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asterisk/formats/format_pcm_alaw.c

292 lines
6.5 KiB

/*
* Asterisk -- An open source telephony toolkit.
*
* Copyright (C) 1999 - 2006, Digium, Inc.
*
* Mark Spencer <markster@digium.com>
*
* See http://www.asterisk.org for more information about
* the Asterisk project. Please do not directly contact
* any of the maintainers of this project for assistance;
* the project provides a web site, mailing lists and IRC
* channels for your use.
*
* This program is free software, distributed under the terms of
* the GNU General Public License Version 2. See the LICENSE file
* at the top of the source tree.
*/
/*! \file
*
* \brief Flat, binary, alaw PCM file format.
* \arg File name extensions: alaw, al
* \ingroup formats
*/
#include <unistd.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <stdlib.h>
#include <sys/time.h>
#include <sys/times.h>
#include <sys/types.h>
#include <stdio.h>
#include <errno.h>
#include <string.h>
#include "asterisk.h"
ASTERISK_FILE_VERSION(__FILE__, "$Revision$")
#include "asterisk/lock.h"
#include "asterisk/channel.h"
#include "asterisk/file.h"
#include "asterisk/logger.h"
#include "asterisk/sched.h"
#include "asterisk/module.h"
#include "asterisk/endian.h"
#include "asterisk/alaw.h"
#define BUF_SIZE 160 /* 160 bytes, and same number of samples */
/* #define REALTIME_WRITE */ /* XXX does it work at all ? */
struct pcma_desc {
#ifdef REALTIME_WRITE
unsigned long start_time;
#endif
};
static char alaw_silence[BUF_SIZE];
#if 0
/* Returns time in msec since system boot. */
static unsigned long get_time(struct ast_filestream *s)
{
struct tms buf;
clock_t cur;
unsigned long *res;
cur = times( &buf );
if( cur < 0 )
{
ast_log( LOG_WARNING, "Cannot get current time\n" );
return 0;
}
res = cur * 1000 / sysconf( _SC_CLK_TCK );
if (s) {
struct pcma_desc *d = (struct pcma_filestream *)s->private;
d->start_time = res;
}
return res;
}
#endif
static int pcm_open(struct ast_filestream *s)
{
#ifdef REALTIME_WRITE
get_time(s);
#endif
return 0;
}
static int pcm_rewrite(struct ast_filestream *s, const char *comment)
{
return pcm_open(s);
}
static struct ast_frame *pcm_read(struct ast_filestream *s, int *whennext)
{
int res;
/* Send a frame from the file to the appropriate channel */
s->fr.frametype = AST_FRAME_VOICE;
s->fr.subclass = AST_FORMAT_ALAW;
s->fr.mallocd = 0;
FR_SET_BUF(&s->fr, s->buf, AST_FRIENDLY_OFFSET, BUF_SIZE);
if ((res = fread(s->fr.data, 1, s->fr.datalen, s->f)) < 1) {
if (res)
ast_log(LOG_WARNING, "Short read (%d) (%s)!\n", res, strerror(errno));
return NULL;
}
s->fr.datalen = res;
*whennext = s->fr.samples = res;
return &s->fr;
}
static int pcm_write(struct ast_filestream *fs, struct ast_frame *f)
{
int res;
#ifdef REALTIME_WRITE
unsigned long cur_time;
unsigned long fpos;
struct stat stat_buf;
struct pcma_filestream *s = (struct pcma_filestream *)fs->private;
#endif
if (f->frametype != AST_FRAME_VOICE) {
ast_log(LOG_WARNING, "Asked to write non-voice frame!\n");
return -1;
}
if (f->subclass != AST_FORMAT_ALAW) {
ast_log(LOG_WARNING, "Asked to write non-alaw frame (%d)!\n", f->subclass);
return -1;
}
#ifdef REALTIME_WRITE
cur_time = get_time();
fpos = ( cur_time - s->start_time ) * 8; /* 8 bytes per msec */
/* Check if we have written to this position yet. If we have, then increment pos by one frame
* for some degree of protection against receiving packets in the same clock tick.
