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: 
sl@0: #include "parsers.h"
sl@0: 
sl@0: //
sl@0: // Masks used for reading bits.
sl@0: //
sl@0: static const TInt KMP3Sync1Mask = 0xff;			// 11111111
sl@0: static const TInt KMP3Sync2Mask = 0xe0;			// 11100000
sl@0: static const TInt KMP3VersionMask = 0x18;		// 00011000
sl@0: static const TInt KMP3LayerMask = 0x06;			// 00000110
sl@0: static const TInt KMP3BitrateMask = 0xf0;		// 11110000
sl@0: static const TInt KMP3SampleRateMask = 0x0c;	// 00001100
sl@0: static const TInt KMP3PaddingMask = 0x02;		// 00000010
sl@0: 
sl@0: static const TInt KBitsPerByte = 8;
sl@0: 
sl@0: //
sl@0: // Macros for retrieving the values.
sl@0: //
sl@0: #define MP3_GET_SYNC1(d)				(d & KMP3Sync1Mask)
sl@0: #define MP3_GET_SYNC2(d)				((d & KMP3Sync2Mask) >> 5)
sl@0: #define MP3_GET_VERSION(d)				((d & KMP3VersionMask) >> 3)
sl@0: #define MP3_GET_LAYER(d)				((d & KMP3LayerMask) >> 1)
sl@0: #define MP3_GET_BITRATE(d)				((d & KMP3BitrateMask) >> 4)
sl@0: #define MP3_GET_SAMPLE_RATE(d)			((d & KMP3SampleRateMask) >> 2)
sl@0: #define MP3_GET_PADDING(d)				((d & KMP3PaddingMask) >> 1)
sl@0: 
sl@0: 
sl@0: //
sl@0: // Macros used for checking various bitfields.
sl@0: //
sl@0: #define IS_BAD_MP3_FRAME_SYNC1(s)		((s) != 0xff)
sl@0: #define IS_BAD_MP3_FRAME_SYNC2(s)		((s) != 0x07)	
sl@0: #define IS_BAD_MP3_VERSION(v)			((v) <  0x02)
sl@0: #define IS_BAD_MP3_LAYER(l)				((l) == 0x00) 
sl@0: #define IS_BAD_MP3_BITRATE(b)			((b) == 0x0f)	
sl@0: #define IS_BAD_MP3_SAMPLE_RATE(s)		((s) == 0x03)
sl@0: 
sl@0: 
sl@0: // 
sl@0: // Meanings of the 'Version' field.
sl@0: // --------------------------------
sl@0: // 00 - MPEG Version 2.5 (Unofficial standard. We don't support it.)
sl@0: // 01 - Reserved
sl@0: // 10 - MPEG Version 2
sl@0: // 11 - MPEG Version 1
sl@0: //
sl@0: static const TInt8 KMP3Version2 = 2;
sl@0: static const TInt8 KMP3Version1 = 3;
sl@0: 
sl@0: 
sl@0: // 
sl@0: // Meanings of the 'Layer' field.
sl@0: // ------------------------------
sl@0: // 00 - Reserved
sl@0: // 01 - Layer III
sl@0: // 10 - Layer II
sl@0: // 11 - Layer I
sl@0: //
sl@0: 
sl@0: static const TUint16 KBad = 0;
sl@0: static const TUint16 KFree = 0;
sl@0: 
sl@0: //
sl@0: // MPEG Version 1 bitrates. Measured in kilobits per second.
sl@0: //
sl@0: static const TUint16 KBitrateVersion1[4][16] =
sl@0: 	{
sl@0: 	{ KBad, KBad, KBad, KBad, KBad, KBad, KBad, KBad, KBad, KBad, KBad, KBad, KBad, KBad, KBad, KBad}, // Reserved layer
sl@0: 	{KFree,   32,   40,   48,   56,   64,   80,   96,  112,  128,  160,  192,  224,  256,  320, KBad}, // Layer III
sl@0: 	{KFree,   32,   48,   56,   64,   80,   96,  112,  128,  160,  192,  224,  256,  320,  384, KBad}, // Layer II
sl@0: 	{KFree,   32,   64,   96,  128,  160,  192,  224,  256,  288,  320,  352,  384,  416,  448, KBad}  // Layer I
sl@0: 	};
sl@0: 
sl@0: //
sl@0: // MPEG Version 2 bitrates. Measured in kilobits per second.
