encode.c

Vovida 社区开源的 SIP 协议源码

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


/*
 * Pack output codes into bytes and write them to stdout.
 * Returns 1 if there is residual output, else returns 0.
 */
int
pack_output(
    unsigned	code,
    int	bits)
{
    static unsigned int	out_buffer = 0;
    static int	out_bits = 0;
    unsigned char	out_byte;

    out_buffer |= (code << out_bits);
    out_bits += bits;
    if (out_bits >= 8)
    {
        out_byte = out_buffer & 0xff;
        out_bits -= 8;
        out_buffer >>= 8;
        fwrite(&out_byte, sizeof (char), 1, stdout);
    }
    return (out_bits > 0);
}


int main(
    int	argc,
    char	**argv)
{
    struct g72x_state	state;
    unsigned char	sample_char;
    short	sample_short;
    unsigned char	code;
    int	resid;
    int	in_coding;
    int	in_size;
    unsigned int *in_buf;
    int	(*enc_routine) (int, int, struct g72x_state*);
    int	enc_bits;

    g72x_init_state(&state);

    /* Set defaults to u-law input, G.721 output */
    in_coding = AUDIO_ENCODING_ULAW;
    in_size = sizeof (char);
    in_buf = (unsigned *) & sample_char;
    enc_routine = g721_encoder;
    enc_bits = 4;

    /* Process encoding argument, if any */
    while ((argc > 1) && (argv[1][0] == '-'))
    {
        switch (argv[1][1])
        {
            case '3':
            enc_routine = g723_24_encoder;
            enc_bits = 3;
            break;
            case '4':
            enc_routine = g721_encoder;
            enc_bits = 4;
            break;
            case '5':
            enc_routine = g723_40_encoder;
            enc_bits = 5;
            break;
            case 'u':
            in_coding = AUDIO_ENCODING_ULAW;
            in_size = sizeof (char);
            in_buf = (unsigned *) & sample_char;
            break;
            case 'a':
            in_coding = AUDIO_ENCODING_ALAW;
            in_size = sizeof (char);
            in_buf = (unsigned *) & sample_char;
            break;
            case 'l':
            in_coding = AUDIO_ENCODING_LINEAR;
            in_size = sizeof (short);
            in_buf = (unsigned *) & sample_short;
            break;
            default:
            fprintf(stderr, "CCITT ADPCM Encoder -- usage:\n");
            fprintf(stderr, "\tencode [-3|4|5] [-a|u|l] < infile > outfile\n");
            fprintf(stderr, "where:\n");
            fprintf(stderr, "\t-3\tGenerate G.723 24kbps (3-bit) data\n");
            fprintf(stderr, "\t-4\tGenerate G.721 32kbps (4-bit) data [default]\n");
            fprintf(stderr, "\t-5\tGenerate G.723 40kbps (5-bit) data\n");
            fprintf(stderr, "\t-a\tProcess 8-bit A-law input data\n");
            fprintf(stderr, "\t-u\tProcess 8-bit u-law input data [default]\n");
            fprintf(stderr, "\t-l\tProcess 16-bit linear PCM input data\n");
            exit(1);
        }
        argc--;
        argv++;
    }

    /* Read input file and process */
    while (fread(in_buf, in_size, 1, stdin) == 1)
    {
        code = (*enc_routine)(in_size == 2 ? sample_short : sample_char,
                              in_coding, &state);
        resid = pack_output(code, enc_bits);
    }

    /* Write zero codes until all residual codes are written out */
    while (resid)
    {
        resid = pack_output(0, enc_bits);
    }
    fclose(stdout);
    return 0;
}