cinelerra/filebaseulaw.C

   1 #include "assets.h"
   2 #include "byteorder.h"
   3 #include "file.h"
   4 #include "filebase.h"
   5 #include "sizes.h"
   6
   7 // ======================================= ulaw codecs
   8
   9 float FileBase::ulawtofloat(char ulaw)
  10 {
  11 //printf("%f\n", ulawtofloat_ptr[ulaw]);
  12         return ulawtofloat_ptr[(unsigned char)ulaw];
  13 }
  14
  15 char FileBase::floattoulaw(float value)
  16 {
  17         return floattoulaw_ptr[(int)(value * 32767)];
  18 }
  19
  20 // turn off the trap as per the MIL-STD
  21 #undef ZEROTRAP
  22 // define the add-in bias for 16 bit samples
  23 #define uBIAS 0x84
  24 #define uCLIP 32635
  25
  26 int FileBase::generate_ulaw_tables()
  27 {
  28         int i;
  29         float value;
  30
  31         if(!ulawtofloat_table)
  32         {
  33         static int exp_lut[8] = { 0, 132, 396, 924, 1980, 4092, 8316, 16764 };
  34         int sign, exponent, mantissa, sample;
  35                 unsigned char ulawbyte;
  36
  37                 ulawtofloat_table = new float[256];
  38                 ulawtofloat_ptr = ulawtofloat_table;
  39                 for(i = 0; i < 256; i++)
  40                 {
  41                         ulawbyte = (unsigned char)i;
  42                 ulawbyte = ~ ulawbyte;
  43                 sign = ( ulawbyte & 0x80 );
  44                 exponent = ( ulawbyte >> 4 ) & 0x07;
  45                 mantissa = ulawbyte & 0x0F;
  46                 sample = exp_lut[exponent] + ( mantissa << ( exponent + 3 ) );
  47                 if ( sign != 0 ) sample = -sample;
  48
  49                         ulawtofloat_ptr[(int)i] = (float)sample / 32768;
  50                 }
  51         }
  52
  53         if(!floattoulaw_table)
  54         {
  55         int sign, exponent, mantissa;
  56         unsigned char ulawbyte;
  57                 int sample;
  58         int exp_lut[256] = {0,0,1,1,2,2,2,2,3,3,3,3,3,3,3,3,
  59                                4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,
  60                                5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,
  61                                5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,
  62                                6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,
  63                                6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,
  64                                6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,
  65                                6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,
  66                                7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
  67                                7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
  68                                7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
  69                                7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
  70                                7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
  71                                7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
  72                                7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
  73                                7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7};
  74
  75                 floattoulaw_table = new unsigned char[65536];
  76                 floattoulaw_ptr = floattoulaw_table + 32768;
  77
  78                 for(i = -32768; i < 32768; i++)
  79                 {
  80                         sample = i;
  81 // Get the sample into sign-magnitude.
  82                 sign = (sample >> 8) & 0x80;            // set aside the sign
  83                 if ( sign != 0 ) sample = -sample;              // get magnitude
  84                 if ( sample > uCLIP ) sample = uCLIP;           // clip the magnitude
  85
  86 // Convert from 16 bit linear to ulaw.
  87                 sample = sample + uBIAS;
  88                     exponent = exp_lut[( sample >> 7 ) & 0xFF];
  89                     mantissa = ( sample >> ( exponent + 3 ) ) & 0x0F;
  90                     ulawbyte = ~ ( sign | ( exponent << 4 ) | mantissa );
  91 #ifdef ZEROTRAP
  92                     if ( ulawbyte == 0 ) ulawbyte = 0x02;       /* optional CCITT trap */
  93 #endif
  94
  95                     floattoulaw_ptr[i] = ulawbyte;
  96                 }
  97         }
  98         return 0;
  99 }
 100
 101 int FileBase::delete_ulaw_tables()
 102 {
 103         if(floattoulaw_table) delete [] floattoulaw_table;
 104         if(ulawtofloat_table) delete [] ulawtofloat_table;
 105         floattoulaw_table = 0;
 106         ulawtofloat_table = 0;
 107         return 0;
 108 }
 109 /*
 110 //      Local Variables:
 111 //      mode: C++
 112 //      c-file-style: "linux"
 113 //      End:
 114 */