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333 lines
10 KiB
C++
333 lines
10 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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#if defined( WIN32) && !defined( _X360 )
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#include "winlite.h"
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#endif
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#include "tier0/platform.h"
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#include "MPAFile.h"
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// static variables
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const char *CMPAHeader::m_szLayers[] = { "Layer I", "Layer II", "Layer III" };
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const char *CMPAHeader::m_szMPEGVersions[] = {"MPEG 2.5", "", "MPEG 2", "MPEG 1" };
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const char *CMPAHeader::m_szChannelModes[] = { "Stereo", "Joint Stereo", "Dual Channel", "Single Channel" };
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const char *CMPAHeader::m_szEmphasis[] = { "None", "50/15ms", "", "CCIT J.17" };
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// tolerance range, look at expected offset +/- m_dwTolerance for subsequent frames
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const uint32 CMPAHeader::m_dwTolerance = 3; // 3 bytes
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// max. range where to look for frame sync
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const uint32 CMPAHeader::m_dwMaxRange = ( 256 * 1024 );
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// sampling rates in hertz: 1. index = MPEG Version ID, 2. index = sampling rate index
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const uint32 CMPAHeader::m_dwSamplingRates[4][3] =
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{
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{11025, 12000, 8000, }, // MPEG 2.5
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{0, 0, 0, }, // reserved
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{22050, 24000, 16000, }, // MPEG 2
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{44100, 48000, 32000 } // MPEG 1
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};
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// padding sizes in bytes for different layers: 1. index = layer
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const uint32 CMPAHeader::m_dwPaddingSizes[3] =
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{
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4, // Layer1
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1, // Layer2
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1 // Layer3
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};
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// bitrates: 1. index = LSF, 2. index = Layer, 3. index = bitrate index
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const uint32 CMPAHeader::m_dwBitrates[2][3][15] =
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{
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{ // MPEG 1
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{0,32,64,96,128,160,192,224,256,288,320,352,384,416,448,}, // Layer1
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{0,32,48,56, 64, 80, 96,112,128,160,192,224,256,320,384,}, // Layer2
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{0,32,40,48, 56, 64, 80, 96,112,128,160,192,224,256,320,} // Layer3
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},
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{ // MPEG 2, 2.5
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{0,32,48,56,64,80,96,112,128,144,160,176,192,224,256,}, // Layer1
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{0,8,16,24,32,40,48,56,64,80,96,112,128,144,160,}, // Layer2
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{0,8,16,24,32,40,48,56,64,80,96,112,128,144,160,} // Layer3
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}
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};
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// Samples per Frame: 1. index = LSF, 2. index = Layer
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const uint32 CMPAHeader::m_dwSamplesPerFrames[2][3] =
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{
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{ // MPEG 1
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384, // Layer1
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1152, // Layer2
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1152 // Layer3
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},
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{ // MPEG 2, 2.5
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384, // Layer1
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1152, // Layer2
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576 // Layer3
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}
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};
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// Samples per Frame / 8
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const uint32 CMPAHeader::m_dwCoefficients[2][3] =
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{
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{ // MPEG 1
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48, // Layer1
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144, // Layer2
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144 // Layer3
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},
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{ // MPEG 2, 2.5
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48, // Layer1
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144, // Layer2
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72 // Layer3
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}
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};
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// needed later for CRC check
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// sideinformation size: 1.index = lsf, 2. index = layer, 3. index = mono
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const uint32 CMPAHeader::m_dwSideinfoSizes[2][3][2] =
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{
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{ // MPEG 1 (not mono, mono
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{0,0}, // Layer1
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{0,0}, // Layer2
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{9,17} // Layer3
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},
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{ // MPEG 2, 2.5
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{0,0}, // Layer1
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{0,0}, // Layer2
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{17,32} // Layer3
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}
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};
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// constructor (throws exception if no frame found)
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CMPAHeader::CMPAHeader( CMPAFile* pMPAFile, uint32 dwExpectedOffset, bool bSubsequentFrame, bool bReverse ) :
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m_pMPAFile( pMPAFile ), m_dwSyncOffset( dwExpectedOffset ), m_dwRealFrameSize( 0 )
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{
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// first check at expected offset (extended for not subsequent frames)
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HeaderError error = IsSync( m_dwSyncOffset, !bSubsequentFrame );
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int nStep=1;
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int nSyncOffset;
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while( error != noError )
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{
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// either look in tolerance range
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if( bSubsequentFrame )
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{
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if( nStep > m_dwTolerance )
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{
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// out of tolerance range
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throw CMPAException( CMPAException::NoFrameInTolerance, pMPAFile->GetFilename() ? pMPAFile->GetFilename() : "??" );
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}
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// look around dwExpectedOffset with increasing steps (+1,-1,+2,-2,...)
