which accompanies this distribution, and is available |
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7 * at the URL "http://www.eclipse.org/legal/epl-v10.html". |
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8 * |
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9 * Initial Contributors: |
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10 * Nokia Corporation - initial contribution. |
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11 * |
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12 * Contributors: |
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13 * |
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14 * Description: |
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15 * |
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16 */ |
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17 |
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18 |
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19 |
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20 |
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21 // INCLUDES |
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22 |
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23 #include <e32base.h> |
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24 #include <e32std.h> |
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25 |
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26 #include "rtpstppacket.h" |
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27 |
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28 // |
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29 // RTPLite header |
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30 // |
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31 // **************************************** |
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32 // Extract from "PoC Core Network RTP RP01" |
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33 // **************************************** |
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34 // 1 2 3 |
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35 // 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 |
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36 // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
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37 // |F M R C S| PT | Sequence nbr | Checksum (optional) | |
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38 // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
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39 // |
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40 // Full header indication (F) 1 bit |
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41 // If this bit is set to zero then header format |
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42 // is reduced (otherwise full) |
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43 // |
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44 // Marker (M) 1 bit |
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45 // Indication of the start of speech item (value 1). |
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46 // It is set on the Nth first RTP packets including |
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47 // speech frames within the RTP payload. N is expected |
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48 // to have a constant value in the order of 3 to 5. |
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49 // Note: M-bit is zero for all embedded control packets. |
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50 // |
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51 // Reserved bit (R) 1 bit |
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52 // This bit is reserved for future use. Default value is 1. |
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53 // |
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54 // Checksum indication (C) 1 bit |
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55 // C-bit is an indication if header includes at the end an |
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56 // optional checksum field. Value 1 indicates that checksum |
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57 // field exist on the header. |
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58 // |
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59 // Speech Item toggle indication (S) 1 bit |
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60 // S-bit is used as an indication (toggled value) that speech |
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61 // item has been changed (toggled between two speech items |
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62 // from same source; toggled between two speech items from |
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63 // different users; toggled between two speech items from |
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64 // different groups 1-to-1 call). This bit is on the same |
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65 // position for the respective leader, speech and trailing |
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66 // packets. |
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67 // |
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68 // Payload Type (PT) 3 bits |
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69 // PT-field indicates what kind of information |
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70 // is carried on the paylaod area. Only two codes |
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71 // (000 and 001) are reserved at the first phase, |
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72 // other values are reserved for future use.000 is |
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73 // used to indicate that embedded control signal |
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74 // information is in payload area and 001 indicates |
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75 // that payload contains speech packets coded with |
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76 // IETF AMR speech coding 8. In case of embedded |
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77 // control signal coding then the first byte on the payload |
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78 // area has special coding rules, which are defined on section 5.3.4. |
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79 // Note: GSM HR (HalfRate) will be used for 1st integration testing |
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80 // and related PT is 010. |
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81 // Note: Standard RTP header uses 7 bits for the same indication. |
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82 // |
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83 // Sequence Nbr (SN) 8 bits |
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84 // The sequence nbr increments by one for each |
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85 // RTP data packet sent, and may be used by the |
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86 // receiver to detect packet loss and restore |
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87 // packet sequence. The initial value (when S |
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88 // bit is toggled) of the sequence number is zero. |
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89 // Note one exception: during talkspurt |
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90 // (for 1-to-1 call or group call) if one/few |
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91 // RTP packets are not sent (on N*20ms interval) |
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92 // due to DTX usage (silence periods not sent) |
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93 // the sequency number at the originator side |
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94 // is anyhow incremented by one with the N*20ms |
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95 // frequency. The value for N is 3 by default. |
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96 // Very probably RTP packets are always sent in |
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97 // GPRS terminals during talkspurt to avoid TBF |
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98 // drop. RTP packet payload contains during |
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99 // silence periods three NO_DATA -indication |
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100 // bytes to AMR decoder. In the future extented |
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101 // TFB timer feature may change this behaviour, |
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102 // i.e. the sending of NO_DATA -indication bytes |
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103 // might be dropped (over GPRS).Within standard |
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104 // version of RTP header the length of SN is 16 |
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105 // bits , but within PoC application it is enough |
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106 // to have 8 bits; it provides 7.62s (127*3*20ms) |
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107 // jitter buffering without any special number wrap |
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108 // control tricks (shown values are valid with N=3). |
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109 // Note: On the uplink direction on each speech item, |
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110 // the Sequency Nbr is zero for all leading packets |
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111 // (the first leading packet is replicated few times, |
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112 // but the replicated messages are identical |
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113 // (even concerning the SN field)) and the first RTP |
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114 // packet containing speech has SN value one. |
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115 // Note: for all embedded control signals the SN |
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116 // is set to zero. |
