mp3common.h

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/* ***** BEGIN LICENSE BLOCK *****
 * Version: RCSL 1.0/RPSL 1.0 
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 * Portions Copyright (c) 1995-2002 RealNetworks, Inc. All Rights Reserved. 
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 * the file under the RealNetworks Community Source License Version 1.0 
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 * in which case the RCSL will apply. You may also obtain the license terms 
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 * This file is part of the Helix DNA Technology. RealNetworks is the 
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 * ***** END LICENSE BLOCK ***** */ 

/**************************************************************************************
 * Fixed-point MP3 decoder
 * Jon Recker (jrecker@real.com), Ken Cooke (kenc@real.com)
 * June 2003
 *
 * mp3common.h - implementation-independent API's, datatypes, and definitions
 **************************************************************************************/

#ifndef _MP3COMMON_H
#define _MP3COMMON_H

#include "mp3dec.h"
#include "mp3statname.h"    /* do name-mangling for static linking */
#include "sdk_default_config.h"

#define MAX_SCFBD       4       /* max scalefactor bands per channel */
#define NGRANS_MPEG1    2
#define NGRANS_MPEG2    1

/* 11-bit syncword if MPEG 2.5 extensions are enabled */
#define SYNCWORDH       0xff
#define SYNCWORDL       0xe0

/* 12-bit syncword if MPEG 1,2 only are supported 
 * #define  SYNCWORDH       0xff
 * #define  SYNCWORDL       0xf0
 */

typedef struct _MP3DecInfo {
    /* pointers to platform-specific data structures */
    void *FrameHeaderPS;
    void *SideInfoPS;
    void *ScaleFactorInfoPS;
    void *HuffmanInfoPS;
    void *DequantInfoPS;
    void *IMDCTInfoPS;
    void *SubbandInfoPS;

    /* buffer which must be large enough to hold largest possible main_data section */
    unsigned char mainBuf[MAINBUF_SIZE];

    /* special info for "free" bitrate files */
    int freeBitrateFlag;
    int freeBitrateSlots;

    /* user-accessible info */
    int bitrate;
    int nChans;
    int samprate;
    int nGrans;             /* granules per frame */
    int nGranSamps;         /* samples per granule */
    int nSlots;
    int layer;
    MPEGVersion version;

    int mainDataBegin;
    int mainDataBytes;

    int part23Length[MAX_NGRAN][MAX_NCHAN];

} MP3DecInfo;

typedef struct _SFBandTable {
    short l[23];
    short s[14];
} SFBandTable;

/* decoder functions which must be implemented for each platform */
MP3DecInfo *AllocateBuffers(void);
void FreeBuffers(MP3DecInfo *mp3DecInfo);
void ClearBuffers(MP3DecInfo *mp3DecInfo);
int CheckPadBit(MP3DecInfo *mp3DecInfo);
int UnpackFrameHeader(MP3DecInfo *mp3DecInfo, unsigned char *buf);
int UnpackSideInfo(MP3DecInfo *mp3DecInfo, unsigned char *buf);
int DecodeHuffman(MP3DecInfo *mp3DecInfo, unsigned char *buf, int *bitOffset, int huffBlockBits, int gr, int ch);
int Dequantize(MP3DecInfo *mp3DecInfo, int gr);
int IMDCT(MP3DecInfo *mp3DecInfo, int gr, int ch);
int UnpackScaleFactors(MP3DecInfo *mp3DecInfo, unsigned char *buf, int *bitOffset, int bitsAvail, int gr, int ch);
int Subband(MP3DecInfo *mp3DecInfo, short *pcmBuf);

#ifdef USE_OUTSIDE_MP3_TABLE
/* mp3tabs.c - global ROM tables */
extern int (* samplerateTab)[3];
extern short (* bitrateTab)[3][15];
extern short (* samplesPerFrameTab)[3];
extern short * bitsPerSlotTab;
extern short (* sideBytesTab)[2];
extern short (* slotTab)[3][15];
extern SFBandTable (* sfBandTable)[3];
#else
/* mp3tabs.c - global ROM tables */
extern const int samplerateTab[3][3];
extern const short bitrateTab[3][3][15];
extern const short samplesPerFrameTab[3][3];
extern const short bitsPerSlotTab[3];
extern const short sideBytesTab[3][2];
extern const short slotTab[3][3][15];
extern const SFBandTable sfBandTable[3][3];
#endif  /* USE_OUTSIDE_MP3_TABLE */

#endif  /* _MP3COMMON_H */