sl@0: //
sl@0: static const TUint16 KBitrateVersion2[4][16] =
sl@0: 	{
sl@0: 	{ KBad, KBad, KBad, KBad, KBad, KBad, KBad, KBad, KBad, KBad, KBad, KBad, KBad, KBad, KBad, KBad}, // Reserved layer
sl@0: 	{KFree,    8,   16,   24,   32,   40,   48,   56,   64,   80,   96,  112,  128,  144,  160, KBad}, // Layer III 
sl@0: 	{KFree,    8,   16,   24,   32,   40,   48,   56,   64,   80,   96,  112,  128,  144,  160, KBad}, // Layer II
sl@0: 	{KFree,   32,   48,   56,   64,   80,   96,  112,  128,  144,  160,  176,  192,  224,  256, KBad}  // Layer I
sl@0: 	};
sl@0: 
sl@0: //
sl@0: // Sample rates for the MPEG versions.
sl@0: //
sl@0: static const TUint16 KSampleRate[4][4] = 
sl@0: 	{
sl@0: 		{11025, 12000,  8000, KBad}, // Version 2.5
sl@0: 		{ KBad,  KBad,  KBad, KBad}, // Reserved
sl@0: 		{22050, 24000, 16000, KBad}, // Version 2
sl@0: 		{44100, 48000, 32000, KBad}  // Version 1
sl@0: 	};
sl@0: 
sl@0: //
sl@0: // Sample rates per frame for the MPEG layers.
sl@0: //
sl@0: static const TUint16 KSamplesPerFrame[4][4] = 
sl@0: 	{
sl@0: 		{KBad, KBad, KBad, KBad}, // Reserved layer
sl@0: 		{ 576, KBad,  576, 1152}, // Layer III
sl@0: 		{1152, KBad, 1152, 1152}, // Layer II
sl@0: 		{ 384, KBad,  384,  384}  // Layer I
sl@0: 	};
sl@0: 
sl@0: //
sl@0: // The various states the recognition process goes through.
sl@0: //
sl@0: typedef enum
sl@0: 	{
sl@0: 	ESearchFrame1,
sl@0: 	ESearchFrame2
sl@0: 	}
sl@0: TMP3State;
sl@0: 
sl@0: //
sl@0: // This truth table maps the following flags to a confidence level.
sl@0: // -----------------------------------------------------------------
sl@0: // A: Frame2 found.
sl@0: // B: Frame1 found.
sl@0: // C: Extension recognised.
sl@0: //
sl@0: // A B C -> Confidence
sl@0: // ===================
sl@0: // 0 0 0 -> ENotRecognized
sl@0: // 0 0 1 -> EPossible
sl@0: // 0 1 0 -> ENotRecognized
sl@0: // 0 1 1 -> ECertain
sl@0: // 1 0 0 -> EPossible
sl@0: // 1 0 1 -> EProbable
sl@0: // 1 1 0 -> EProbable
sl@0: // 1 1 1 -> ECertain
sl@0: //
sl@0: // In the case where two consecutive mp3 frames
sl@0: // are found, ECertain is automatically returned.
