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