common.c

mpeg文件格式类型的文档

/**********************************************************************
 * ISO MPEG Audio Subgroup Software Simulation Group (1996)
 * ISO 13818-3 MPEG-2 Audio Decoder - Lower Sampling Frequency Extension
 *
 * $Id: common.c,v 1.2 1996/03/28 03:13:37 rowlands Exp $
 *
 * $Log: common.c,v $
 * Revision 1.2  1996/03/28 03:13:37  rowlands
 * Merged layers 1-2 and layer 3 revisions
 *
 * Revision 1.1  1996/02/14 03:45:52  rowlands
 * Initial revision
 *
 * Received from FhG
 **********************************************************************/
/**********************************************************************
 *   date   programmers         comment                               *
 * 2/25/91  Doulas Wong,        start of version 1.0 records          *
 *          Davis Pan                                                 *
 * 5/10/91  W. Joseph Carter    Created this file for all common      *
 *                              functions and global variables.       *
 *                              Ported to Macintosh and Unix.         *
 *                              Added Jean-Georges Fritsch's          *
 *                              "bitstream.c" package.                *
 *                              Added routines to handle AIFF PCM     *
 *                              sound files.                          *
 *                              Added "mem_alloc()" and "mem_free()"  *
 *                              routines for memory allocation        *
 *                              portability.                          *
 *                              Added routines to convert between     *
 *                              Apple SANE extended floating point    *
 *                              format and IEEE double precision      *
 *                              floating point format.  For AIFF.     *
 * 02jul91 dpwe (Aware Inc)     Moved allocation table input here;    *
 *                              Tables read from subdir TABLES_PATH.  *
 *                              Added some debug printout fns (Write*)*
 * 7/10/91 Earle Jennings       replacement of the one float by FLOAT *
 *                              port to MsDos from MacIntosh version  *
 * 8/ 5/91 Jean-Georges Fritsch fixed bug in open_bit_stream_r()      *
 *10/ 1/91 S.I. Sudharsanan,    Ported to IBM AIX platform.           *
 *         Don H. Lee,                                                *
 *         Peter W. Farrett                                           *
 *10/3/91  Don H. Lee           implemented CRC-16 error protection   *
 *                              newly introduced functions are        *
 *                              I_CRC_calc, II_CRC_calc and           *
 *                              update_CRC. Additions and revisions   *
 *                              are marked with dhl for clarity       *
 *10/18/91 Jean-Georges Fritsch fixed bug in update_CRC(),            *
 *                              II_CRC_calc() and I_CRC_calc()        *
 * 2/11/92  W. Joseph Carter    Ported new code to Macintosh.  Most   *
 *                              important fixes involved changing     *
 *                              16-bit ints to long or unsigned in    *
 *                              bit alloc routines for quant of 65535 *
 *                              and passing proper function args.     *
 *                              Removed "Other Joint Stereo" option   *
 *                              and made bitrate be total channel     *
 *                              bitrate, irrespective of the mode.    *
 *                              Fixed many small bugs & reorganized.  *
 * 3/20/92 Jean-Georges Fritsch  fixed bug in start-of-frame search   *
 * 6/15/92 Juan Pineda          added refill_buffer(bs) "n"           *
 *                              initialization                        *
 * 7/08/92 Susanne Ritscher     MS-DOS, MSC6.0 port fixes             *
 * 7/27/92 Mike Li               (re-)Port to MS-DOS                  *
 * 8/19/92 Soren H. Nielsen     Fixed bug in I_CRC_calc and in        *
 *                              II_CRC_calc.  Added function: new_ext *
 *                              for better MS-DOS compatability       *
 * 3/10/93 Kevin Peterson       changed aiff_read_headers to handle   *
 *                              chunks in any order.  now returns     *
 *                              position of sound data in file.       *
 * 3/31/93 Jens Spille          changed IFF_* string compares to use  *
 *                              strcmp()                              *
 * 5/30/93 Masahiro Iwadare     removed the previous modification     *
 *                              for UNIX.                             *
 * 8/27/93 Seymour Shlien,      Fixes in Unix and MSDOS ports,        *
 *         Daniel Lauzon, and                                         *
 *         Bill Truerniet                                             *
 *--------------------------------------------------------------------*
 *  8/24/93 Masahiro Iwadare    Included IS modification in Layer III.*
 *                              Changed for 1 pass decoding.          *
 *  9/07/93 Toshiyuki Ishino    Integrated Layer III with Ver 3.9.    *
 *--------------------------------------------------------------------*
 * 11/20/93 Masahiro Iwadare    Integrated Layer III with Ver 4.0.    *
 *--------------------------------------------------------------------*
 *  7/14/94 Juergen Koller      rewind of bitbuffer added             *
 *--------------------------------------------------------------------*
 *  6/12/95 Soeren H. Nielsen   Bug fix in new_ext().                 *
 *  7/11/95 Soeren H. Nielsen   Changes for MPEG-2 LSF Layer I and II *
 **********************************************************************/

