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Copyright (c) 1995 ISO/IEC JTC1 SC29 WG1, All Rights Reserved
Revision History:
Date Programmer Comment
========== ========================= ===============================
1995/09/06 created
#include "machine.h"
#define MAX_CHANNELS 2
#define MAX_GRANULES 2
This is the prototype for the function pointer you must
provide to write bits to the bitstream. It should write
'length' bits from 'value,' msb first. Bits in value are
assumed to be right-justified.
void putMyBits( u_int value, u_int length );
A BitstreamElement contains encoded data
to be written to the bitstream.
'length' bits of 'value' will be written to
the bitstream msb-first.
typedef struct
u_int value;
u_short length;
} BF_BitstreamElement;
A BitstreamPart contains a group
of 'nrEntries' of BitstreamElements.
Each BitstreamElement will be written
to the bitstream in the order it appears
in the 'element' array.
typedef struct
u_int nrEntries;
BF_BitstreamElement *element;
} BF_BitstreamPart;
This structure contains all the information needed by the
bitstream formatter to encode one frame of data. You must
fill this out and provide a pointer to it when you call
the formatter.
Maintainers: If you add or remove part of the side
information, you will have to update the routines that
make local copies of that information (in formatBitstream.c)
typedef struct BF_FrameData
int frameLength;
int nGranules;
int nChannels;
BF_BitstreamPart *header;
BF_BitstreamPart *frameSI;
BF_BitstreamPart *channelSI[MAX_CHANNELS];
BF_BitstreamPart *spectrumSI[MAX_GRANULES][MAX_CHANNELS];
BF_BitstreamPart *scaleFactors[MAX_GRANULES][MAX_CHANNELS];
BF_BitstreamPart *codedData[MAX_GRANULES][MAX_CHANNELS];
BF_BitstreamPart *userSpectrum[MAX_GRANULES][MAX_CHANNELS];
BF_BitstreamPart *userFrameData;
} BF_FrameData;
This structure contains information provided by
the bitstream formatter. You can use this to
check to see if your code agrees with the results
of the call to the formatter.
typedef struct BF_FrameResults
int SILength;
int mainDataLength;
int nextBackPtr;
} BF_FrameResults;
public functions in formatBitstream.c
/* Initialize the bitstream */
void InitFormatBitStream(void);
/* count the bits in a BitstreamPart */
int BF_PartLength( BF_BitstreamPart *part );
/* encode a frame of audio and write it to your bitstream */
void BF_BitstreamFrame( BF_FrameData *frameInfo, BF_FrameResults *results );
/* write any remaining frames to the bitstream, padding with zeros */
void BF_FlushBitstream( BF_FrameData *frameInfo, BF_FrameResults *results );
typedef struct BF_PartHolder
int max_elements;
BF_BitstreamPart *part;
} BF_PartHolder;
BF_PartHolder *BF_newPartHolder( int max_elements );
BF_PartHolder *BF_resizePartHolder( BF_PartHolder *oldPH, int max_elements );
BF_PartHolder *BF_addElement( BF_PartHolder *thePH, BF_BitstreamElement *theElement );
BF_PartHolder *BF_addEntry( BF_PartHolder *thePH, u_int value, u_int length );
BF_PartHolder *BF_NewHolderFromBitstreamPart( BF_BitstreamPart *thePart );
BF_PartHolder *BF_LoadHolderFromBitstreamPart( BF_PartHolder *theHolder, BF_BitstreamPart *thePart );
BF_PartHolder *BF_freePartHolder( BF_PartHolder *thePH );
#endif /* #ifndef _FORMAT_BITSTREAM_H */