1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/os/mm/mmlibs/mmfw/Recogniser/src/mpeg2parser.cpp Fri Jun 15 03:10:57 2012 +0200
1.3 @@ -0,0 +1,299 @@
1.4 +// Copyright (c) 2006-2009 Nokia Corporation and/or its subsidiary(-ies).
1.5 +// All rights reserved.
1.6 +// This component and the accompanying materials are made available
1.7 +// under the terms of "Eclipse Public License v1.0"
1.8 +// which accompanies this distribution, and is available
1.9 +// at the URL "http://www.eclipse.org/legal/epl-v10.html".
1.10 +//
1.11 +// Initial Contributors:
1.12 +// Nokia Corporation - initial contribution.
1.13 +//
1.14 +// Contributors:
1.15 +//
1.16 +// Description:
1.17 +//
1.18 +
1.19 +#include "parsers.h"
1.20 +
1.21 +static const TUint8 KISOEndCode = 0xB9;
1.22 +static const TUint8 KPackStartCode = 0xBA;
1.23 +static const TUint8 KVideoElementaryStream = 0xE0;
1.24 +
1.25 +#define KMPEG1PackHeaderLen 8
1.26 +#define KMPEG2PackHeaderLen 10
1.27 +
1.28 +#define KMPEG1PackHeaderID 0x21 // 0010xxx1. See Doc Link 2.
1.29 +#define KMPEG2PackHeaderID 0x44 // 01xxx1xx. See Doc Link 2.
1.30 +
1.31 +#define KStartCodeMask 0xffffff00
1.32 +#define KStartCodeIntro 0x00000100
1.33 +
1.34 +#define KMPEG2StartCode1Bit KBit1
1.35 +#define KMPEG2StartCode2Bit KBit2
1.36 +#define KMPEG2VideoBit KBit3
1.37 +#define KMPEG2MPEG1Bit KBit4
1.38 +
1.39 +//
1.40 +// Mapping flags to a confidence level.
1.41 +//
1.42 +// A: extension match
1.43 +// B: start-code1
1.44 +// C: start-code2
1.45 +//
1.46 +// C B A -> Confidence
1.47 +// -------------------
1.48 +// 0 0 0 -> ENotRecognised
1.49 +// 0 0 1 -> EPossible
1.50 +// 0 1 0 -> EPossible
1.51 +// 0 1 1 -> EProbable
1.52 +// 1 0 0 -> ENotRecognised
1.53 +// 1 0 1 -> ENotRecognised
1.54 +// 1 1 0 -> EProbable
1.55 +// 1 1 1 -> ECertain
1.56 +//
1.57 +static const TInt KMPEG2FlagsToConfidence[] =
1.58 + {
1.59 + KConfNotRecognised,
1.60 + KConfPossible,
1.61 + KConfPossible,
1.62 + KConfProbable,
1.63 + KConfNotRecognised,
1.64 + KConfNotRecognised,
1.65 + KConfProbable,
1.66 + KConfCertain
1.67 + };
1.68 +
1.69 +#define KMPEG2ConfidenceMask 0x07 // 00000111
1.70 +#define KMPEG2MimeMask 0x18 // 00011000
1.71 +#define KMPEG2MimeShift 0x03
1.72 +
1.73 +static const TInt KMPEG2ExtOnlyIndex = 1;
1.74 +
1.75 +//
1.76 +// The 'ED' bits of the flags member are used as an index into
1.77 +// this table of possible MIME-types.
1.78 +//
1.79 +// E: MPEG1 instead of MPEG2
1.80 +// D: Video content present
1.81 +//
1.82 +// E D -> Mime
1.83 +// -----------
1.84 +// 0 0 -> audio/mpeg2
1.85 +// 0 1 -> video/mpeg2
1.86 +// 1 0 -> audio/mpeg1
1.87 +// 1 1 -> video/mpeg1
1.88 +//
1.89 +static const TText8* const KMPEG2Mimes[] =
1.90 + {
1.91 + KMimeMPEG2_A,
1.92 + KMimeMPEG2_V,
1.93 + KMimeMPEG1_A,
1.94 + KMimeMPEG1_V
1.95 + };
1.96 +
1.97 +//
1.98 +// A list of known MPEG2 file extensions.
