www.pudn.com > MP3Dec2Wav_04.rar > common.c

#include  
#include  
#include  
 
#include  
#include  
#include  
 
#include "mpg123.h" 
 
 
int tabsel_123[2][3][16] = { 
   { {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,} }, 
 
   { {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,} } 
}; 
 
long freqs[9] = { 44100, 48000, 32000, 
                  22050, 24000, 16000 , 
                  11025 , 12000 , 8000 }; 
 
int bitindex; 
unsigned char *wordpointer; 
 
 
#define HDRCMPMASK 0xfffffd00 
 
 
/* 
 * the code a header and write the information 
 * into the frame structure 
 */ 
int decode_header(struct frame *fr,unsigned long newhead) 
{ 
	long ltmp;  //wfz_added 
    if( newhead & (1<<20) ) { 
      fr->lsf = (newhead & (1<<19)) ? 0x0 : 0x1;   // lsf= 0(mpeg1), 1(mpeg2) 
      fr->mpeg25 = 0; 
    } 
    else { 
      fr->lsf = 1; 
      fr->mpeg25 = 1; 
    } 
 
 
    fr->lay = 4-((newhead>>17)&3); 
    if( ((newhead>>10)&0x3) == 0x3) { 
#ifndef BE_QUIET 
      fprintf(stderr,"Stream error\n"); 
      exit(1); 
#else 
      return (0); 
#endif 
    } 
    if(fr->mpeg25) { 
      fr->sampling_frequency = 6 + ((newhead>>10)&0x3);  // index of sampling_frequency in freqs[] 
    } 
    else 
      fr->sampling_frequency = ((newhead>>10)&0x3) + (fr->lsf*3); 
    fr->error_protection = ((newhead>>16)&0x1)^0x1; 
 
    if(fr->mpeg25) /* allow Bitrate change for 2.5 ... */ 
      fr->bitrate_index = ((newhead>>12)&0xf); 
 
    fr->bitrate_index = ((newhead>>12)&0xf); 
    fr->padding   = ((newhead>>9)&0x1); 
    fr->extension = ((newhead>>8)&0x1); 
    fr->mode      = ((newhead>>6)&0x3); 
    fr->mode_ext  = ((newhead>>4)&0x3); 
    fr->copyright = ((newhead>>3)&0x1); 
    fr->original  = ((newhead>>2)&0x1); 
    fr->emphasis  = newhead & 0x3; 
 
    fr->stereo    = (fr->mode == MPG_MD_MONO) ? 1 : 2; 
 
    if(!fr->bitrate_index) 
    { 
#ifndef BE_QUIET 
      fprintf(stderr,"Free format not supported.\n"); 
#endif 
      return (0); 
    } 
 
    switch(fr->lay) 
    { 
/*      case 1: 
#if 0 
		fr->do_layer = do_layer1; 
        fr->jsbound = (fr->mode == MPG_MD_JOINT_STEREO) ? 
                         (fr->mode_ext<<2)+4 : 32; 
        fr->framesize  = (long) tabsel_123[fr->lsf][0][fr->bitrate_index] * 12000; 
        fr->framesize /= freqs[fr->sampling_frequency]; 
        fr->framesize  = ((fr->framesize+fr->padding)<<2)-4; 
#else 
#ifndef BE_QUIET 
        fprintf(stderr,"layer=1 Not supported!\n"); 
#endif 
		 
#endif 
        break;*/ 
      case 2: 
//#if 1 
		fr->do_layer = do_layer2; 
// in layer2.c 
//        II_select_table(fr); 
//        fr->jsbound = (fr->mode == MPG_MD_JOINT_STEREO) ? 
//                         (fr->mode_ext<<2)+4 : fr->II_sblimit; 
        fr->framesize = (long) tabsel_123[fr->lsf][1][fr->bitrate_index] * 144000; 
        fr->framesize /= freqs[fr->sampling_frequency]; 
        fr->framesize += fr->padding - 4; 
//#endif 
        break; 
      case 3: 
        fr->do_layer = do_layer3; 
/* 
#if 0 
        if(fr->lsf) 
          ssize = (fr->stereo == 1) ? 9 : 17; 
        else 
          ssize = (fr->stereo == 1) ? 17 : 32; 
#endif 
 
#if 0 
        if(fr->error_protection) 
          ssize += 2; 
#endif*/ 
 
/*        ------- BEGIN OF MODIFICATIONS FOR mpglib.dll 
          Because LCC-Win32 made the Program crash at this 
          point, the following modification was necessary. 
          fr->framesize  = (long) tabsel_123[fr->lsf][2][fr->bitrate_index] * 144000; 
          fr->framesize /= freqs[fr->sampling_frequency]<<(fr->lsf); 
          fr->framesize = fr->framesize + fr->padding - 4; 
*/   
		//long ltmp; this declaration moved to the beginning of the founction 
		 
		ltmp  = (long) tabsel_123[fr->lsf][2][fr->bitrate_index] * 144000; 
		ltmp /= freqs[fr->sampling_frequency]<<(fr->lsf); 
		ltmp  = ltmp + fr->padding - 4; 
		fr->framesize=ltmp; 
/*        ------- END OF MODIFICATIONS FOR mpglib.dll 
*/ 
 
        break; 
      default: 
#ifndef BE_QUIET 
        fprintf(stderr,"Sorry, unknown layer type.\n"); 
#endif 
        return (0); 
    } 
 
    /*    print_header(fr); */ 
 
    return 1; 
} 
 
 
unsigned int getbits(int number_of_bits) 
{ 
  unsigned long rval; 
 
  if(!number_of_bits) 
    return 0; 
 
  { 
    rval = wordpointer[0]; 
    rval <<= 8; 
    rval |= wordpointer[1]; 
    rval <<= 8; 
    rval |= wordpointer[2]; 
    rval <<= bitindex; 
    rval &= 0xffffff; 
 
    bitindex += number_of_bits; 
 
    rval >>= (24-number_of_bits); 
 
    wordpointer += (bitindex>>3); 
    bitindex &= 7; 
  } 
  return rval; 
} 
 
unsigned int getbits_fast(int number_of_bits) 
{ 
  unsigned long rval; 
 
  { 
    rval = wordpointer[0]; 
    rval <<= 8; 
    rval |= wordpointer[1]; 
    rval <<= bitindex; 
    rval &= 0xffff; 
    bitindex += number_of_bits; 
 
    rval >>= (16-number_of_bits); 
 
    wordpointer += (bitindex>>3); 
    bitindex &= 7; 
  } 
  return rval; 
}