skel.c

linux下录音程序

/*
 * July 5, 1991
 * Copyright 1991 Lance Norskog And Sundry Contributors
 * This source code is freely redistributable and may be used for
 * any purpose.  This copyright notice must be maintained. 
 * Lance Norskog And Sundry Contributors are not responsible for 
 * the consequences of using this software.
 */

/*
 * Sound Tools skeleton file format driver.
 */

#include <math.h>
#include "st.h"

/* Private data for SKEL file */
typedef struct skelstuff {
	int	rest;			/* bytes remaining in current block */
} *skel_t;

/*
 * Do anything required before you start reading samples.
 * Read file header. 
 *	Find out sampling rate, 
 *	size and style of samples, 
 *	mono/stereo/quad.
 */
skelstartread(ft) 
ft_t ft;
{
	skel_t sk = (skel_t) ft->priv;

	/* If you need to seek around the input file. */
	if (! ft->seekable)
		fail("SKEL input file must be a file, not a pipe");

	/*
	 * If your format specifies or your file header contains
	 * any of the following information. 
	 */
	ft->info.rate = 
	ft->info.size = BYTE or WORD ...;
	ft->info.style = UNSIGNED or SIGN2 ...;
	ft->info.channels = 1 or 2 or 4;
	ft->comment = any comment in file header.
}

/*
 * Read up to len samples from file.
 * Convert to signed longs.
 * Place in buf[].
 * Return number of samples read.
 */

skelread(ft, buf, len) 
ft_t ft;
LONG *buf, len;
{
	skel_t sk = (skel_t) ft->priv;
	int abs;
	float amp;
	int done = 0;
	
	char c;
	unsigned char uc;
	short s;
	unsigned short us;
	LONG l;
	ULONG ul;
	float f;
	double d;

	for(; done < len; done++) {
		if no more samples
			break
		get a sample
		l = sample converted to signed long
		*buf++ = l;
	}
	return done;
}

/*
 * Do anything required when you stop reading samples.  
 * Don't close input file! 
 */
skelstopread(ft) 
ft_t ft;
{
}

skelstartwrite(ft) 
ft_t ft;
{
	skel_t sk = (skel_t) ft->priv;

	/* If you have to seek around the output file */
	if (! ft->seekable)
		fail("Output .skel file must be a file, not a pipe");

	/* If your format specifies any of the following info. */
	ft->info.rate = 
	ft->info.size = BYTE or WORD ...;
	ft->info.style = UNSIGNED or SIGN2 ...;
	ft->info.channels = 1 or 2 or 4;
	/* Write file header, if any */
	/* Write comment field, if any */
	
}

skelwrite(ft, buf, len) 
ft_t ft;
LONG *buf, len;
{
	skel_t sk = (skel_t) ft->priv;
	register int datum;
	int abs;
	int done = 0;

	while(len--)
		putc((*buf++ >> 24) ^ 0x80, ft->fp);
	/* If you cannot write out all of the supplied samples, */
	/*	fail("SKEL: Can't write all samples to %s", ft->filename); */
	
}

skelstopwrite(ft) 
ft_t ft;
{
	/* All samples are already written out. */
	/* If file header needs fixing up, for example it needs the */
 	/* the number of samples in a field, seek back and write them here. */
}