www.pudn.com > G711-729.rar > decode.c

/* 
 * decode.c 
 * 
 * CCITT ADPCM decoder 
 * 
 * Usage : decode [-3|4|5] [-a|u|l] < infile > outfile 
 */ 
#include  
#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); 
} 
 
 
main( 
	int			argc, 
	char			**argv) 
{ 
	short			sample; 
	unsigned char		code; 
	int			n; 
	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); 
}