testd_s.c

G.726 ADPCM算法在C语言上的实现代码

/* testd - Test adpcm decoder */   
   
#include <STDIO.H>    
#include <STDLIB.H>    
#include <STRING.H>    
#include <DOS.H>    
   
struct adpcm_state {   
    short      valprev_l;        /* Previous output value */   
    char       index_l;          /* Index into stepsize table */   
    short      valprev_r;        /* Previous output value */   
    char       index_r;          /* Index into stepsize table */   
};   
   
struct adpcm_state state;   
   
void adpcm_coder (short [], char [], int, struct adpcm_state *);   
void adpcm_decoder (char [], short [], int, struct adpcm_state *);   
   
#define NSAMPLES 20000    
   
char   abuf[NSAMPLES/2];   
short  sbuf[NSAMPLES];   
   
main() {   
    FILE    *f, *f2;   
    char    fname[64],fname2[64];   
    int     n;   
   
    printf("ADPCM 4:1 stereo decoder v1.0 by Patrick Aalto 1993\r\n");   
    if (_argc < 3 )   
    {   
        printf("Usage: %s infile outfile\r\n", _argv[0]);   
        exit(1);   
    }   
    strcpy(fname,_argv[1]);   
    strcpy(fname2,_argv[2]);   
   
    if ( NULL == (f2=fopen(fname2,"wb")) )   
    {   
        printf("Error opening '%s', terminating..\r\n", fname2);   
        exit(4);   
    }   
    if ( NULL == (f=fopen(fname,"rb")) )   
    {   
        printf("Error opening '%s', terminating..\r\n", fname);   
        exit(4);   
    }   
    printf("Decoding '%s' into '%s', please wait...\r\n", fname, fname2);   
    while( n = fread(&abuf,1,sizeof(abuf),f) )   
    {   
    adpcm_decoder(abuf, sbuf, n, &state);   
    fwrite(&sbuf,4,n,f2);   
    }   
    fclose(f);   
    fclose(f2);   
    exit(0);   
}