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1 files changed, 116 insertions, 0 deletions

diff --git a/engine/audio/private/MPAHeader.h b/engine/audio/private/MPAHeader.h
new file mode 100644
index 0000000..3810124
--- /dev/null
+++ b/engine/audio/private/MPAHeader.h
@@ -0,0 +1,116 @@
+//========= Copyright Valve Corporation, All rights reserved. ============//
+//
+// Purpose: 
+//
+//=============================================================================
+
+#ifndef MPAHEADER_H
+#define MPAHEADER_H
+#ifdef _WIN32
+#pragma once
+#endif
+
+#pragma once
+
+#define MPA_HEADER_SIZE 4	// MPEG-Audio Header Size 32bit
+#define MAXTIMESREAD 5
+
+class CMPAFile;
+
+class CMPAHeader
+{
+public:
+	CMPAHeader( CMPAFile* pMPAFile, uint32 dwExpectedOffset = 0, bool bSubsequentFrame = false, bool bReverse = false );
+	~CMPAHeader();
+
+	bool SkipEmptyFrames();
+
+	// bitrate is in bit per second, to calculate in bytes => (/ 8)
+	uint32 GetBytesPerSecond() const { return m_dwBitrate / 8; };
+	// calc number of seconds from number of frames
+	uint32 GetLengthSecond(uint32 dwNumFrames) const { return dwNumFrames * m_dwSamplesPerFrame / m_dwSamplesPerSec; };
+	uint32 GetBytesPerSecond( uint32 dwNumFrames, uint32 dwNumBytes ) const { return dwNumBytes / GetLengthSecond( dwNumFrames ); };
+	bool IsMono() const { return (m_ChannelMode == SingleChannel)?true:false; };
+	// true if MPEG2/2.5 otherwise false
+	bool IsLSF() const { return m_bLSF;	};	
+
+private:
+	static const uint32 m_dwMaxRange;
+	static const uint32 m_dwTolerance;
+	static const uint32 m_dwSamplingRates[4][3];
+	static const uint32 m_dwPaddingSizes[3];
+	static const uint32 m_dwBitrates[2][3][15];
+	static const uint32 m_dwSamplesPerFrames[2][3];
+	static const uint32 m_dwCoefficients[2][3];
+
+	// necessary for CRC check (not yet implemented)
+	static const uint32 m_dwSideinfoSizes[2][3][2];
+	static const uint16 wCRC16Table[256];
+
+	bool m_bLSF;		// true means lower sampling frequencies (=MPEG2/MPEG2.5)
+	CMPAFile* m_pMPAFile;
+
+public:
+	static const char * m_szLayers[];
+	static const char * m_szMPEGVersions[];
+	static const char * m_szChannelModes[];
+	static const char * m_szEmphasis[];
+
+	enum MPAVersion
+	{
+		MPEG25 = 0,
+		MPEGReserved,
+		MPEG2,
+		MPEG1		
+	}m_Version;
+
+	enum MPALayer
+	{
+		Layer1 = 0,
+		Layer2,
+		Layer3,
+		LayerReserved
+	}m_Layer;
+
+	enum Emphasis
+	{
+		EmphNone = 0,
+		Emph5015,
+		EmphReserved,
+		EmphCCITJ17
+	}m_Emphasis;
+
+	enum ChannelMode
+	{
+		Stereo,
+		JointStereo,
+		DualChannel,
+		SingleChannel
+	}m_ChannelMode;
+	
+	uint32 m_dwSamplesPerSec;
+	uint32 m_dwSamplesPerFrame;
+	uint32 m_dwBitrate;	// in bit per second (1 kb = 1000 bit, not 1024)
+	uint32 m_dwSyncOffset;
+	uint32 m_dwComputedFrameSize, m_dwRealFrameSize;
+	uint32 m_dwPaddingSize;
+
+	// flags
+	bool m_bCopyright, m_bPrivate, m_bOriginal;
+	bool m_bCRC; 
+	uint8 m_ModeExt;
+	
+private:
+	enum HeaderError
+	{
+		noError,
+		noSync,
+		freeBitrate,
+		headerCorrupt
+	};
+
+	HeaderError DecodeHeader( uint32 dwHeader, bool bSimpleDecode = false );
+	inline HeaderError IsSync( uint32 dwOffset, bool bExtended );
+};
+
+#endif // MPAHEADER_H