1.99 +// MPEG1 file extensions are also listed.
1.100 +//
1.101 +typedef struct
1.102 + {
1.103 + const TText* iExt;
1.104 + const TText8* iMime;
1.105 + }
1.106 +TMPEG2Types;
1.107 +
1.108 +static const TMPEG2Types KMPEG2Types[] =
1.109 + {
1.110 + { KExtMPEG_1, KMimeMPEG2_V },
1.111 + { KExtMPEG_2, KMimeMPEG2_V },
1.112 + { KExtMPEG_3, KMimeMPEG2_V },
1.113 + { KExtMPEG_4, KMimeMPEG2_V },
1.114 + { KExtMPEG_5, KMimeMPEG2_V },
1.115 + { KExtMPEG_6, KMimeMPEG2_V },
1.116 + { KExtMPEG_7, KMimeMPEG1_V },
1.117 + { KExtMPEG_8, KMimeMPEG2_A }
1.118 + };
1.119 +
1.120 +#define KMPEG2ExtCount sizeof(KMPEG2Types) / sizeof(TMPEG2Types)
1.121 +
1.122 +
1.123 +//
1.124 +//
1.125 +//
1.126 +TMPEG2Parser::TMPEG2Parser(CReader& aReader, TFlags& aFlags)
1.127 + : iReader(aReader),
1.128 + iFlags(aFlags)
1.129 + {
1.130 + }
1.131 +
1.132 +
1.133 +//
1.134 +// Match the file's extension to known MPEG2 file extensions.
1.135 +//
1.136 +const TText8* TMPEG2Parser::MatchExtension(const TDesC& aExt)
1.137 + {
1.138 + if (aExt.Length() > 0)
1.139 + {
1.140 + for (TInt i = 0; i < KMPEG2ExtCount; i++)
1.141 + {
1.142 + if (aExt.MatchF(TPtrC(KMPEG2Types[i].iExt)) != KErrNotFound)
1.143 + {
1.144 + iFlags.SetExtensionFlag();
1.145 + return KMPEG2Types[i].iMime;
1.146 + }
1.147 + }
1.148 + }
1.149 +
1.150 + return NULL;
1.151 + }
1.152 +
1.153 +
1.154 +//
1.155 +//
1.156 +//
1.157 +void TMPEG2Parser::DoRecognise(const TDesC& aExt, CReader& aReader, TMatch& aMatch)
1.158 + {
1.159 + TFlags flags;
1.160 + TMPEG2Parser parser(aReader, flags);
1.161 +
1.162 + const TText8* extMime = parser.MatchExtension(aExt);
1.163 + TRAP_IGNORE(parser.ParseL());
1.164 +
1.165 + TInt confIndex = flags.GetBitField(KMPEG2ConfidenceMask);
1.166 + aMatch.iConfidence = KMPEG2FlagsToConfidence[confIndex];
1.167 + if (aMatch.iConfidence != KConfNotRecognised)
1.168 + {
1.169 + if (confIndex == KMPEG2ExtOnlyIndex)
1.170 + {
1.171 + // The content is corrupt, but the extension was recognised.
1.172 + aMatch.iMime = extMime;
1.173 + }
1.174 + else
1.175 + {
1.176 + TInt mimeIndex = flags.GetBitField(KMPEG2MimeMask, KMPEG2MimeShift);
1.177 + aMatch.iMime = KMPEG2Mimes[mimeIndex];
1.178 + }
1.179 + }
1.180 + }
1.181 +
1.182 +
1.183 +//
1.184 +// Attempts to parse an MPEG2 file by looking for start-codes.
1.185 +//
1.186 +void TMPEG2Parser::ParseL()
1.187 + {
1.188 + TBool finished;
1.189 +
1.190 + // Assume there's video content if we only have a buffer.
