ref: 9abe8822ba60526b4f02fb0fbf4634f4eb9bf51d
dir: /src/skelform.c/
/* libSoX skeleton file format handler.
*
* Copyright 1999 Chris Bagwell And Sundry Contributors
*
* This library is free software; you can redistribute it and/or modify it
* under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation; either version 2.1 of the License, or (at
* your option) any later version.
*
* This library 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 Lesser
* General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this library; if not, write to the Free Software Foundation,
* Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include "sox_i.h"
#include <string.h>
/* Private data for SKEL file */
typedef struct {
size_t remaining_samples;
} priv_t;
/* Note that if any of your methods doesn't need to do anything, you
can instead use the relevant sox_*_nothing* method */
/*
* Do anything required before you start reading samples.
* Read file header.
* Find out sampling rate,
* size and encoding of samples,
* mono/stereo/quad.
*/
static int startread(sox_format_t * ft)
{
priv_t * sk = (priv_t *)ft->priv;
size_t samples_in_file;
/* If you need to seek around the input file. */
if (!ft->seekable) {
lsx_fail_errno(ft, SOX_EOF, "skel inputfile must be a file");
return SOX_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->signal.rate = 44100; /* or 8000, 16000, 32000, 48000, ... */
ft->signal.channels = 1; /* or 2 or 3 ... */
ft->encoding.bits_per_sample = 8; /* or 16 ... */
ft->encoding.encoding = SOX_ENCODING_UNSIGNED; /* or SIGN2 ... */
sox_append_comment(&ft->oob.comments, "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 = lsx_filelength(ft) / (ft->encoding.bits_per_sample >> 3);
/* If you can detect the length of your file, record it here. */
ft->signal.length = samples_in_file;
sk->remaining_samples = samples_in_file;
return SOX_SUCCESS;
}
/*
* Read up to len samples of type sox_sample_t from file into buf[].
* Return number of samples read, or 0 if at end of file.
*/
static size_t read_samples(sox_format_t * ft, sox_sample_t *buf, size_t len)
{
priv_t * UNUSED sk = (priv_t *)ft->priv;
size_t done;
unsigned char sample;
for (done = 0; done < len; done++) {
if (lsx_eof(ft) || lsx_readb(ft, &sample)) /* no more samples */
break;
switch (ft->encoding.bits_per_sample) {
case 8:
switch (ft->encoding.encoding) {
case SOX_ENCODING_UNSIGNED:
*buf++ = SOX_UNSIGNED_8BIT_TO_SAMPLE(sample,);
break;
default:
lsx_fail("Undetected sample encoding in read!");
return 0;
}
break;
default:
lsx_fail("Undetected bad sample size in read!");
return 0;
}
}
return done;
}
/*
* Do anything required when you stop reading samples.
* Don't close input file!
*/
static int stopread(sox_format_t UNUSED * ft)
{
return SOX_SUCCESS;
}
static int startwrite(sox_format_t * ft)
{
priv_t * UNUSED sk = (priv_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, it's sometimes nice to
* just set the length to max value and not fail.
*/
if (!ft->seekable) {
lsx_fail("Output .skel file must be a file, not a pipe");
return SOX_EOF;
}
if (ft->signal.rate != 44100)
lsx_fail("Output .skel file must have a sample rate of 44100Hz");
if (ft->encoding.bits_per_sample == 0) {
lsx_fail("Did not specify a size for .skel output file");
return SOX_EOF;
}
/* error check ft->encoding.encoding */
/* error check ft->signal.channels */
/* Write file header, if any */
/* Write comment field, if any */
return SOX_SUCCESS;
}
/*
* Write len samples of type sox_sample_t from buf[] to file.
* Return number of samples written.
*/
static size_t write_samples(sox_format_t * ft, const sox_sample_t *buf, size_t len)
{
priv_t * sk = (priv_t *)ft->priv;
size_t done = 0;
(void)sk;
switch (ft->encoding.bits_per_sample) {
case 8:
switch (ft->encoding.encoding) {
SOX_SAMPLE_LOCALS;
case SOX_ENCODING_UNSIGNED:
while (done < len && lsx_writeb(ft, SOX_SAMPLE_TO_UNSIGNED_8BIT(*buf++, ft->clips)) == SOX_SUCCESS)
++done;
break;
default:
lsx_fail("Undetected bad sample encoding in write!");
return 0;
}
break;
default:
lsx_fail("Undetected bad sample size in write!");
return 0;
}
return done;
}
static int stopwrite(sox_format_t UNUSED * ft)
{
/* All samples are already written out. */
/* If file header needs fixing up, for example it needs the number
of samples in a field, seek back and write them here. */
return SOX_SUCCESS;
}
static int seek(sox_format_t UNUSED * ft, uint64_t UNUSED offset)
{
/* Seek relative to current position. */
return SOX_SUCCESS;
}
LSX_FORMAT_HANDLER(skel)
{
/* Format file suffixes */
static const char *names[] = {"skel",NULL };
/* Encoding types and sizes that this handler can write */
static const unsigned encodings[] = {
SOX_ENCODING_SIGN2, 16, 0,
SOX_ENCODING_UNSIGNED, 8, 0,
0};
/* Format descriptor
* If no specific processing is needed for any of
* the 7 functions, then the function above can be deleted
* and NULL used in place of the its name below.
*/
static sox_format_handler_t handler = {
SOX_LIB_VERSION_CODE,
"My first SoX format!",
names, 0,
startread, read_samples, stopread,
startwrite, write_samples, stopwrite,
seek, encodings, NULL, sizeof(priv_t)
};
return &handler;
}