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if( m_dwSyncOffset <= dwExpectedOffset )
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{
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nSyncOffset = dwExpectedOffset + nStep;
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}
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else
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{
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nSyncOffset = dwExpectedOffset - nStep++;
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}
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}
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// just go forward/backward to find sync
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else
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{
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nSyncOffset = ((int)m_dwSyncOffset) + (bReverse?-1:+1);
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}
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// is new offset within valid range?
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if( nSyncOffset < 0 || nSyncOffset > (int)((pMPAFile->m_dwEnd - pMPAFile->m_dwBegin) - MPA_HEADER_SIZE) || abs( (long)(nSyncOffset-dwExpectedOffset) ) > m_dwMaxRange )
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{
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// out of tolerance range
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throw CMPAException( CMPAException::NoFrame, pMPAFile->GetFilename() ? pMPAFile->GetFilename() : "??" );
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}
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m_dwSyncOffset = nSyncOffset;
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// found sync?
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error = IsSync( m_dwSyncOffset, !bSubsequentFrame );
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}
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}
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// destructor
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CMPAHeader::~CMPAHeader()
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{
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}
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// skips first 32kbit/s or lower bitrate frames to estimate bitrate (returns true if bitrate is variable)
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bool CMPAHeader::SkipEmptyFrames()
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{
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if( m_dwBitrate > 32 )
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return false;
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uint32 dwHeader;
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try
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{
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while( m_dwBitrate <= 32 )
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{
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m_dwSyncOffset += m_dwComputedFrameSize + MPA_HEADER_SIZE;
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dwHeader = m_pMPAFile->ExtractBytes( m_dwSyncOffset, MPA_HEADER_SIZE, false );
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if( IsSync( dwHeader, false ) != noError )
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return false;
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}
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}
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catch(CMPAException& /*Exc*/) // just catch the exception and return false
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{
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return false;
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}
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return true;
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}
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// in dwHeader stands 32bit header in big-endian format: frame sync at the end!
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// because shifts do only work for integral types!!!
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CMPAHeader::HeaderError CMPAHeader::DecodeHeader( uint32 dwHeader, bool bSimpleDecode )
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{
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// Check SYNC bits (last eleven bits set)
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if( (dwHeader >> 24 != 0xff) || ((((dwHeader >> 16))&0xe0) != 0xe0) )
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return noSync;
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// get MPEG version
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m_Version = (MPAVersion)((dwHeader >> 19) & 0x03); // mask only the rightmost 2 bits
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if( m_Version == MPEGReserved )
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return headerCorrupt;
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if( m_Version == MPEG1 )
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m_bLSF = false;
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else
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m_bLSF = true;
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// get layer (0 = layer1, 2 = layer2, ...)
