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1 // Copyright (c) 2006-2009 Nokia Corporation and/or its subsidiary(-ies). |
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2 // All rights reserved. |
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3 // This component and the accompanying materials are made available |
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4 // under the terms of "Eclipse Public License v1.0" |
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5 // which accompanies this distribution, and is available |
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6 // at the URL "http://www.eclipse.org/legal/epl-v10.html". |
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7 // |
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8 // Initial Contributors: |
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9 // Nokia Corporation - initial contribution. |
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10 // |
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11 // Contributors: |
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12 // |
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13 // Description: |
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14 // |
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15 |
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16 #include "parsers.h" |
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17 |
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18 static const TUint32 KRMFileHeaderId = MAKE_INT32('.', 'R', 'M', 'F'); |
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19 static const TUint32 KRMMediaPropertiesId = MAKE_INT32('M', 'D', 'P', 'R'); |
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20 static const TInt KRMMaxMimeTypeLen = 255; // Specified by an 8-bit field |
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21 |
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22 #define KRMExtensionBit KBit0 |
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23 #define KRMFileHeaderBit KBit1 |
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24 #define KRMMediaPropertiesBit KBit2 |
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25 #define KRMVideoBit KBit3 |
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26 |
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27 #define KRMVideoMask 0x08 // 0000 1000 |
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28 #define KRMConfidenceMask 0x07 // 0000 0111 |
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29 |
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30 // |
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31 // This truth table maps the following flags to a confidence level. |
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32 // ----------------------------------------------------------------- |
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33 // A: MediaProperties chunk found |
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34 // B: FileHeader signature found |
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35 // C: Extension recognised. |
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36 // |
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37 // A B C -> Confidence |
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38 // =================== |
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39 // 0 0 0 -> ENotRecognized |
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40 // 0 0 1 -> EPossible |
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41 // 0 1 0 -> EPossible (EPossible beacuse the header is ASCII and may match plaintext) |
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42 // 0 1 1 -> ECertain |
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43 // 1 0 0 -> ENotRecognised (Can't have MediaProperties without FileHeader) |
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44 // 1 0 1 -> ENotRecognised (Can't have MediaProperties without FileHeader) |
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45 // 1 1 0 -> EProbable |
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46 // 1 1 1 -> ECertain |
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47 // |
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48 static const TInt KRMFlagsToConfidence[] = |
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49 { |
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50 KConfNotRecognised, |
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51 KConfPossible, |
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52 KConfPossible, |
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53 KConfCertain, |
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54 KConfNotRecognised, |
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55 KConfNotRecognised, |
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56 KConfProbable, |
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57 KConfCertain |
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58 }; |
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59 |
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60 |
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61 // |
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62 // Constructor. |
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63 // |
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64 TRMParser::TRMParser(CReader& aReader, TFlags& aFlags) |
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65 : iReader(aReader), |
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66 iFlags(aFlags) |
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67 { |
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68 } |
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69 |
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70 |
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71 // |
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72 // The main RealMedia parsing function. |
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73 // |
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74 void TRMParser::DoRecognise(const TDesC& aFileExt, CReader& aReader, TMatch& aMatch) |
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75 { |
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76 TFlags flags; |
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77 TRMParser parser(aReader, flags); |
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78 |
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79 parser.MatchExtension(aFileExt); |
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80 |
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81 TRAP_IGNORE(parser.ParseL()); |
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82 |
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83 TInt confIndex = flags.GetBitField(KRMConfidenceMask); |
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84 aMatch.iConfidence = KRMFlagsToConfidence[confIndex]; |
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85 |
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86 if (aMatch.iConfidence != KConfNotRecognised) |
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87 { |
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88 aMatch.iMime = (flags.GetBitField(KRMVideoMask) ? KMimeRM_V : KMimeRM_A); |
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89 } |
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90 } |
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91 |
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92 |
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93 // |
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94 // Match the file extension given by AppArc against known |
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95 // extensions for this format. |
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96 // |
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97 void TRMParser::MatchExtension(const TDesC& aFileExt) |
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98 { |
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99 TBool match; |
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100 |
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101 match = (aFileExt.MatchF(TPtrC(KExtRMF)) != KErrNotFound); |
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102 match |= (aFileExt.MatchF(TPtrC(KExtRM)) != KErrNotFound); |
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103 |
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104 if (match) |
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105 { |
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106 iFlags.SetExtensionFlag(); |
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107 } |
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108 } |
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109 |
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110 // |
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111 // RealMedia files are divided into chunks. Chunks begins with a 32-bit identifier |
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112 // which is followed by a 32-bit unsigned field that specifies the size of the chunk |
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113 // in bytes. Since the size field is unsigned, it must be cast to a TInt64 in order |
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114 // for SeekL() to work reliably. The size field also includes the length of the chunk |
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115 // identifier and the length of the size field itself, so these must be subtracted |