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117 // |
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118 // CheckSum (CS) 16 bits (optional) |
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119 // Checksum field is optional and the existence |
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120 // of this field is indicated on the first octet |
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121 // by C-bit. Checksum will be needed with RP01 |
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122 // interface if RLC/LLC/UDP checksums are not |
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123 // available/used. UDP checksum is optional |
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124 // with IPv4. Further more by using RTP level |
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125 // CRC in combination of UDP-lite it would be |
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126 // possible to implement more efficient unequal |
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127 // error protection on AMR bits than UDP-lite |
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128 // alone would offer.If checksum error is detected |
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129 // then whole RTP packet is discarded. |
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130 // Note: Checksum information is not available |
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131 // within standard RTP header. |
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132 // Note: Taking the other aspects (header compression |
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133 // with Degermark) into account it currently means |
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134 // that if checksum is included on RTPLite header |
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135 // the whole packet does fit to 8 kbit/s channel |
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136 // on the AIR interface only with AMR 4.75 coding. |
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137 |
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138 // ================= MEMBER FUNCTIONS ======================= |
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139 |
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140 // --------------------------------------------------------------------------- |
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141 // C++ default constructor can NOT contain any code, that |
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142 // might leave. |
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143 // --------------------------------------------------------------------------- |
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144 // |
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145 CRtpStpPacket::CRtpStpPacket() : |
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146 iSize( 0 ), |
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147 iData( 0 ), |
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148 iDataPtr( 0 ), |
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149 iSessionId( 0 ) |
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150 { |
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151 } |
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152 |
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153 // --------------------------------------------------------------------------- |
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154 // Symbian 2nd phase constructor can leave. |
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155 // --------------------------------------------------------------------------- |
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156 // |
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157 void CRtpStpPacket::ConstructL( TUint aPacketSize, TRtpId aSessionId ) |
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158 { |
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159 iBuf = HBufC8::NewL( aPacketSize ); |
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160 iData = ( TUint8* ) iBuf->Des().Ptr(); |
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161 iSize = 0; |
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162 iDataPtr = iData; |
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163 iSessionId = aSessionId; |
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164 } |
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165 |
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166 // --------------------------------------------------------------------------- |
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167 // Destructor |
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168 // --------------------------------------------------------------------------- |
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169 // |
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170 CRtpStpPacket::~CRtpStpPacket() |
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171 { |
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172 delete iBuf; |
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173 } |
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174 |
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175 // --------------------------------------------------------------------------- |
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176 // CRtpStpPacket::Close() |
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177 // works as destructor |
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178 // --------------------------------------------------------------------------- |
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179 // |
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180 void CRtpStpPacket::Close() |
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181 { |
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182 delete this; |
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183 } |
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184 |
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185 // --------------------------------------------------------------------------- |
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186 // CRtpStpPacket::RtpPacketReset() |
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187 // |
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188 // --------------------------------------------------------------------------- |
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189 // |
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190 void CRtpStpPacket::RtpPacketReset() |
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191 { |
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192 iSize = 0; |
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193 iDataPtr = iData; |
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194 } |
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195 |
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196 // --------------------------------------------------------------------------- |
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197 // CRtpStpPacket::RtpPacketResetPtr() |
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198 // |
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199 // --------------------------------------------------------------------------- |
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200 // |
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201 void CRtpStpPacket::RtpPacketResetPtr() |
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202 { |
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203 iDataPtr = iData; |
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204 } |
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205 |
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206 // --------------------------------------------------------------------------- |
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207 // TInt CRtpStpPacket::RtpPacketBuild() |
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208 // |
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209 // --------------------------------------------------------------------------- |
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210 // |
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211 TInt CRtpStpPacket::RtpPacketBuild( const TRtpSendHeader& aHeader, const TDesC8& aPayloadData ) |
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212 { |
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213 TUint8* dataP; |
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214 |
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215 dataP = iData; |
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216 |
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217 // build the packet content |
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218 Mem::FillZ( dataP, 4 ); |
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219 |
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220 // Full header indication (F) |
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221 dataP[0] |= ( 0 << 7 ); |
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222 |
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223 // Marker (M) |
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224 dataP[0] |= static_cast<TUint8>( aHeader.iMarker << 6 ); |
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225 |
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226 // Padding bit (P) = 1 |
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227 dataP[0] |= static_cast<TUint8>( aHeader.iPadding << 5 ); |
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228 |
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229 // Checksum indecation (C) if checkSumInd == 1, need checksum in the header |
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230 dataP[0] |= static_cast<TUint8>( aHeader.iChecksumInd << 4 ); |
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231 |
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232 // Speech Item toggle indication (S) |
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233 dataP[0] |= static_cast<TUint8>( aHeader.iSpeechItemToggle << 3 ); |