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m_Layer = (MPALayer)(3 - ((dwHeader >> 17) & 0x03));
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if( m_Layer == LayerReserved )
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return headerCorrupt;
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// protection bit (inverted)
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m_bCRC = !((dwHeader >> 16) & 0x01);
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// bitrate
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BYTE bIndex = (BYTE)((dwHeader >> 12) & 0x0F);
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if( bIndex == 0x0F ) // all bits set is reserved
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return headerCorrupt;
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m_dwBitrate = m_dwBitrates[m_bLSF][m_Layer][bIndex] * 1000; // convert from kbit to bit
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if( m_dwBitrate == 0 ) // means free bitrate (is unsupported yet)
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return freeBitrate;
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// sampling rate
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bIndex = (BYTE)((dwHeader >> 10) & 0x03);
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if( bIndex == 0x03 ) // all bits set is reserved
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return headerCorrupt;
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m_dwSamplesPerSec = m_dwSamplingRates[m_Version][bIndex];
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// padding bit
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m_dwPaddingSize = m_dwPaddingSizes[m_Layer] * ((dwHeader >> 9) & 0x01);
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// calculate frame size
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m_dwComputedFrameSize = (m_dwCoefficients[m_bLSF][m_Layer] * m_dwBitrate / m_dwSamplesPerSec) + m_dwPaddingSize;
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m_dwSamplesPerFrame = m_dwSamplesPerFrames[m_bLSF][m_Layer];
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if( !bSimpleDecode )
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{
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// private bit
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m_bPrivate = (dwHeader >> 8) & 0x01;
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// channel mode
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m_ChannelMode = (ChannelMode)((dwHeader >> 6) & 0x03);
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// mode extension (currently not used)
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m_ModeExt = (BYTE)((dwHeader >> 4) & 0x03);
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// copyright bit
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m_bCopyright = (dwHeader >> 3) & 0x01;
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// original bit
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m_bCopyright = (dwHeader >> 2) & 0x01;
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// emphasis
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m_Emphasis = (Emphasis)(dwHeader & 0x03);
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if( m_Emphasis == EmphReserved )
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return headerCorrupt;
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}
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return noError;
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}
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CMPAHeader::HeaderError CMPAHeader::IsSync( uint32 dwOffset, bool bExtended )
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{
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HeaderError error = noSync;
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uint32 dwHeader = m_pMPAFile->ExtractBytes( dwOffset, MPA_HEADER_SIZE, false );
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// sync bytes found?
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if( (dwHeader & 0xFFE00000) == 0xFFE00000 )
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{
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error = DecodeHeader( dwHeader );
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if( error == noError )
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{
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// enough buffer to do extended check?
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if( bExtended )
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{
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// recursive call (offset for next frame header)
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dwOffset = m_dwSyncOffset+m_dwComputedFrameSize;
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try
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{
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CMPAHeader m_SubsequentFrame( m_pMPAFile, dwOffset, true );
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m_dwRealFrameSize = m_SubsequentFrame.m_dwSyncOffset - m_dwSyncOffset;
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}
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catch( CMPAException& Exc )
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{