/***********************************************************************
*
*  Global Include Files
*
***********************************************************************/

#include        "common.h"

#ifdef  MACINTOSH

#include        <SANE.h>
#include        <pascal.h>

#endif

#include	<string.h> /* 1995-07-11 shn */
#include	<ctype.h>

/***********************************************************************
*
*  Global Variable Definitions
*
***********************************************************************/

char *mode_names[5] = { "stereo", "j-stereo", "dual-ch", "single-ch" , "multi-ch"};
char *layer_names[3] = { "I", "II", "III" };
char *version_names[2] = { "MPEG-2 LSF", "MPEG-1" };

/* 1: MPEG-1, 0: MPEG-2 LSF, 1995-07-11 shn */
double  s_freq[2][4] = {{22.05, 24, 16, 0}, {44.1, 48, 32, 0}};

/* 1: MPEG-1, 0: MPEG-2 LSF, 1995-07-11 shn */
int     bitrate[2][3][15] = {{
          {0,32,48,56,64,80,96,112,128,144,160,176,192,224,256},
          {0,8,16,24,32,40,48,56,64,80,96,112,128,144,160},
          {0,8,16,24,32,40,48,56,64,80,96,112,128,144,160}},
   
          {{0,32,64,96,128,160,192,224,256,288,320,352,384,416,448},
          {0,32,48,56,64,80,96,112,128,160,192,224,256,320,384},
          {0,32,40,48,56,64,80,96,112,128,160,192,224,256,320}
          }};

double FAR multiple[64] = {
2.00000000000000, 1.58740105196820, 1.25992104989487,
1.00000000000000, 0.79370052598410, 0.62996052494744, 0.50000000000000,
0.39685026299205, 0.31498026247372, 0.25000000000000, 0.19842513149602,
0.15749013123686, 0.12500000000000, 0.09921256574801, 0.07874506561843,
0.06250000000000, 0.04960628287401, 0.03937253280921, 0.03125000000000,
0.02480314143700, 0.01968626640461, 0.01562500000000, 0.01240157071850,
0.00984313320230, 0.00781250000000, 0.00620078535925, 0.00492156660115,
0.00390625000000, 0.00310039267963, 0.00246078330058, 0.00195312500000,
0.00155019633981, 0.00123039165029, 0.00097656250000, 0.00077509816991,
0.00061519582514, 0.00048828125000, 0.00038754908495, 0.00030759791257,
0.00024414062500, 0.00019377454248, 0.00015379895629, 0.00012207031250,
0.00009688727124, 0.00007689947814, 0.00006103515625, 0.00004844363562,
0.00003844973907, 0.00003051757813, 0.00002422181781, 0.00001922486954,
0.00001525878906, 0.00001211090890, 0.00000961243477, 0.00000762939453,
0.00000605545445, 0.00000480621738, 0.00000381469727, 0.00000302772723,
0.00000240310869, 0.00000190734863, 0.00000151386361, 0.00000120155435,
1E-20
};

