File: cddaslave.c

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/*
 * This file is part of WorkMan, the civilized CD player program
 * (c) 1991-1997 by Steven Grimm (original author)
 * (c) by Dirk F�rsterling (current 'author' = maintainer)
 * The maintainer can be contacted by his e-mail address:
 * milliByte@DeathsDoor.com
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * Digital audio manipulator for WorkMan.
 *
 * The CDDA architecture looks like this:
 *
 *                     WorkMan  (or another UI!)
 *                       ^^^
 *                       |||    (separate processes connected by pipe)
 *                       vvv
 *     +------------- cddaslave -------------+
 *     |                  |                  |
 * command module    CDDA reader       audio output
 * (portable)        (per platform)    (per platform)
 *
 * This source file has the command module and some of the scaffolding
 * to hold cddaslave together, plus some non-system-dependent audio
 * processing code.  Look in plat_*_cdda.c for system-specific stuff.
 *
 */

#include "config.h"

#ifdef BUILD_CDDA
 
static char cddaslave_id[] = "$Id: cddaslave.c,v 1.3.4.1 1999/01/15 08:47:35 dirk Exp $";

#include <stdio.h>
#include <sys/types.h>
#define __USE_GNU
#include <sys/time.h>
#include "wmcdda.h"
#include "plat_.h"


int	playing = 0;		/* Should the CD be playing now? */

/*
 * Loudness setting, plus the floating volume multiplier and decaying-average
 * volume level.
 */
int		loudness = 0;
unsigned int	volume = 32768;
unsigned int	level;

/*
 * Playback speed (0 = slow)
 */
int		speed = 128;

/*
 * This is non-null if we're saving audio to a file.
 */
FILE		*output = NULL;

/*
 * Audio file header format.
 */
typedef unsigned long	u_32;
struct auheader {
	u_32	magic;
	u_32	hdr_size;
	u_32	data_size;
	u_32	encoding;
	u_32	sample_rate;
	u_32	channels;
};

/* had to change #ifdef to #if   -> see wmcdda.h */
#if WM_BIG_ENDIAN
# ifndef htonl
#  define htonl(x) (x)
# endif
#else
extern unsigned long htonl(x);
#endif

void *malloc();
long cdda_transform();

/*
 * Send status information upstream.
 */
void
send_status(blk)
	struct cdda_block	*blk;
{
	write(1, blk, sizeof(*blk));
}

/*
 * Accept a command from our master.
 *
 * The protocol is byte-oriented:
 *   PmsfMSFxyz		Play from msf to MSF (MSF can be 0,0,0 to play to end)
 *			xyz is the msf of the start of this chunk, i.e., the
 *			ending boundary for reverse play.
 *   S                  Stop.
 *   E                  Eject.  This means we just close the CD device and
 *                      open it again later.
 *   Q			Quit.
 *   Vn 		Set volume level (0-255).
 *   Bn			Set balance level (0-255).
 *   EnL		Set an equalizer level (n = 0 for bass, 255 for treble)
 *   G			Get current status.
 *   sn                 Set speed multiplier to n.
 *   dn			Set direction to forward (n = 0) or reverse.
 *   Fllllx...          Start saving to a file (length = l, followed by name)
 *   F0000              Stop saving.
 *   Ln			Set loudness level (0-255).
 */
int
command(cd_fd, blk)
	int			cd_fd;
	struct cdda_block	*blk;
{
	unsigned char		inbuf[10];
	char			*filename;
	int			namelen;
	struct auheader		hdr;

	if (read(0, inbuf, 1) <= 0)	/* Parent died. */
	{
		wmcdda_close();
		wmaudio_close();
		exit(0);
	}

	switch (inbuf[0]) {
	case 'E':
		playing = 0;
		wmaudio_stop();
		wmcdda_close(cd_fd);
		cd_fd = -1;
	        blk->status = WMCDDA_ACK;
	        send_status(blk);
		break;
	case 'P':
		read(0, inbuf, 9);
		playing = 1;

		wmaudio_stop();

		wmcdda_setup(inbuf[0] * 60 * 75 + inbuf[1] * 75 + inbuf[2],
			inbuf[3] * 60 * 75 + inbuf[4] * 75 + inbuf[5],
			inbuf[6] * 60 * 75 + inbuf[7] * 75 + inbuf[8]);

		wmaudio_ready();

		level = 2500;
		volume = 1 << 15;

		blk->status = WMCDDA_ACK;
		send_status(blk);
		break;

	case 'S':
		playing = 0;
		wmaudio_stop();
		blk->status = WMCDDA_ACK;
		send_status(blk);
		blk->status = WMCDDA_STOPPED;
		send_status(blk);
		break;