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// could not find any subsequent frame, assume it is the last frame
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if( Exc.GetErrorID() == CMPAException::NoFrame )
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{
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if( dwOffset + m_pMPAFile->m_dwBegin > m_pMPAFile->m_dwEnd )
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m_dwRealFrameSize = m_pMPAFile->m_dwEnd - m_pMPAFile->m_dwBegin - m_dwSyncOffset;
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else
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m_dwRealFrameSize = m_dwComputedFrameSize;
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error = noError;
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}
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else
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error = noSync;
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}
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}
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}
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}
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return error;
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}
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// CRC-16 lookup table
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const uint16 CMPAHeader::wCRC16Table[256] =
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{
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0x0000, 0xC0C1, 0xC181, 0x0140, 0xC301, 0x03C0, 0x0280, 0xC241,
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0xC601, 0x06C0, 0x0780, 0xC741, 0x0500, 0xC5C1, 0xC481, 0x0440,
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0xCC01, 0x0CC0, 0x0D80, 0xCD41, 0x0F00, 0xCFC1, 0xCE81, 0x0E40,
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0x0A00, 0xCAC1, 0xCB81, 0x0B40, 0xC901, 0x09C0, 0x0880, 0xC841,
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0xD801, 0x18C0, 0x1980, 0xD941, 0x1B00, 0xDBC1, 0xDA81, 0x1A40,
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0x1E00, 0xDEC1, 0xDF81, 0x1F40, 0xDD01, 0x1DC0, 0x1C80, 0xDC41,
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0x1400, 0xD4C1, 0xD581, 0x1540, 0xD701, 0x17C0, 0x1680, 0xD641,
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0xD201, 0x12C0, 0x1380, 0xD341, 0x1100, 0xD1C1, 0xD081, 0x1040,
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0xF001, 0x30C0, 0x3180, 0xF141, 0x3300, 0xF3C1, 0xF281, 0x3240,
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0x3600, 0xF6C1, 0xF781, 0x3740, 0xF501, 0x35C0, 0x3480, 0xF441,
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0x3C00, 0xFCC1, 0xFD81, 0x3D40, 0xFF01, 0x3FC0, 0x3E80, 0xFE41,
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0xFA01, 0x3AC0, 0x3B80, 0xFB41, 0x3900, 0xF9C1, 0xF881, 0x3840,
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0x2800, 0xE8C1, 0xE981, 0x2940, 0xEB01, 0x2BC0, 0x2A80, 0xEA41,
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0xEE01, 0x2EC0, 0x2F80, 0xEF41, 0x2D00, 0xEDC1, 0xEC81, 0x2C40,
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0xE401, 0x24C0, 0x2580, 0xE541, 0x2700, 0xE7C1, 0xE681, 0x2640,
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0x2200, 0xE2C1, 0xE381, 0x2340, 0xE101, 0x21C0, 0x2080, 0xE041,
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0xA001, 0x60C0, 0x6180, 0xA141, 0x6300, 0xA3C1, 0xA281, 0x6240,
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0x6600, 0xA6C1, 0xA781, 0x6740, 0xA501, 0x65C0, 0x6480, 0xA441,
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0x6C00, 0xACC1, 0xAD81, 0x6D40, 0xAF01, 0x6FC0, 0x6E80, 0xAE41,
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0xAA01, 0x6AC0, 0x6B80, 0xAB41, 0x6900, 0xA9C1, 0xA881, 0x6840,
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0x7800, 0xB8C1, 0xB981, 0x7940, 0xBB01, 0x7BC0, 0x7A80, 0xBA41,
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0xBE01, 0x7EC0, 0x7F80, 0xBF41, 0x7D00, 0xBDC1, 0xBC81, 0x7C40,
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0xB401, 0x74C0, 0x7580, 0xB541, 0x7700, 0xB7C1, 0xB681, 0x7640,
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0x7200, 0xB2C1, 0xB381, 0x7340, 0xB101, 0x71C0, 0x7080, 0xB041,
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0x5000, 0x90C1, 0x9181, 0x5140, 0x9301, 0x53C0, 0x5280, 0x9241,
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0x9601, 0x56C0, 0x5780, 0x9741, 0x5500, 0x95C1, 0x9481, 0x5440,
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0x9C01, 0x5CC0, 0x5D80, 0x9D41, 0x5F00, 0x9FC1, 0x9E81, 0x5E40,
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0x5A00, 0x9AC1, 0x9B81, 0x5B40, 0x9901, 0x59C0, 0x5880, 0x9841,
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0x8801, 0x48C0, 0x4980, 0x8941, 0x4B00, 0x8BC1, 0x8A81, 0x4A40,
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0x4E00, 0x8EC1, 0x8F81, 0x4F40, 0x8D01, 0x4DC0, 0x4C80, 0x8C41,
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0x4400, 0x84C1, 0x8581, 0x4540, 0x8701, 0x47C0, 0x4680, 0x8641,
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0x8201, 0x42C0, 0x4380, 0x8341, 0x4100, 0x81C1, 0x8081, 0x4040
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};
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