1.191 + if (iReader.Type() == CReader::EBuffer)
1.192 + {
1.193 + iFlags.SetBit(KMPEG2VideoBit);
1.194 + }
1.195 +
1.196 + do
1.197 + {
1.198 + finished = NextStartCodeL();
1.199 + }
1.200 + while (!finished);
1.201 + }
1.202 +
1.203 +
1.204 +//
1.205 +// Skips over the current start-code box.
1.206 +//
1.207 +void TMPEG2Parser::SkipL()
1.208 + {
1.209 + TUint16 size;
1.210 +
1.211 + iReader.Read16L(size);
1.212 + iReader.SeekL((TInt)size);
1.213 + }
1.214 +
1.215 +
1.216 +/*
1.217 +** Expects an MPEG2 Pack Header at the current location.
1.218 +** The Pack Header is used to determine between MPEG1 and MPEG2.
1.219 +*/
1.220 +void TMPEG2Parser::ReadPackHeaderL()
1.221 + {
1.222 + TUint8 byte;
1.223 + TBuf8<KMPEG2PackHeaderLen> header; // Size is of whichever is larger.
1.224 +
1.225 + iReader.ReadByteL(byte);
1.226 +
1.227 + if ((byte & KMPEG1PackHeaderID) == KMPEG1PackHeaderID)
1.228 + {
1.229 + iFlags.SetBit(KMPEG2MPEG1Bit);
1.230 + header.SetLength(KMPEG1PackHeaderLen - 1); // We've already read a byte.
1.231 + iReader.ReadBytesL(header);
1.232 + }
1.233 + else if ((byte & KMPEG2PackHeaderID) == KMPEG2PackHeaderID)
1.234 + {
1.235 + header.SetLength(KMPEG2PackHeaderLen - 1); // We've already read a byte.
1.236 + iReader.ReadBytesL(header);
1.237 +
1.238 + // The lowest 3 bits of the last byte say how much stuffing is present.
1.239 + TInt stuffing = header[8] & 0x07; // 00000111
1.240 + if (stuffing)
1.241 + {
1.242 + iReader.SeekL(stuffing);
1.243 + }
1.244 + }
1.245 + else
1.246 + {
1.247 + User::Leave(KErrCorrupt);
1.248 + }
1.249 +
1.250 + }
1.251 +
1.252 +//
1.253 +// Start codes are bit patterns that do not occur in the video stream.
1.254 +// The start-code sequence is expected to be at the current CReader position.
1.255 +//
1.256 +TBool TMPEG2Parser::NextStartCodeL()
1.257 + {
1.258 + TUint32 data;
1.259 +
1.260 + iReader.Read32L(data);
1.261 +
1.262 + // Start codes must begin with 0x000001ss, where 'ss' is the start code.
1.263 + if ((data & KStartCodeMask) != KStartCodeIntro)
1.264 + {
1.265 + User::Leave(KErrCorrupt);
1.266 + }
1.267 +
1.268 + if (!iFlags.GetBitField(KMPEG2StartCode1Bit))
1.269 + {
1.270 + iFlags.SetBit(KMPEG2StartCode1Bit);
1.271 + }
1.272 + else
1.273 + {
1.274 + if (!iFlags.GetBitField(KMPEG2StartCode2Bit))
1.275 + {
1.276 + iFlags.SetBit(KMPEG2StartCode2Bit);
1.277 + }
1.278 + }
1.279 +
1.280 + // Try to identify the start code.
1.281 + switch (LOW_BYTE(data))
1.282 + {
1.283 + case KPackStartCode:
1.284 + ReadPackHeaderL();
1.285 + break;
1.286 +
1.287 + case KVideoElementaryStream:
1.288 + iFlags.SetBit(KMPEG2VideoBit);
1.289 + return ETrue;
1.290 +
1.291 + case KISOEndCode:
1.292 + // This code should occur at the end of the file and
1.293 + // it cannot be skipped over.
1.294 + return ETrue;
1.295 +
1.296 + default:
1.297 + SkipL();
1.298 + }
1.299 +
1.300 + return EFalse;
1.301 + }
1.302 +