ref: f6e4e5d887fdf935acbd7c1d00766014f099fc61
dir: /src/skel.c/
/*
* 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 "st_i.h"
/* Private data for SKEL file */
typedef struct skelstuff
{
st_size_t samples_remaining;
} *skel_t;
/*
* Do anything required before you start reading samples.
* Read file header.
* Find out sampling rate,
* size and encoding of samples,
* mono/stereo/quad.
*/
int st_skelstartread(ft_t ft)
{
skel_t sk = (skel_t) ft->priv;
/* If you need to seek around the input file. */
if (!ft->seekable)
{
st_fail_errno(ft,ST_EVALUE,"SKEL input file must be a file, not a pipe");
return (ST_EOF);
}
/*
* If your format is headerless and has fixed values for
* the following items, you can hard code them here (see cdr.c).
* If your format contains a header with format information
* then you should set it here.
*/
ft->info.rate = 44100L;
ft->info.size = ST_SIZE_BYTE or WORD ...;
ft->info.encoding = ST_ENCODING_UNSIGNED or SIGN2 ...;
ft->info.channels = 1 or 2 or 4;
ft->comment = malloc(size_of_comment);
strcpy(ft->comment, "any comment in file header.");
/* If your format doesn't have a header then samples_in_file
* can be determined by the file size.
*/
samples_in_file = st_filelength(ft)/ft->info.size;
/* If you can detect the length of your file, record it here. */
ft->length = samples_in_file;
sk->remaining_samples = samples_in_file;
return (ST_SUCCESS);
}
/*
* Read up to len samples from file.
* Convert to st_sample_t.
* Place in buf[].
* Return number of samples read.
*/
st_ssize_t st_skelread(ft_t ft, st_sample_t *buf, st_size_t len)
{
skel_t sk = (skel_t)ft->priv;
int done = 0;
st_sample_t l;
/* Always return a full frame of audio data */
if (len % ft->info.size)
len -= (len % ft->info.size);
for(; done < len; done++) {
if no more samples
break
get a sample
switch (ft->info.size)
{
case ST_SIZE_BYTE:
switch (ft->info.encoding)
{
case ST_ENCODING_UNSIGNED;
*buf++ = ST_UNSIGNED_BYTE_TO_SAMPLE(sample);
break;
}
break;
}
}
if (done == 0)
return ST_EOF;
else
return done;
}
/*
* Do anything required when you stop reading samples.
* Don't close input file!
*/
int skelstopread(ft_t ft)
{
return (ST_SUCCESS);
}
int st_skelstartwrite(ft_t ft)
{
skel_t sk = (skel_t) ft->priv;
/* If you have to seek around the output file. */
/* If header contains a length value then seeking will be
* required. Instead of failing, its sometimes nice to
* just set the length to max value and not fail.
*/
if (!ft->seekable)
{
st_fail_errno(ft, ST_EVALUE, "Output .skel file must be a file, not a pipe");
return (ST_EOF);
}
if (ft->info.rate != 44100L)
{
st_fail_errno(ft, ST_EVALUE, "Output. skel file must have a sample rate of 44100");
}
if (ft->info.size == -1)
{
st_fail_errno(ft, ST_EVALUE, "Did not specify a size for .skel output file");
return (ST_EOF);
}
error check ft->info.encoding;
error check ft->info.channels;
/* Write file header, if any */
/* Write comment field, if any */
return(ST_SUCCESS);
}
st_ssize_t st_skelwrite(ft_t ft, st_sample_t *buf, st_size_t len)
{
skel_t sk = (skel_t) ft->priv;
st_size_t len = 0;
switch (ft->info.size)
{
case ST_SIZE_BYTE:
switch (ft->info.encoding)
{
case ST_ENCODING_UNSIGNED:
while(len--)
{
len = st_writeb(ft, ST_SAMPLE_TO_UNSIGNED_BYTE(*buff++));
if (len == ST_EOF)
break;
}
break;
}
break;
}
if (len == ST_EOF)
return ST_EOF;
else
return ST_SUCCESS;
}
int st_skelstopwrite(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. */
return (ST_SUCCESS);
}