sl@0: //
sl@0: static const TInt KMP3FlagsToConfidence[8] = 
sl@0: 	{
sl@0: 	KConfNotRecognised,
sl@0: 	KConfPossible,
sl@0: 	KConfNotRecognised,
sl@0: 	KConfCertain,
sl@0: 	KConfPossible,
sl@0: 	KConfProbable,
sl@0: 	KConfProbable,
sl@0: 	KConfCertain
sl@0: 	};
sl@0: 
sl@0: #define KMP3ConfidenceMask	0x07	// 00000111
sl@0: #define KMP3Frame1Bit		KBit1
sl@0: #define KMP3Frame2Bit		KBit2
sl@0: 
sl@0: //
sl@0: //
sl@0: //
sl@0: TMP3Parser::TMP3Parser(CReader& aReader, TFlags& aFlags)
sl@0:  : 	iReader(aReader),
sl@0:  	iFlags(aFlags)
sl@0: 	{
sl@0: 	}
sl@0: 
sl@0: 
sl@0: //
sl@0: // MP3 recogition function.
sl@0: //
sl@0: void TMP3Parser::DoRecognise(const TDesC& aExt, CReader& aReader, TMatch& aMatch)
sl@0: 	{
sl@0: 	TFlags flags;
sl@0: 	
sl@0: 	// Try to match the extension.
sl@0: 	if (aExt.MatchF(TPtrC(KExtMP3)) != KErrNotFound)
sl@0: 		{
sl@0: 		flags.SetExtensionFlag();
sl@0: 		}
sl@0: 
sl@0: 	// Parse the data.
sl@0: 	TMP3Parser parser(aReader, flags);
sl@0: 	TRAP_IGNORE(parser.ParseL());
sl@0: 	
sl@0: 	TInt confIndex = flags.GetBitField(KMP3ConfidenceMask);
sl@0: 	aMatch.iConfidence = KMP3FlagsToConfidence[confIndex];
sl@0: 	if (aMatch.iConfidence != KConfNotRecognised)
sl@0: 		{
sl@0: 		aMatch.iMime = KMimeMP3;
sl@0: 		}
sl@0: 	}
sl@0: 
sl@0: 
sl@0: //
sl@0: // Attempts to parse an mp3 file.
sl@0: // First of all it checks if there is an ID3 metadata header
sl@0: // present at the current reader position. Then it checks for up to
sl@0: // two consecutive mp3 audio frames.
sl@0: //
sl@0: void TMP3Parser::ParseL()
sl@0: 	{
sl@0: 	TInt length;
sl@0: 	TMP3State state = ESearchFrame1;
sl@0: 
sl@0: 	FOREVER
sl@0: 		{
sl@0: 		TID3Parser::ReadAndSkipID3L(iReader);
sl@0: 		
sl@0: 		TInt err = CheckForFrameHeaderL(length);
sl@0: 		if (err == KErrNotFound)
sl@0: 			{
sl@0: 			return;
sl@0: 			}
sl@0: 			
sl@0: 		switch (state)
sl@0: 			{
sl@0: 			case ESearchFrame1:
sl@0: 				iFlags.SetBit(KMP3Frame1Bit);
sl@0: 				state = ESearchFrame2;
sl@0: 				break;
sl@0: 					
sl@0: 			case ESearchFrame2:
sl@0: 				iFlags.SetBit(KMP3Frame2Bit);
sl@0: 				return;
sl@0: 			}
sl@0: 				
sl@0: 		// Skip over the audio frame.
sl@0: 		// This should be done after flags have been set.
sl@0: 		iReader.SeekL(length - KMP3FrameHeaderSize);
sl@0: 		}
sl@0: 	}
sl@0: 	
sl@0: 
sl@0: //
sl@0: // Checks for an MP3 frame header at the current reader position.
sl@0: // If one is not found KErrNotFound is returned and aFrameLength
sl@0: // remains unchanged. If one is found KErrNone is retured and
sl@0: // aFrameLength is set to the length of the frame.