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116 // from any seek operation. |
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117 // |
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118 void TRMParser::ParseL() |
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119 { |
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120 TUint32 objectId; |
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121 TUint32 size; |
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122 const TInt KChunkHeaderSize = sizeof(TUint32) * 2; // sizeof objectId and size fields. |
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123 |
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124 // The first chunk must be the FileHeader. |
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125 ReadChunkHeaderL(objectId, size, ETrue); |
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126 |
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127 // Assume there's video content if we only have buffer data. |
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128 if (iReader.Type() == CReader::EBuffer) |
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129 { |
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130 iFlags.SetBit(KRMVideoBit); |
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131 } |
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132 |
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133 iReader.SeekL(TInt64(size - KChunkHeaderSize)); |
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134 |
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135 // The other chunks can occur in any order. |
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136 TBool complete = EFalse; |
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137 do |
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138 { |
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139 ReadChunkHeaderL(objectId, size); |
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140 |
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141 if (objectId == KRMMediaPropertiesId) |
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142 { |
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143 iFlags.SetBit(KRMMediaPropertiesBit); |
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144 if (ReadMediaPropertiesL()) |
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145 { |
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146 // Exit early if the video flag has been set by ReadMediaPropertiesL. |
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147 complete = ETrue; |
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148 } |
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149 } |
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150 else |
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151 { |
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152 // Skip over the unneeded chunk. |
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153 iReader.SeekL(TInt64(size - KChunkHeaderSize)); |
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154 } |
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155 } |
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156 while (!complete); |
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157 } |
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158 |
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159 |
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160 // |
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161 // Reads the chunk identifier and size. |
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162 // |
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163 void TRMParser::ReadChunkHeaderL(TUint32& aObjectId, TUint32& aSize, TBool aFirstChunk) |
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164 { |
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165 iReader.Read32L(aObjectId); |
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166 |
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167 if (aFirstChunk) |
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168 { |
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169 if (aObjectId == KRMFileHeaderId) |
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170 { |
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171 iFlags.SetBit(KRMFileHeaderBit); |
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172 } |
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173 else |
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174 { |
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175 User::Leave(KErrCorrupt); |
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176 } |
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177 } |
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178 |
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179 iReader.Read32L(aSize); |
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180 if (aSize == 0) |
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181 { |
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182 User::Leave(KErrCorrupt); |
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183 } |
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184 } |
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185 |
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186 |
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187 // |
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188 // The MediaProperties chunk describes a stream in the RM file. There |
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189 // may be several MediaProperties chunks in one file. In order to determine |
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190 // if video content is present we must look at the MIME-type that may |
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191 // be present in each MediaProperties chunk. |
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192 // Return ETrue if this function set the video bit. |
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193 // |
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194 TBool TRMParser::ReadMediaPropertiesL() |
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195 { |
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196 const TInt KBytesToFieldSize = 30; |
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197 |
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198 // ObjectId and size fields have already been read. |
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199 TBool setVideo = EFalse; |
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200 TUint16 objectVersion; |
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201 |
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202 iReader.Read16L(objectVersion); |
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203 |
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204 if (objectVersion == 0) |
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205 { |
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206 TUint8 fieldSize; |
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207 TBuf8<KRMMaxMimeTypeLen> mimeType; |
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208 _LIT8(KVideoStar, "video/*"); |
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209 |
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210 // Skip unneeded information. |
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211 iReader.SeekL(KBytesToFieldSize); |
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212 |
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213 // Read stream_name_size so we can skip over it. |
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214 iReader.ReadByteL(fieldSize); |
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215 iReader.SeekL(fieldSize); |
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216 |
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217 // Read the mime_type_size. Because it's 8-bit, it has a max length of 256 bytes. |
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218 iReader.ReadByteL(fieldSize); |
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219 |
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220 mimeType.SetLength(fieldSize); |
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221 iReader.ReadBytesL(mimeType); |
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222 |
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223 // Now check if the mime-type field indicates video content. |
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224 if (mimeType.MatchF(KVideoStar) != KErrNotFound) |
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225 { |
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226 iFlags.SetBit(KRMVideoBit); |
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227 setVideo = ETrue; |
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228 } |
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229 |
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230 // Read the type_specific_len so we can skip over it. |
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231 TUint32 typeSpecificLen; |
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232 iReader.Read32L(typeSpecificLen); |
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233 iReader.SeekL(TInt64(typeSpecificLen)); |
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234 } |
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235 |
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236 return setVideo; |
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237 } |
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238 |