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234 |
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235 // payload type |
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236 dataP[0] |= ( aHeader.iPayloadType & 0x07 ); |
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237 |
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238 // sequence number |
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239 dataP[1] = aHeader.iSeqNum; |
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240 dataP += 2; |
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241 |
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242 // Optinal checksum |
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243 if ( aHeader.iChecksumInd == 1 ) |
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244 { |
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245 write16( dataP, aHeader.iChecksum ); |
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246 dataP += 2; |
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247 } |
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248 |
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249 // copy payload data |
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250 Mem::Copy( dataP, aPayloadData.Ptr(), aPayloadData.Length() ); |
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251 iSize = aPayloadData.Length() + ( dataP - iData ); |
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252 |
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253 return 0; |
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254 } |
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255 |
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256 // --------------------------------------------------------------------------- |
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257 // CRtpStpPacket::RtpPacketProcess() |
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258 // Return Value: |
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259 // KErrNone if STP packet has been processed OK, or |
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260 // KErrCorrupt if packet is invalid or some other error has occured |
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261 // --------------------------------------------------------------------------- |
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262 // |
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263 TInt CRtpStpPacket::RtpPacketProcess( TUint8* aBuf, TInt* aLength ) |
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264 { |
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265 TRtpRecvHeader header; |
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266 TUint8* dataP; |
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267 |
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268 dataP = iData; |
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269 |
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270 // Full header indication (F) |
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271 if ( ( dataP[0] & 0x80 ) != 0 ) |
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272 return KErrCorrupt; |
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273 |
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274 // Marker (M) |
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275 header.iMarker = ( TUint8 ) ( ( dataP[0] & 0x40 ) >> 6 ); |
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276 |
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277 // Padding bit (P) |
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278 header.iPadding = ( TUint8 ) ( ( dataP[0] & 0x20 ) >> 5 ); |
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279 |
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280 // Checksum indication (C) |
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281 header.iChecksumInd = ( TUint8 ) ( ( dataP[0] & 0x10 ) >> 4 ); |
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282 |
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283 // Speech item toggle indication (S) |
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284 header.iSpeechItemToggle = ( TUint8 ) ( ( dataP[0] & 0x08 ) >> 3 ); |
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285 |
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286 // Payload type (PT) |
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287 header.iPayloadType = ( TUint8 ) ( ( dataP[0] & 0x07 ) ); |
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288 |
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289 // Sequence number |
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290 header.iSeqNum = ( TUint8 ) ( dataP[1] ); |
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291 dataP += 2; |
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292 |
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293 // Optinal checksum |
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294 if ( header.iChecksumInd == 1 ) |
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295 { |
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296 header.iChecksum = ( TUint16 ) read16( dataP ); |
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297 dataP += 2; |
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298 } |
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299 |
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300 *aLength = iSize - ( dataP - iData ); |
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301 aBuf = ( TUint8 * ) dataP; |
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302 |
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303 TPtrC8 buf( aBuf, *aLength ); |
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304 |
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305 if ( iObserver ) |
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306 iObserver->RtpPacketReceived( iSessionId /* streamId */, header, buf ); |
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307 |
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308 return KErrNone; |
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309 } |
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310 |
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311 // --------------------------------------------------------------------------- |
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312 // Write a 16-bit value as 2 consecutive bytes in MSB order |
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313 // Memory (at least 2 bytes) must have been allocated to pointer |
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314 // before the function is called. |
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315 // --------------------------------------------------------------------------- |
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316 // |
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317 void CRtpStpPacket::write16( TUint8* const aPointer, TUint32 aValue ) |
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318 { |
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319 // check value range (16 bits) |
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320 aPointer[0] = ( TUint8 ) ( ( aValue & 0xFF00 ) >> 8 ); |
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321 aPointer[1] = ( TUint8 ) ( aValue & 0x00FF ); |
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322 } |
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323 |
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324 // --------------------------------------------------------------------------- |
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325 // Read a 16-bit value given as 2 consecutive bytes in MSB order |
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326 // Memory (at least 2 bytes) must have been allocated to pointer |
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327 // before the function is called. |
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328 // --------------------------------------------------------------------------- |
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329 // |
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330 TUint32 CRtpStpPacket::read16( const TUint8* const aPointer ) |
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331 { |
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332 return( aPointer[1] + ( ( TUint32 ) aPointer[0] << 8 ) ); |
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333 } |
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334 |
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335 |
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336 #if !defined ( EKA2 ) && !defined ( RTP_UNIT_TEST ) |
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337 // The E32Dll() entry point function |
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338 GLDEF_C TInt E32Dll( TDllReason /*aReason*/ ) |
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339 { |
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340 return( KErrNone ); |
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341 } |
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342 #endif // EKA2 |
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343 |
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344 // --------------------------------------------------------------------------- |
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345 // Function to construct a CRtpPacketExt object. Note that this function |
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346 // is exported at ordinal 1 and is not a member of any class. |
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347 // --------------------------------------------------------------------------- |
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348 // |
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349 EXPORT_C MRtpPacketExt* NewL() |
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350 { |
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351 return new ( ELeave ) CRtpStpPacket; |
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352 } |
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353 |
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354 |
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355 // End of File |