/***********************************************************************
*
*  Global Function Definitions
*
***********************************************************************/

/* The system uses a variety of data files.  By opening them via this
   function, we can accommodate various locations. */

FILE *OpenTableFile(name)
char *name;
{
char fulname[80];
char *envdir;
FILE *f;

     fulname[0] = '\0';

#ifdef TABLES_PATH
       strcpy(fulname, TABLES_PATH);   /* default relative path for tables */
#endif /* TABLES_PATH */          /* (includes terminal path seperator */

#ifdef UNIX                       /* envir. variables for UNIX only */
       {
        char *getenv();

        envdir = getenv(MPEGTABENV);   /* check for environment */
        if(envdir != NULL)
            strcpy(fulname, envdir);
        strcat(fulname, PATH_SEPARATOR);  /* add a "/" on the end */
      }
#endif /* UNIX */

    strcat(fulname, name);
    if( (f=fopen(fulname,"r"))==NULL ) {
        fprintf(stderr,"OpenTable: could not find %s\n", fulname);

#ifdef UNIX
          if(envdir != NULL)
            fprintf(stderr,"Check %s directory '%s'\n",MPEGTABENV, envdir);
          else
            fprintf(stderr,"Check local directory './%s' or setenv %s\n",
                    TABLES_PATH, MPEGTABENV);
#else /* not unix : no environment variables */

#ifdef TABLES_PATH
            fprintf(stderr,"Check local directory './%s'\n",TABLES_PATH);
#endif /* TABLES_PATH */

#endif /* UNIX */

    }
    return f;
}

/***********************************************************************
/*
/* Read one of the data files ("alloc_*") specifying the bit allocation/
/* quatization parameters for each subband in layer II encoding
/*
/**********************************************************************/

int read_bit_alloc(table, alloc)        /* read in table, return # subbands */
int table;
al_table *alloc;
{
        unsigned int a, b, c, d, i, j;
        FILE *fp;
        char name[16], t[80];
        int sblim;

        strcpy(name, "alloc_0");

        switch (table) {
                case 0 : name[6] = '0';         break;
                case 1 : name[6] = '1';         break;
                case 2 : name[6] = '2';         break;
                case 3 : name[6] = '3';         break;
		case 4 : name[6] = '4';		break; /* LSF, added 1995-07-11 shn */
                default : name[6] = '0';
        }

        if (!(fp = OpenTableFile(name))) {
                printf("Please check bit allocation table %s\n", name);
                exit(1);
        }

        printf("using bit allocation table %s\n", name);

        fgets(t, 80, fp);
        sscanf(t, "%d\n", &sblim);
        while (!feof(fp)) {
                fgets(t, 80, fp);
                sscanf(t, "%d %d %d %d %d %d\n", &i, &j, &a, &b, &c, &d);
                        (*alloc)[i][j].steps = a;
                        (*alloc)[i][j].bits  = b;
                        (*alloc)[i][j].group = c;
                        (*alloc)[i][j].quant = d;
        }
        fclose(fp);
        return sblim;
}

/***********************************************************************
/*
/* Using the decoded info the appropriate possible quantization per
/* subband table is loaded
/*
/**********************************************************************/

int pick_table(fr_ps)   /* choose table, load if necess, return # sb's */
frame_params *fr_ps;
{
        int table, lay, ws, bsp, br_per_ch, sfrq,ver;
        int sblim = fr_ps->sblimit;     /* return current value if no load */
	         
	ver = fr_ps->header->version;
        lay = fr_ps->header->lay - 1;
        bsp = fr_ps->header->bitrate_index;
        br_per_ch = bitrate[ver][lay][bsp] / fr_ps->stereo;
        ws = fr_ps->header->sampling_frequency;
        sfrq = s_freq[ver][ws];

