sl@0: // Copyright (c) 2006-2009 Nokia Corporation and/or its subsidiary(-ies).
sl@0: // All rights reserved.
sl@0: // This component and the accompanying materials are made available
sl@0: // under the terms of "Eclipse Public License v1.0"
sl@0: // which accompanies this distribution, and is available
sl@0: // at the URL "http://www.eclipse.org/legal/epl-v10.html".
sl@0: //
sl@0: // Initial Contributors:
sl@0: // Nokia Corporation - initial contribution.
sl@0: //
sl@0: // Contributors:
sl@0: //
sl@0: // Description:
sl@0: //
sl@0: 
sl@0: #include "parsers.h"
sl@0: 
sl@0: static const TUint8 KISOEndCode = 0xB9;
sl@0: static const TUint8 KPackStartCode = 0xBA;
sl@0: static const TUint8 KVideoElementaryStream = 0xE0;
sl@0: 
sl@0: #define KMPEG1PackHeaderLen		8
sl@0: #define KMPEG2PackHeaderLen		10
sl@0: 
sl@0: #define KMPEG1PackHeaderID		0x21	// 0010xxx1. See Doc Link 2.
sl@0: #define KMPEG2PackHeaderID		0x44	// 01xxx1xx. See Doc Link 2.
sl@0: 
sl@0: #define KStartCodeMask			0xffffff00
sl@0: #define KStartCodeIntro			0x00000100
sl@0: 
sl@0: #define KMPEG2StartCode1Bit	KBit1
sl@0: #define KMPEG2StartCode2Bit	KBit2
sl@0: #define KMPEG2VideoBit		KBit3
sl@0: #define KMPEG2MPEG1Bit		KBit4
sl@0: 
sl@0: //
sl@0: // Mapping flags to a confidence level.
sl@0: //
sl@0: // A: extension match
sl@0: // B: start-code1
sl@0: // C: start-code2
sl@0: //
sl@0: // C B A -> Confidence
sl@0: // -------------------
sl@0: // 0 0 0 -> ENotRecognised
sl@0: // 0 0 1 -> EPossible
sl@0: // 0 1 0 -> EPossible
sl@0: // 0 1 1 -> EProbable
sl@0: // 1 0 0 -> ENotRecognised
sl@0: // 1 0 1 -> ENotRecognised
sl@0: // 1 1 0 -> EProbable
sl@0: // 1 1 1 -> ECertain
sl@0: //
sl@0: static const TInt KMPEG2FlagsToConfidence[] =
sl@0: 	{
sl@0: 	KConfNotRecognised,
sl@0: 	KConfPossible,
sl@0: 	KConfPossible,
sl@0: 	KConfProbable,
sl@0: 	KConfNotRecognised,
sl@0: 	KConfNotRecognised,
sl@0: 	KConfProbable,
sl@0: 	KConfCertain
sl@0: 	};
sl@0: 
sl@0: #define KMPEG2ConfidenceMask	0x07	// 00000111
sl@0: #define KMPEG2MimeMask	 		0x18	// 00011000
sl@0: #define KMPEG2MimeShift			0x03	
sl@0: 
sl@0: static const TInt KMPEG2ExtOnlyIndex = 1;
sl@0: 	
sl@0: //
sl@0: // The 'ED' bits of the flags member are used as an index into
sl@0: // this table of possible MIME-types.
sl@0: //
sl@0: // E: MPEG1 instead of MPEG2
sl@0: // D: Video content present
sl@0: //
sl@0: // E D -> Mime
sl@0: // -----------
sl@0: // 0 0 -> audio/mpeg2
sl@0: // 0 1 -> video/mpeg2
sl@0: // 1 0 -> audio/mpeg1
sl@0: // 1 1 -> video/mpeg1
sl@0: //
sl@0: static const TText8* const KMPEG2Mimes[] = 
sl@0: 	{
sl@0: 	KMimeMPEG2_A,
sl@0: 	KMimeMPEG2_V,
sl@0: 	KMimeMPEG1_A,
sl@0: 	KMimeMPEG1_V
sl@0: 	};
sl@0: 
sl@0: //
sl@0: // A list of known MPEG2 file extensions.
sl@0: // MPEG1 file extensions are also listed.
