语音压缩

开发平台：
Unix_Linux

costg711.c：源码内容
							/*
 *-------------------------------------------------------------------------
 *
 * CCITT G.711 u-law, A-law and linear PCM conversions.
 *       Version 94/12/30 - COST 232
 *
 * Usage :
 *
 * COSTG711 -au|ua|la|al|lu|ul|ll infile outfile
 *
 *     -au: A-law to u-law conversion
 *     -ua: u-law to A-law conversion
 *     -la: 16-bit linear PCM to A-law
 *     -al: A-law to 16-bit linear PCM
 *     -lu: 16-bit linear PCM to u-law
 *     -ul: u-law to 16-bit linear PCM
 *     -ll: 16-bit linear low/high byte swapping
 *
 *-------------------------------------------------------------------------
 *
 * The source code of Sun Microsystems, referenced below, has been modified by 
 *
 *    Boerge Lindberg
 *    Center for PersonKommunikation
 *    Aalborg University, Denmark
 *    e-mail : bli@cpk.auc.dk
 *
 * on behalf of the now concluded COST 232 Project on 
 *
 *    "Speech Recognition over the Telephone Network".
 *
 * Modifications concern the addition of a main program for file processing. 
 * Additonal changes:
 *
 * 94/02/10 : Low/high byte swapping added.
 * 94/12/30 : Bugs fixed:
 *
 *            Functions linear2alaw, linear2ulaw have been updated to correctly
 *            convert unquantized 16 bit values.
 *            Tables for direct u- to A-law and A- to u-law conversions have been
 *            corrected.
 *
 *-------------------------------------------------------------------------
 */
#include <stdio.h>
#include <string.h>
#include <stdarg.h>
#include <stdlib.h>
#include "g711.c"
/* 16 bit swapping */
short swap_linear (short pcm_val)
{ struct lohibyte { unsigned char lb, hb;}; 
  union { struct lohibyte b;
          short i;
        } exchange;
  unsigned char c;
  
  exchange.i      = pcm_val;
  c               = exchange.b.hb;
  exchange.b.hb   = exchange.b.lb; 
  exchange.b.lb   = c;
  return (exchange.i);
}
/*
 **************************************************************************
 **************************************************************************
*/
void PrintUsage (FILE *ef)
{ fprintf(ef, "CCITT G.711 u-law, A-law and linear PCM conversions.n");
  fprintf(ef, "          Version 94/12/30 - COST 232n");
  fprintf(ef, "nUsage:nn");
  fprintf(ef, "tcostg711 -au|ua|la|al|lu|ul|ll infile outfilenn");
  fprintf(ef, "tt-autA-law to u-law conversionn");
  fprintf(ef, "tt-uatu-law to A-law conversionn");
  fprintf(ef, "tt-lat16-bit linear PCM to A-lawn");
  fprintf(ef, "tt-altA-law to 16-bit linear PCMn"); 
  fprintf(ef, "tt-lut16-bit linear PCM to u-lawn");
  fprintf(ef, "tt-ultu-law to 16-bit linear PCMn"); 
  fprintf(ef, "tt-llt16-bit linear low/high byte swappingn"); 
}
/*
 **************************************************************************
 **************************************************************************
*/
#define BLOCK_SIZE 1024
union
{ unsigned char in_samples_char[BLOCK_SIZE];
  short in_samples_short[BLOCK_SIZE];
} inbuf;
union
{ unsigned char out_samples_char[BLOCK_SIZE];
  short out_samples_short[BLOCK_SIZE];
} outbuf;
int main(
        int                     argc,
        char                    **argv)
{
        short                   in_size, out_size, count;
        short                   (*char_short_routine)(unsigned char uval) = NULL;
        short                   (*short_short_routine)(short pcm_val) = NULL;
        unsigned char           (*char_char_routine)(unsigned char uval) = NULL;
        unsigned char           (*short_char_routine)(short     pcm_val) = NULL;
        FILE                    *infile, *outfile;
        if (argc != 4) {
          PrintUsage(stderr); 
          return 1; /* Exit, error code 1 */
        }
        
        out_size = sizeof (char);
        in_size = sizeof (char);
        switch (argv[1][1]) {
        case 'u':
                switch (argv[1][2]) {
                case 'a':
                        char_char_routine = ulaw2alaw;
                        break;
                case 'l':
                        out_size = sizeof (short);
                        char_short_routine = ulaw2linear;
                        break;
                }
                break;
        case 'a':
                switch (argv[1][2]) {
                case 'u':
                        char_char_routine = alaw2ulaw;
                        break;
                case 'l':
                        out_size = sizeof (short);
                        char_short_routine = alaw2linear;
                        break;
                }
                break;
        case 'l':
                in_size = sizeof (short);
                switch (argv[1][2]) {
                case 'u':
                        short_char_routine = linear2ulaw;
                        break;
                case 'a':
                        short_char_routine = linear2alaw;
                        break;
                case 'l':
                        out_size = sizeof (short);
                        short_short_routine = swap_linear;
                        break;
                }
                break;
        default:
                PrintUsage(stderr); return 1; /* Exit, error code 1 */
        }
        if ((infile = fopen(argv[2],"rb")) == NULL)
        { fprintf(stderr,"Cannot open input file %sn",argv[2]);
          return 1; /* Exit, error code 1 */
        }
        
        if ((outfile = fopen(argv[3],"wb")) == NULL)
        { fprintf(stderr,"Cannot open output file %sn",argv[3]);
          return 1; /* Exit, error code 1 */
        }
        
        /* Read input file and process */
        do
        {  short i;
           count = fread(&inbuf,in_size,BLOCK_SIZE,infile);
           switch (out_size) {
                
                case 1: switch(in_size) {
                        case 1: for (i=0; i < count; i++)
                                  outbuf.out_samples_char[i] = (*char_char_routine) 
                                    (inbuf.in_samples_char[i]);
                                break;
                        case 2: for (i=0; i < count; i++)
                                  outbuf.out_samples_char[i] = (*short_char_routine) 
                                    (inbuf.in_samples_short[i]);
                                break;
                        }
                        break;
                        
                case 2: switch(in_size) {
                        case 1: for (i=0; i < count; i++)
                                  outbuf.out_samples_short[i] = (*char_short_routine) 
                                    (inbuf.in_samples_char[i]);
                                break;
                        case 2: for (i=0; i < count; i++)
                                  outbuf.out_samples_short[i] = (*short_short_routine) 
                                    (inbuf.in_samples_short[i]);
                                break;
                        }
                        break;
                        
           } /* end switch */
           if (fwrite(&outbuf, out_size, count, outfile) != count)
             { fprintf(stderr,"Write Access Error, File=%s",argv[3]); return 1;}
        } while (count == BLOCK_SIZE);
        fclose(infile); 
        fclose(outfile);
        return 0; /* Exit, no errors */
}

						