formatbitstream.h

ISO mp3 sources (distribution 10) Layer 1/2/3, C Source, 512 k Sources of the Mpeg 1,2 layer 1,2

#ifndef _FORMAT_BITSTREAM_H
#define _FORMAT_BITSTREAM_H
/*********************************************************************
  Copyright (c) 1995 ISO/IEC JTC1 SC29 WG1, All Rights Reserved
  formatBitstream.h
**********************************************************************/

/*
  Revision History:

  Date        Programmer                Comment
  ==========  ========================= ===============================
  1995/09/06  [e-mail]           created

*/
#ifndef MAX_CHANNELS
#define MAX_CHANNELS 2
#endif

#ifndef MAX_GRANULES
#define MAX_GRANULES 2
#endif

/* Find the ANSI header for these! */
typedef unsigned int   uint32;
typedef unsigned short uint16;

/*
  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.
*/
typedef void (*BitsFcnPtr)( uint32 value, uint16 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
{
    uint32 value;
    uint16 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
{
    uint32              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
{
    BitsFcnPtr       putbits;  /* your low-level bitstream function */
    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;

/*
  The following is a shorthand bitstream syntax for
  the type of bitstream this package will create.
  The bitstream has headers and side information that
  are placed at appropriate sections to allow framing.
  The main data is placed where it fits in a manner
  similar to layer3, which means that main data for a
  frame may be written to the bitstream before the
  frame's header and side information is written.

BitstreamFrame()
{
    Header();
    FrameSI();

    for ( ch )
	ChannelSI();

    for ( gr )
	for ( ch )
	    SpectrumSI();

    MainData();
}

MainData()
{
    for ( gr )
	for ( ch )
	{
	    Scalefactors();
	    CodedData();
	    UserSpectrum();
	}
    UserFrameData();
}

*/

/*
  public functions in formatBitstream.c
*/

/* 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, uint32 value, uint16 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