*/
fstat(fileno(fs->f), &stat_buf );
if (stat_buf.st_size > fpos ) {
fpos += f->datalen; /* Incrementing with the size of this current frame */
}
if (stat_buf.st_size < fpos) {
/* fill the gap with 0x55 rather than 0. */
char buf[ 512 ];
unsigned long cur, to_write;
cur = stat_buf.st_size;
if (fseeko(fs->f, cur, SEEK_SET) < 0) {
ast_log( LOG_WARNING, "Cannot seek in file: %s\n", strerror(errno) );
return -1;
}
memset(buf, 0x55, 512);
while (cur < fpos) {
to_write = fpos - cur;
if (to_write > 512) {
to_write = 512;
}
fwrite(buf, 1, to_write, fs->f);
cur += to_write;
}
}
if (fseeko(s->f, fpos, SEEK_SET) < 0) {
ast_log( LOG_WARNING, "Cannot seek in file: %s\n", strerror(errno) );
return -1;
}
#endif /* REALTIME_WRITE */
if ((res = fwrite(f->data, 1, f->datalen, fs->f)) != f->datalen) {
ast_log(LOG_WARNING, "Bad write (%d/%d): %s\n", res, f->datalen, strerror(errno));
return -1;
}
return 0;
}
static int pcm_seek(struct ast_filestream *fs, off_t sample_offset, int whence)
{
off_t cur, max, offset = 0;
int ret = -1; /* assume error */
cur = ftello(fs->f);
fseeko(fs->f, 0, SEEK_END);
max = ftello(fs->f);
switch (whence) {
case SEEK_SET:
offset = sample_offset;
break;
case SEEK_END:
offset = max - sample_offset;
break;
case SEEK_CUR:
case SEEK_FORCECUR:
offset = cur + sample_offset;
break;
default:
ast_log(LOG_WARNING, "invalid whence %d, assuming SEEK_SET\n", whence);
offset = sample_offset;
}
if (offset < 0) {
offset = 0;
ast_log(LOG_WARNING, "negative offset %ld, resetting to 0\n", (long) offset);
}
if (whence == SEEK_FORCECUR && offset > max) {
size_t left = offset - max;
while (left) {
size_t written = fwrite(alaw_silence, sizeof(alaw_silence[0]),
(left > BUF_SIZE) ? BUF_SIZE : left, fs->f);
if (written == -1)
break; /* error */
left -= written * sizeof(alaw_silence[0]);
}
ret = 0; /* success */
} else {
if (offset > max) {
ast_log(LOG_WARNING, "offset too large %ld, truncating to %ld\n", (long) offset, (long) max);
offset = max;
}
ret = fseeko(fs->f, offset, SEEK_SET);
}
return ret;
}
static int pcm_trunc(struct ast_filestream *fs)
{
return ftruncate(fileno(fs->f), ftello(fs->f));
}
static off_t pcm_tell(struct ast_filestream *fs)
{
return ftello(fs->f);
}
static struct ast_format_lock me = { .usecnt = -1 };
static const struct ast_format alaw_f = {
.name = "alaw",
.exts = "alaw|al",
.format = AST_FORMAT_ALAW,
.open = pcm_open,
.rewrite = pcm_rewrite,
.write = pcm_write,
.seek = pcm_seek,
.trunc = pcm_trunc,
.tell = pcm_tell,
.read = pcm_read,
.buf_size = BUF_SIZE + AST_FRIENDLY_OFFSET,
.lockp = &me,
#ifdef REALTIME_WRITE
.desc_size = sizeof(struct pcma_desc),
#endif
};
int load_module()
{
int index;
for (index = 0; index < (sizeof(alaw_silence) / sizeof(alaw_silence[0])); index++)
alaw_silence[index] = AST_LIN2A(0);
return ast_format_register(&alaw_f);
}
int unload_module()
{
return ast_format_unregister(alaw_f.name);
}
int usecount()
{
return me.usecnt;
}
char *description()
{
return "Raw aLaw 8khz PCM Audio support";
}
char *key()
{
return ASTERISK_GPL_KEY;
}