sl@0: //
sl@0: typedef struct
sl@0: 	{
sl@0: 	const TText* iExt;
sl@0: 	const TText8* iMime;
sl@0: 	}
sl@0: TMPEG2Types;
sl@0: 
sl@0: static const TMPEG2Types KMPEG2Types[] = 
sl@0: 	{
sl@0: 		{ KExtMPEG_1, KMimeMPEG2_V },
sl@0: 		{ KExtMPEG_2, KMimeMPEG2_V },
sl@0: 		{ KExtMPEG_3, KMimeMPEG2_V },
sl@0: 		{ KExtMPEG_4, KMimeMPEG2_V },
sl@0: 		{ KExtMPEG_5, KMimeMPEG2_V },
sl@0: 		{ KExtMPEG_6, KMimeMPEG2_V },
sl@0: 		{ KExtMPEG_7, KMimeMPEG1_V },
sl@0: 		{ KExtMPEG_8, KMimeMPEG2_A }
sl@0: 	};
sl@0: 	
sl@0: #define KMPEG2ExtCount sizeof(KMPEG2Types) / sizeof(TMPEG2Types)
sl@0: 	
sl@0: 
sl@0: //
sl@0: //
sl@0: //
sl@0: TMPEG2Parser::TMPEG2Parser(CReader& aReader, TFlags& aFlags)
sl@0:  :	iReader(aReader),
sl@0:  	iFlags(aFlags)
sl@0: 	{
sl@0: 	}
sl@0: 
sl@0: 
sl@0: //
sl@0: // Match the file's extension to known MPEG2 file extensions.
sl@0: //
sl@0: const TText8* TMPEG2Parser::MatchExtension(const TDesC& aExt)
sl@0: 	{
sl@0: 	if (aExt.Length() > 0)
sl@0: 		{
sl@0: 		for (TInt i = 0; i < KMPEG2ExtCount; i++)
sl@0: 			{
sl@0: 			if (aExt.MatchF(TPtrC(KMPEG2Types[i].iExt)) != KErrNotFound)
sl@0: 				{
sl@0: 				iFlags.SetExtensionFlag();
sl@0: 				return KMPEG2Types[i].iMime;
sl@0: 				}
sl@0: 			}
sl@0: 		}
sl@0: 	
sl@0: 	return NULL;
sl@0: 	}
sl@0: 
sl@0: 
sl@0: //
sl@0: //
sl@0: //
sl@0: void TMPEG2Parser::DoRecognise(const TDesC& aExt, CReader& aReader, TMatch& aMatch)
sl@0: 	{
sl@0: 	TFlags flags;
sl@0: 	TMPEG2Parser parser(aReader, flags);
sl@0: 	
sl@0: 	const TText8* extMime = parser.MatchExtension(aExt);
sl@0: 	TRAP_IGNORE(parser.ParseL());
sl@0: 	
sl@0: 	TInt confIndex = flags.GetBitField(KMPEG2ConfidenceMask);
sl@0: 	aMatch.iConfidence = KMPEG2FlagsToConfidence[confIndex];
sl@0: 	if (aMatch.iConfidence != KConfNotRecognised)
sl@0: 		{
sl@0: 		if (confIndex == KMPEG2ExtOnlyIndex)
sl@0: 			{
sl@0: 			// The content is corrupt, but the extension was recognised.
sl@0: 			aMatch.iMime = extMime;
sl@0: 			}
sl@0: 		else
sl@0: 			{
sl@0: 			TInt mimeIndex = flags.GetBitField(KMPEG2MimeMask, KMPEG2MimeShift);
sl@0: 			aMatch.iMime = KMPEG2Mimes[mimeIndex];
sl@0: 			}
sl@0: 		}
sl@0: 	}
sl@0: 
sl@0: 
sl@0: //
sl@0: // Attempts to parse an MPEG2 file by looking for start-codes.
sl@0: //
sl@0: void TMPEG2Parser::ParseL()
sl@0: 	{
sl@0: 	TBool finished;
sl@0: 	
sl@0: 	// Assume there's video content if we only have a buffer.
sl@0: 	if (iReader.Type() == CReader::EBuffer)
sl@0: 		{
sl@0: 		iFlags.SetBit(KMPEG2VideoBit);
sl@0: 		}
sl@0: 	
sl@0: 	do
sl@0: 		{
sl@0: 		finished = NextStartCodeL();
sl@0: 		}
sl@0: 	while (!finished);
sl@0: 	}
sl@0: 
sl@0: 
sl@0: //
sl@0: // Skips over the current start-code box.
