/* make_ulaw_au.c - Audio client that writes a .au file to stdout */

/*
 *  Copyright (C) 1995-2005 Jeffrey Chilton
 *
 *  Permission is granted to anyone to make or distribute copies of
 *  this program, in any medium, provided that the copyright notice
 *  and permission notice are preserved, and that the distributor
 *  grants the recipient permission for further redistribution as
 *  permitted by this notice.
 *  
 *  Author's E-mail address:  jwc@chilton.com
 *  
 */

#include <sys/types.h>
#include <sys/socket.h>
#include <errno.h>
#include <netinet/in.h>
#include <netdb.h>
#include <signal.h>
#include <stdio.h>

#define AUDIO_PORT 8480

#define BUFFER_SIZE 1024

#define HEADER_SIZE 28
#define SAMPLE_RATE 8000
#define SAMPLE_CHANNELS 1
#define	AU_FILE_MAGIC 0x2e736e64
#define	AU_FILE_MULAW_8 1

#define MAX_WAIT 300

unsigned char LinearToMuLaw(short sample);

main(argc, argv)
int argc;
char *argv[];
{
    register int i, j;
    int data_sock;
    struct sockaddr_in server;
    char buffer[BUFFER_SIZE];
    char header[HEADER_SIZE];
    long request;
    long l;
    int rc;

    /* Go away if can't write for MAX_WAIT seconds */

    signal(SIGALRM, SIG_DFL); 

    /* Create socket */

    data_sock = socket(AF_INET, SOCK_STREAM, 0);
    if (data_sock < 0)
    {
	perror("make_ulaw_au: opening socket");
	exit(1);
    }

    /* Connect socket to local audio service */

    server.sin_family = AF_INET;
    server.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
    server.sin_port = htons(AUDIO_PORT);

    rc = connect(data_sock, (struct sockaddr *)&server, sizeof(server));
    if (rc < 0)
    {
	perror("make_ulaw_au: connecting socket");
	exit(1);
    }

    request = (argc > 1 ? atol(argv[1]) : 1) * 32000;

    /* Write ``.au'' file header */

    l = htonl(AU_FILE_MAGIC);	memcpy(&header[0], &l, sizeof (u_long));
    l = htonl(HEADER_SIZE);	memcpy(&header[4], &l, sizeof (u_long));
    l = htonl(request / 4);	memcpy(&header[8], &l, sizeof (u_long));
    l = htonl(AU_FILE_MULAW_8);	memcpy(&header[12], &l, sizeof (u_long));
    l = htonl(SAMPLE_RATE);	memcpy(&header[16], &l, sizeof (u_long));
    l = htonl(SAMPLE_CHANNELS);	memcpy(&header[20], &l, sizeof (u_long));
    l = htonl(0L);		memcpy(&header[24], &l, sizeof (u_long));

    rc = write(1, header, HEADER_SIZE);
    if (rc < 0)
    {
	perror("make_ulaw_au: writing header");
	exit(1);
    }

    /* Compress data from server to stdout */

    while (request > 0)
    {
	i = request < BUFFER_SIZE ? request : BUFFER_SIZE;
	rc = read(data_sock, buffer, i);
	if (rc < 0)
	{
	    perror("make_ulaw_au: reading data socket");
	    exit(1);
	}

	if (rc == 0)
	{
	    exit(0);
	}

	request -= rc;

	/* Compress one channel to 8-bit mu-law */

	j = 0;
	for (i = 0; i < rc; i += 4)
	{
	    short in;
	    in = buffer[i + 2] + (buffer[i + 3] << 8);
	    buffer[j++] = LinearToMuLaw(in);
	}

	alarm(MAX_WAIT);
	rc = write(1, buffer, rc / 4);
	if (rc < 0)
	{
	    if (errno != EPIPE)
	    {
	        perror("make_ulaw_au: writing data");
	    }
	    exit(1);
	}

    }

    exit(0);

}

/* from http://hazelware.luggle.com/tutorials/mulawcompression.html */

const int cBias = 0x84;
const int cClip = 32635;

static char MuLawCompressTable[256] =
{
     0,0,1,1,2,2,2,2,3,3,3,3,3,3,3,3,
     4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,
     5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,
     5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,
     6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,
     6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,
     6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,
     6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,
     7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
     7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
     7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
     7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
     7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
     7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
     7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
     7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7
};

unsigned char LinearToMuLaw(short sample)
{
    int exponent;
    int mantissa;
    int compressedByte;
    int sign;

    sign = sample >> 8 & 0x80;
    if (sign)
    {
	sample = -sample;
    }
    if (sample > cClip)
    {
	sample = cClip;
    }
    sample = sample + cBias;
    exponent = MuLawCompressTable[(sample >> 7) & 0xFF];
    mantissa = sample >> (exponent + 3) & 0x0F;
    compressedByte = ~ (sign | (exponent << 4) | mantissa);

    return compressedByte;
}