        /* decision rules refer to per-channel bitrates (kbits/sec/chan) */
	if (fr_ps->header->version == MPEG_AUDIO_ID) { /* MPEG-1 */
	    if ((sfrq == 48 && br_per_ch >= 56) ||
		(br_per_ch >= 56 && br_per_ch <= 80)) table = 0;
	    else if (sfrq != 48 && br_per_ch >= 96) table = 1;
	    else if (sfrq != 32 && br_per_ch <= 48) table = 2;
	    else table = 3;
	}
	else { /* MPEG-2 LSF */
	    table = 4;
	}

        if (fr_ps->tab_num != table) {
           if (fr_ps->tab_num >= 0)
              mem_free((void **)&(fr_ps->alloc));
           fr_ps->alloc = (al_table FAR *) mem_alloc(sizeof(al_table),
                                                         "alloc");
           sblim = read_bit_alloc(fr_ps->tab_num = table, fr_ps->alloc);
        }
        return sblim;
}

int js_bound(lay, m_ext)
int lay, m_ext;
{
static int jsb_table[3][4] =  { { 4, 8, 12, 16 }, { 4, 8, 12, 16},
                                { 0, 4, 8, 16} };  /* lay+m_e -> jsbound */

    if(lay<1 || lay >3 || m_ext<0 || m_ext>3) {
        fprintf(stderr, "js_bound bad layer/modext (%d/%d)\n", lay, m_ext);
        exit(1);
    }
    return(jsb_table[lay-1][m_ext]);
}

void hdr_to_frps(fr_ps) /* interpret data in hdr str to fields in fr_ps */
frame_params *fr_ps;
{
layer *hdr = fr_ps->header;     /* (or pass in as arg?) */

    fr_ps->actual_mode = hdr->mode;
    fr_ps->stereo = (hdr->mode == MPG_MD_MONO) ? 1 : 2;
    if (hdr->lay == 2)          fr_ps->sblimit = pick_table(fr_ps);
    else                        fr_ps->sblimit = SBLIMIT;
    if(hdr->mode == MPG_MD_JOINT_STEREO)
        fr_ps->jsbound = js_bound(hdr->lay, hdr->mode_ext);
    else
        fr_ps->jsbound = fr_ps->sblimit;
    /* alloc, tab_num set in pick_table */
}

void WriteHdr(fr_ps, s)
frame_params *fr_ps;
FILE *s;
{
layer *info = fr_ps->header;

   fprintf(s, "HDR: s=FFF, id=%X, l=%X, ep=%s, br=%X, sf=%X, pd=%X, ",
           info->version, info->lay, ((info->error_protection) ? "on" : "off"),
           info->bitrate_index, info->sampling_frequency, info->padding);
   fprintf(s, "pr=%X, m=%X, js=%X, c=%X, o=%X, e=%X\n",
           info->extension, info->mode, info->mode_ext,
           info->copyright, info->original, info->emphasis);
   fprintf(s, "alg.=%s, layer=%s, tot bitrate=%d, sfrq=%.1f\n",
           version_names[info->version], layer_names[info->lay-1],
	   bitrate[info->version][info->lay-1][info->bitrate_index],
           s_freq[info->version][info->sampling_frequency]);
   fprintf(s, "mode=%s, sblim=%d, jsbd=%d, ch=%d\n",
           mode_names[info->mode], fr_ps->sblimit, fr_ps->jsbound, fr_ps->stereo);
   fflush(s);
}

void WriteBitAlloc(bit_alloc, f_p, s)
unsigned int bit_alloc[2][SBLIMIT];
frame_params *f_p;
FILE *s;
{
int i,j;
int st = f_p->stereo;
int sbl = f_p->sblimit;
int jsb = f_p->jsbound;

    fprintf(s, "BITA ");
    for(i=0; i<sbl; ++i) {
        if(i == jsb) fprintf(s,"-");
        for(j=0; j<st; ++j)
            fprintf(s, "%1x", bit_alloc[j][i]);
    }
    fprintf(s, "\n");   fflush(s);
}