sl@0: //
sl@0: void TMPEG2Parser::SkipL()
sl@0: 	{
sl@0: 	TUint16 size;
sl@0: 	
sl@0: 	iReader.Read16L(size);
sl@0: 	iReader.SeekL((TInt)size);
sl@0: 	}
sl@0: 
sl@0: 
sl@0: /*
sl@0: ** Expects an MPEG2 Pack Header at the current location.
sl@0: ** The Pack Header is used to determine between MPEG1 and MPEG2.
sl@0: */
sl@0: void TMPEG2Parser::ReadPackHeaderL()
sl@0: 	{
sl@0: 	TUint8 byte;
sl@0: 	TBuf8<KMPEG2PackHeaderLen> header;	// Size is of whichever is larger.
sl@0: 	
sl@0: 	iReader.ReadByteL(byte);
sl@0: 	
sl@0: 	if ((byte & KMPEG1PackHeaderID) == KMPEG1PackHeaderID)
sl@0: 		{
sl@0: 		iFlags.SetBit(KMPEG2MPEG1Bit);
sl@0: 		header.SetLength(KMPEG1PackHeaderLen - 1);	// We've already read a byte.
sl@0: 		iReader.ReadBytesL(header);
sl@0: 		}
sl@0: 	else if ((byte & KMPEG2PackHeaderID) == KMPEG2PackHeaderID)
sl@0: 		{
sl@0: 		header.SetLength(KMPEG2PackHeaderLen - 1);	// We've already read a byte.
sl@0: 		iReader.ReadBytesL(header);
sl@0: 		
sl@0: 		// The lowest 3 bits of the last byte say how much stuffing is present.
sl@0: 		TInt stuffing = header[8] & 0x07; // 00000111
sl@0: 		if (stuffing)
sl@0: 			{
sl@0: 			iReader.SeekL(stuffing);
sl@0: 			}
sl@0: 		}
sl@0: 	else
sl@0: 		{
sl@0: 		User::Leave(KErrCorrupt);
sl@0: 		}
sl@0: 		
sl@0: 	}
sl@0: 
sl@0: //
sl@0: // Start codes are bit patterns that do not occur in the video stream.
sl@0: // The start-code sequence is expected to be at the current CReader position.
sl@0: //
sl@0: TBool TMPEG2Parser::NextStartCodeL()
sl@0: 	{
sl@0: 	TUint32 data;
sl@0: 
sl@0: 	iReader.Read32L(data);
sl@0: 	
sl@0: 	// Start codes must begin with 0x000001ss, where 'ss' is the start code.
sl@0: 	if ((data & KStartCodeMask) != KStartCodeIntro)
sl@0: 		{
sl@0: 		User::Leave(KErrCorrupt);
sl@0: 		}
sl@0: 		
sl@0: 	if (!iFlags.GetBitField(KMPEG2StartCode1Bit))
sl@0: 		{
sl@0: 		iFlags.SetBit(KMPEG2StartCode1Bit);
sl@0: 		}
sl@0: 	else
sl@0: 		{
sl@0: 		if (!iFlags.GetBitField(KMPEG2StartCode2Bit))
sl@0: 			{
sl@0: 			iFlags.SetBit(KMPEG2StartCode2Bit);
sl@0: 			}
sl@0: 		}
sl@0: 		
sl@0: 	// Try to identify the start code.
sl@0: 	switch (LOW_BYTE(data))
sl@0: 		{
sl@0: 		case KPackStartCode:
sl@0: 			ReadPackHeaderL();
sl@0: 			break;
sl@0: 			
sl@0: 		case KVideoElementaryStream:
sl@0: 			iFlags.SetBit(KMPEG2VideoBit);
sl@0: 			return ETrue;
sl@0: 			
sl@0: 		case KISOEndCode:
sl@0: 			// This code should occur at the end of the file and
sl@0: 			// it cannot be skipped over.
sl@0: 			return ETrue;
sl@0: 			
sl@0: 		default:
sl@0: 			SkipL();
sl@0: 		}
sl@0: 		
sl@0: 	return EFalse;
sl@0: 	}
sl@0: