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116 lines
2.7 KiB
116 lines
2.7 KiB
//========= 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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