	case 'B':
		read(0, inbuf, 1);
		wmaudio_balance(inbuf[0]);
		blk->status = WMCDDA_ACK;
		send_status(blk);
		break;

	case 'V':
		read(0, inbuf, 1);
		wmaudio_volume(inbuf[0]);
		blk->status = WMCDDA_ACK;
		send_status(blk);
		break;

	case 'G':
		blk->status = WMCDDA_ACK;
		send_status(blk);

		if (playing)
			blk->status = WMCDDA_PLAYED;
		else
			blk->status = WMCDDA_STOPPED;
		wmaudio_state(blk);
		send_status(blk);
		break;

	case 'Q':
		blk->status = WMCDDA_ACK;
		send_status(blk);
		wmcdda_close();
		wmaudio_close();
		exit(0);

	case 's':
		read(0, inbuf, 1);
		speed = inbuf[0];
		wmcdda_speed(speed);
		blk->status = WMCDDA_ACK;
		send_status(blk);
		break;

	case 'd':
		read(0, inbuf, 1);
		wmcdda_direction(inbuf[0]);
		blk->status = WMCDDA_ACK;
		send_status(blk);
		break;

	case 'L':
		read(0, inbuf, 1);
		loudness = inbuf[0];
		blk->status = WMCDDA_ACK;
		send_status(blk);
		break;

	case 'F':
		read(0, &namelen, sizeof(namelen));
		if (output != NULL)
		{
			fclose(output);
			output = NULL;
		}
		if (namelen)
		{
			filename = malloc(namelen + 1);
			if (filename == NULL)
			{
				perror("cddaslave");
				wmcdda_close();
				wmaudio_close();
				exit(1);
			}

			read(0, filename, namelen);
			filename[namelen] = '\0';
			output = fopen(filename, "w");
			if (output == NULL)
				perror(filename);
			else
			{
				/* Write an .au file header. */
				hdr.magic = htonl(0x2e736e64);
				hdr.hdr_size = htonl(sizeof(hdr) + 28);
				hdr.data_size = htonl(~0);
				hdr.encoding = htonl(3);	/* linear-16 */
				hdr.sample_rate = htonl(44100);
				hdr.channels = htonl(2);

				fwrite(&hdr, sizeof(hdr), 1, output);
				fwrite("Recorded from CD by WorkMan", 28, 1,
					output);
			}

			free(filename);
		}

		blk->status = WMCDDA_ACK;
		send_status(blk);
	}
	return(cd_fd);
}

/*
 * Transform some CDDA data.
 */
long
wmcdda_transform(unsigned char *rawbuf, long buflen, struct cdda_block *block)
{
	long		i;
	long		*buf32 = (long *)rawbuf;
	register short	*buf16 = (short *)rawbuf;
	register int	aval;

	/*
	 * Loudness transformation.  Basically this is a self-adjusting
	 * volume control; our goal is to keep the average output level
	 * around a certain value (2500 seems to be pleasing.)  We do this
	 * by maintaining a decaying average of the recent output levels
	 * (where "recent" is some fraction of a second.)  All output levels
	 * are multiplied by the inverse of the decaying average; this has
	 * the volume-leveling effect we desire, and isn't too CPU-intensive.
	 *
	 * This is done by modifying the digital data, rather than adjusting
	 * the system volume control, because (at least on some systems)
	 * tweaking the system volume can generate little pops and clicks.
	 *
	 * There's probably a more elegant way to achieve this effect, but
	 * what the heck, I never took a DSP class and am making this up as
	 * I go along, with a little help from some friends.
	 *
	 * This is all done with fixed-point math, oriented around powers
	 * of two, which with luck will keep the CPU usage to a minimum.
	 * More could probably be done, for example using lookup tables to
	 * replace multiplies and divides; whether the memory hit (128K
	 * for each table) is worthwhile is unclear.
	 */
	if (loudness)
	{
		/* We aren't really going backwards, but i > 0 is fast */
		for (i = buflen / 2; i > 0; i--)
		{
			/*
			 * Adjust this sample to the current level.
			 */
			aval = (*buf16 = (((long)*buf16) * volume) >> 15);
			buf16++;

			/*
			 * Don't adjust the decaying average for each sample;
			 * that just spends CPU time for very little benefit.
			 */
			if (i & 127)
				continue;

			/*
			 * We want to use absolute values to compute the
			 * decaying average; otherwise it'd sit around 0.
			 */
			if (aval < 0)
				aval = -aval;

			/*
			 * Adjust more quickly when we start hitting peaks,
			 * or we'll get clipping when there's a sudden loud
			 * section after lots of quiet.
			 */
			if (aval & ~8191)
				aval <<= 3;

			/*
			 * Adjust the decaying average.
			 */
			level = ((level << 11) - level + aval) >> 11;