sl@0: //
sl@0: TInt TMP3Parser::CheckForFrameHeaderL(TInt& aFrameLength)
sl@0: 	{
sl@0: 	TBuf8<KMP3FrameHeaderSize> data;
sl@0: 	TUint8 versionIndex;
sl@0: 	TUint8 layerIndex;
sl@0: 	TUint8 bitrateIndex;
sl@0: 	TUint8 sampleRateIndex;
sl@0: 	TUint8 padding;
sl@0: 	TUint8 sync;
sl@0: 	
sl@0: 	data.SetLength(KMP3FrameHeaderSize);
sl@0: 	iReader.ReadBytesL(data);
sl@0: 	
sl@0: 	do
sl@0: 		{
sl@0: 		sync = MP3_GET_SYNC1(data[0]);
sl@0: 		if (IS_BAD_MP3_FRAME_SYNC1(sync))
sl@0: 			{
sl@0: 			break;
sl@0: 			}
sl@0: 			
sl@0: 		sync = MP3_GET_SYNC2(data[1]);
sl@0: 		if (IS_BAD_MP3_FRAME_SYNC2(sync))
sl@0: 			{
sl@0: 			break;
sl@0: 			}
sl@0: 		
sl@0: 		versionIndex = MP3_GET_VERSION(data[1]);
sl@0: 		if (IS_BAD_MP3_VERSION(versionIndex))
sl@0: 			{
sl@0: 			break;
sl@0: 			}
sl@0: 			
sl@0: 		layerIndex = MP3_GET_LAYER(data[1]);
sl@0: 		if (IS_BAD_MP3_LAYER(layerIndex))
sl@0: 			{
sl@0: 			break;
sl@0: 			}
sl@0: 			
sl@0: 		bitrateIndex = MP3_GET_BITRATE(data[2]);
sl@0: 		if (IS_BAD_MP3_BITRATE(bitrateIndex))
sl@0: 			{
sl@0: 			break;
sl@0: 			}
sl@0: 			
sl@0: 		sampleRateIndex = MP3_GET_SAMPLE_RATE(data[2]);
sl@0: 		if (IS_BAD_MP3_SAMPLE_RATE(sampleRateIndex))
sl@0: 			{
sl@0: 			break;
sl@0: 			}
sl@0: 			
sl@0: 		padding = MP3_GET_PADDING(data[2]);
sl@0: 		
sl@0: 		// All the data is valid.
sl@0: 		// Compute the audio data length.
sl@0: 		TUint32 bitRate = KBad;
sl@0: 		TUint16 sampleRate = KBad;
sl@0: 		TUint16 samplesPerFrame = KBad;
sl@0: 		
sl@0: 		if (versionIndex == KMP3Version1)
sl@0: 			{
sl@0: 			bitRate = KBitrateVersion1[layerIndex][bitrateIndex];
sl@0: 			}
sl@0: 		else if (versionIndex == KMP3Version2)
sl@0: 			{
sl@0: 			bitRate = KBitrateVersion2[layerIndex][bitrateIndex];
sl@0: 			}
sl@0: 		else 
sl@0: 			{
sl@0: 			// Version 2.5 is not supported.
sl@0: 			break;
sl@0: 			}
sl@0: 
sl@0: 		sampleRate = KSampleRate[versionIndex][sampleRateIndex];
sl@0: 		samplesPerFrame = KSamplesPerFrame[layerIndex][versionIndex];
sl@0: 		
sl@0: 		// Check we have valid values.
sl@0: 		if ((bitRate == KBad) || (sampleRate == KBad) || (samplesPerFrame == KBad))
sl@0: 			{
sl@0: 			break;
sl@0: 			}
sl@0: 
sl@0: 		bitRate *= 1000; // Convert to kilobits.
sl@0: 		aFrameLength = (((samplesPerFrame / KBitsPerByte) * bitRate) / sampleRate) + padding;
sl@0: 		return KErrNone;
sl@0: 		}
sl@0: 	while (EFalse);
sl@0: 	
sl@0: 	// No valid frame header was found.
sl@0: 	aFrameLength = 0;
sl@0: 	iReader.SeekL(-KMP3FrameHeaderSize);
sl@0: 	return KErrNotFound;
sl@0: 	}
sl@0: 	
sl@0: 
sl@0: 
sl@0: