common.h

mp3 source code decoder & encoder

//        that a bitstream frame contains either N or N+1 slots, 
//        depending on the value of the padding bit. The bitrate_index
//        is an index to a table. The bitrate_index indicates the 
//        total bitrate irrespective of the mode (stereo, joint_stereo,
//        dual_channel, single_channel).
//sampling_frequency:
//        Indicates the sampling frequency.
//padding_bit:
//        If this bit equals '1', the bitstream frame contains an 
//        additional slot to adjust the mean bitrate to the sampling 
//        frequency, otherwise this bit will be '0'. Padding is necessary
//        with sampling frequencies of 11.025 kHz, 22.05 kHz and 44.1 kHz.
//        Padding may also be required in free format.
//private_bit:
//        Bit for private use. This bit will not be used in the future 
//        by ISO/IEC.
//mode -- Indicates the mode according to Table 10. The joint stereo mode 
//        is intensity_stereo and/or ms_stereo.
//mode_extension:
//        These bits are used in joint_stereo mode. They indicate which 
//        type of joint stereo coding method is applied. The frequency 
//        ranges, over which the intensity_stereo and ms_stereo modes are
//        applied, are implicit in the algorithm.
//copyright:
//        If this bit equals '0', there is no copyright on the Layer3 bitstream,
//        '1' means copyright protected.
//original/copy:
//        This bit equals '0' if the bitstream is a copy and '1' if it is an 
//        original.
//emphasis:
//        Indicates the type of de-emphasis that shall be used.
//================================================================

typedef struct {
	int IDex;                         //Add by SinceLuo 2002/3/18
    int version;
    int lay;
    int error_protection;
    int bitrate_index;
    int sampling_frequency;
    int padding;
    int extension;
    int mode;                        //Indicate Channal Mode
    int mode_ext;
    int copyright;
    int original;
    int emphasis;
} layer, *the_layer;

/* Parent Structure Interpreting some Frame Parameters in Header */

typedef struct {
    layer       *header;        /* raw header information */
    int         actual_mode;    /* when writing IS, may forget if 0 chs */
    al_table    *alloc;         /* bit allocation table read in */
    int         tab_num;        /* number of table as loaded */
    int         VoiceChannelNum; /* 1 for mono, 2 for stereo */
    int         jsbound;        /* first band of joint stereo coding */
    int         sblimit;        /* total number of sub bands */
} frame_params;

/* Double and SANE Floating Point Type Definitions */

typedef struct  IEEE_DBL_struct {
    unsigned long   hi;
    unsigned long   lo;
} IEEE_DBL;

typedef struct  SANE_EXT_struct {
    unsigned long   l1;
    unsigned long   l2;
    unsigned short  s1;
} SANE_EXT;


/* "bit_stream.h" Type Definitions */

typedef struct  bit_stream_struc {
    FILE        *pt;            /* pointer to bit stream device */
    unsigned char *buf;         /* bit stream buffer */
    int         buf_size;       /* size of buffer (in number of bytes) */
    long        totbit;         /* bit counter of bit stream */
    int         buf_byte_idx;   /* pointer to top byte in buffer */
    int         buf_bit_idx;    /* pointer to top bit of top byte in buffer */
    int         mode;           /* bit stream open in read or write mode */
    int         eob;            /* end of buffer index */
    int         eobs;           /* end of bit stream flag */
    char        format;
    
    /* format of file in rd mode (BINARY/ASCII) */
} Bit_stream_struc;

/* Layer III side information. */
typedef struct {
	unsigned part2_3_length;
	unsigned big_values;
	unsigned global_gain;
	unsigned scalefac_compress;
	unsigned window_switching_flag;
	unsigned block_type;
	unsigned mixed_block_flag;
	unsigned table_select[3];
	unsigned subblock_gain[3];
	unsigned region0_count;
	unsigned region1_count;
	unsigned preflag;
	unsigned scalefac_scale;
	unsigned count1table_select;
} my_gr_info ;

typedef struct 
{
	unsigned part2_3_length;
	unsigned big_values;
	unsigned global_gain;
	unsigned scalefac_compress;
	unsigned window_switching_flag;
	unsigned block_type;
	unsigned mixed_block_flag;
	unsigned table_select[3];
	unsigned subblock_gain[3];
	unsigned region0_count;
	unsigned region1_count;
	unsigned preflag;
	unsigned scalefac_scale;
	unsigned count1table_select;
}gr_info_s;
		
typedef struct {
	unsigned main_data_begin;
	unsigned private_bits;
	struct {
	    unsigned scfsi[4];
		gr_info_s gr[2];
		} ch[2];
	} III_side_info_t;

/* Layer III scale factors. */

typedef struct {
	int l[23];            /* [cb] */
	int s[3][13];         /* [window][cb] */
	} III_scalefac_t[2];  /* [ch] */

/***********************************************************************
*
*  Global Variable External Declarations
*
***********************************************************************/

extern char     *layer_names[3];
extern char	*version_names[2];
extern double   s_freq[3][4];
extern int      bitrate[2][3][15];
extern double multiple[64];

/***********************************************************************
*
*  Global Function Prototype Declarations
*
***********************************************************************/

/* The following functions are in the file "common.c" */

extern FILE           *OpenTableFile(char*);
extern int            read_bit_alloc(int, al_table*);
extern int            pick_table(frame_params*);
extern int            js_bound(int, int);
extern void           hdr_to_frps(frame_params*);
extern void           WriteMP3Header(frame_params*, FILE*);
extern void           WriteBitAlloc(unsigned int[2][SBLIMIT], frame_params*,
                        FILE*);
extern void           WriteScale(unsigned int[2][SBLIMIT],
                        unsigned int[2][SBLIMIT], unsigned int[2][3][SBLIMIT],
                        frame_params*, FILE*);
extern void           WriteSamples(int, unsigned int [SBLIMIT],
                        unsigned int[SBLIMIT], frame_params*, FILE*);
extern int            NumericQ(char*);
extern int            BitrateIndex(int, int, int);
extern int            SmpFrqIndex(long, int*);
extern int            memcheck(char*, int, int);
extern void           *mem_alloc(unsigned long);
extern void           mem_free(void**);
extern void           double_to_extended(double*, char[10]);
extern void           extended_to_double(char[10], double*);
extern void            refill_buffer(Bit_stream_struc*);
extern void           empty_buffer(Bit_stream_struc*, int);
extern void           open_bit_stream_write(Bit_stream_struc*, char*, int);
extern BOOL           open_bit_stream_read(Bit_stream_struc*, char*, int);
extern void           close_bit_stream_read(Bit_stream_struc*);
extern void           close_bit_stream_write(Bit_stream_struc*);
extern void           alloc_buffer(Bit_stream_struc*, int);
extern void           desalloc_buffer(Bit_stream_struc*);
extern void           back_track_buffer(Bit_stream_struc*, int);
extern unsigned int   get1bit(Bit_stream_struc*);
extern void           put1bit(Bit_stream_struc*, int);
extern unsigned long  look_ahead(Bit_stream_struc*, int);
extern unsigned long  getbits(Bit_stream_struc*, int);
extern void           putbits(Bit_stream_struc*, unsigned int, int);
extern void           byte_ali_putbits(Bit_stream_struc*, unsigned int, int);
extern unsigned long  byte_ali_getbits(Bit_stream_struc*, int);
extern unsigned long  sstell(Bit_stream_struc*);
extern int            end_bs(Bit_stream_struc*);
extern int            seek_sync(Bit_stream_struc*, long, int);
extern void           I_CRC_calc(frame_params*, unsigned int[2][SBLIMIT],
                        unsigned int*);
extern void           II_CRC_calc(frame_params*, unsigned int[2][SBLIMIT],
                        unsigned int[2][SBLIMIT], unsigned int*);
extern void           update_CRC(unsigned int, unsigned int, unsigned int*);
extern void           read_absthr(FLOAT*, int);
extern unsigned int   hget1bit(); /* MI */
extern unsigned long  hgetbits(int);
extern unsigned long  hsstell();
extern void           hputbuf(unsigned int,int);
extern void           rewindNbytes( int );
enum byte_order DetermineByteOrder();
void SwapBytesInWords( short *loc, int words );
void rewindNbits(int N);


#endif