			/*
			 * Let *really* quiet sounds play softly, or we'll
			 * amplify background hiss to full volume and blast
			 * the user's speakers when real sound starts up.
			 */
			if (! (level & ~511))
				level = 512;

			/*
			 * And adjust the volume setting using the inverse
			 * of the decaying average.
			 */
			volume = (2500 << 15) / level;
		}
	}

	if (speed == 128)
		return (buflen);

	/*
	 * Half-speed play.  Stretch things out.
	 */
	if (speed == 0)
	{
		buflen /= 2;	/* Since we're moving 32 bits at a time */

		for (i = buflen - 1; i > 0; i--)
		{
			buf32[i] = buf32[i / 2];
		}

		buflen *= 4;	/* 2 for doubling the buffer, 2 from above */
	}

	/*
	 * Slow play; can't optimize it as well as half-speed.
	 */
	if (speed && speed < 128)
	{
		int	multiplier = ((speed + 128) * 128) / 256;
		int	newlen;
		int	tally = 0, pos;

		buflen /= 4;	/* Get the number of 32-bit values */

		/*
		 * Buffer length doubles when speed is 0, stays the same
		 * when speed is 128.
		 */
		newlen = (buflen * 128) / multiplier;

		pos = buflen - 1;
		for (i = newlen - 1; i > 0; i--)
		{
			buf32[i] = buf32[pos];
			tally += multiplier;
			if (tally & 128)
			{
				pos--;
				tally ^= 128;
			}
		}

		buflen = newlen * 4;
	}

	return (buflen);
}


main(argc, argv)
	char	**argv;
{
	int			cd_fd = 3;
	fd_set			readfd, dummyfd;
	struct timeval		timeout;
	char			*cddabuf;
	long			cddabuflen;
	struct cdda_block	blockinfo;
	long			result;
	int			nfds;
	char			*devname;

	/*
	 * Device name should be the command-line argument.
	 */
	if (argc < 2)
		devname = "";
	else
		devname = argv[1];

	/*
	 * If we're running setuid root, bump up our priority then lose
	 * superuser access.
	 */
	nice(-14);
	setuid(getuid());

	FD_ZERO(&dummyfd);
	FD_ZERO(&readfd);

	timerclear(&timeout);

	cd_fd = wmcdda_init(&cddabuf, &cddabuflen, cd_fd, devname);
	if (cd_fd < 0)
		exit(1);
	wmaudio_init();

	blockinfo.status = WMCDDA_ACK;
	send_status(&blockinfo);
	blockinfo.status = WMCDDA_STOPPED;

	/*
	 * Accept commands as they come in, and play some sound if we're
	 * supposed to be doing that.
	 */
	while (1)
	{
		FD_SET(0, &readfd);

		/*
		 * If we're playing, we don't want select to block.  Otherwise,
		 * wait a little while for the next command.
		 */
		if (playing)
			timeout.tv_usec = 0;
		else
			timeout.tv_usec = 500000;

		nfds = select(1, &readfd, &dummyfd, &dummyfd, &timeout);

		if (nfds < 0)	/* Broken pipe; our GUI exited. */
		{
			wmcdda_close(cd_fd);
			wmaudio_close();
			exit(0);
		}

		if (FD_ISSET(0, &readfd))
		{
			/* If this doesn't work, just hope for the best */
			if(cd_fd == -1)
			    cd_fd = wmcdda_open(devname);
			cd_fd = command(cd_fd, &blockinfo);
			/*
			 * Process all commands in rapid succession, rather
			 * than possibly waiting for a CDDA read.
			 */
			continue;
		}
		
		if (playing)
		{
			result = wmcdda_read(cd_fd, cddabuf, cddabuflen,
				&blockinfo);
			if (result <= 0)
			{
				/* Let the output queue drain. */
				if (blockinfo.status == WMCDDA_DONE)
				{
					wmaudio_mark_last();
					if (wmaudio_send_status())
					{
						/* queue drained, stop polling*/
						playing = 0;
					}
				}
				else
				{
					playing = 0;
					send_status(&blockinfo);
				}
			}
			else
			{
				result = wmcdda_normalize(cddabuf, result,
							&blockinfo);
				result = wmcdda_transform(cddabuf, result,
							&blockinfo);
				if (output)
					fwrite(cddabuf, result, 1, output);
				result = wmaudio_convert(cddabuf, result,
							&blockinfo);
				if (wmaudio_play(cddabuf, result, &blockinfo))
				{
					playing = 0;
					wmaudio_stop();
					send_status(&blockinfo);
				}
			}
		}
		else
			send_status(&blockinfo);
	}
}

#else /* BUILD_CDDA */

main()
{
	exit(0);
}

#endif /* BUILD_CDDA */