decode.c

Vovida 社区开源的 SIP 协议源码

/*
 * decode.c
 *
 * CCITT ADPCM decoder
 *
 * Usage : decode [-3|4|5] [-a|u|l] < infile > outfile
 */
#include <stdio.h>
#include <stdlib.h>
#include "g72x.h"


/*
 * Unpack input codes and pass them back as bytes.
 * Returns 1 if there is residual input, returns -1 if eof, else returns 0.
 */
int
unpack_input(
    unsigned char	*code,
    int	bits)
{
    static unsigned int	in_buffer = 0;
    static int	in_bits = 0;
    unsigned char	in_byte;

    if (in_bits < bits)
    {
        if (fread(&in_byte, sizeof (char), 1, stdin) != 1)
        {
            *code = 0;
            return ( -1);
        }
        in_buffer |= (in_byte << in_bits);
        in_bits += 8;
    }
    *code = in_buffer & ((1 << bits) - 1);
    in_buffer >>= bits;
    in_bits -= bits;
    return (in_bits > 0);
}


int main(
    int	argc,
    char	**argv)
{
    short	sample;
    unsigned char	code;
    struct g72x_state	state;
    int	out_coding;
    int	out_size;
    int	(*dec_routine)();
    int	dec_bits;

    g72x_init_state(&state);
    out_coding = AUDIO_ENCODING_ULAW;
    out_size = sizeof (char);
    dec_routine = g721_decoder;
    dec_bits = 4;

    /* Process encoding argument, if any */
    while ((argc > 1) && (argv[1][0] == '-'))
    {
        switch (argv[1][1])
        {
            case '3':
            dec_routine = g723_24_decoder;
            dec_bits = 3;
            break;
            case '4':
            dec_routine = g721_decoder;
            dec_bits = 4;
            break;
            case '5':
            dec_routine = g723_40_decoder;
            dec_bits = 5;
            break;
            case 'u':
            out_coding = AUDIO_ENCODING_ULAW;
            out_size = sizeof (char);
            break;
            case 'a':
            out_coding = AUDIO_ENCODING_ALAW;
            out_size = sizeof (char);
            break;
            case 'l':
            out_coding = AUDIO_ENCODING_LINEAR;
            out_size = sizeof (short);
            break;
            default:
            fprintf(stderr, "CCITT ADPCM Decoder -- usage:\n");
            fprintf(stderr, "\tdecode [-3|4|5] [-a|u|l] < infile > outfile\n");
            fprintf(stderr, "where:\n");
            fprintf(stderr, "\t-3\tProcess G.723 24kbps (3-bit) input data\n");
            fprintf(stderr, "\t-4\tProcess G.721 32kbps (4-bit) input data [default]\n");
            fprintf(stderr, "\t-5\tProcess G.723 40kbps (5-bit) input data\n");
            fprintf(stderr, "\t-a\tGenerate 8-bit A-law data\n");
            fprintf(stderr, "\t-u\tGenerate 8-bit u-law data [default]\n");
            fprintf(stderr, "\t-l\tGenerate 16-bit linear PCM data\n");
            exit(1);
        }
        argc--;
        argv++;
    }

    /* Read and unpack input codes and process them */
    while (unpack_input(&code, dec_bits) >= 0)
    {
        sample = (*dec_routine)(code, out_coding, &state);
        if (out_size == 2)
        {
            fwrite(&sample, out_size, 1, stdout);
        }
        else
        {
            code = (unsigned char)sample;
            fwrite(&code, out_size, 1, stdout);
        }
    }
    fclose(stdout);
    return 0;
}