format_g723.c

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/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 1999 - 2005, 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 Old-style G.723.1 frame/timestamp format.
 *
 * \arg Extensions: g723, g723sf
 * \ingroup formats
 */
 
/*** MODULEINFO
    <support_level>core</support_level>
 ***/
 
#include "asterisk.h"
 
#include "asterisk/mod_format.h"
#include "asterisk/module.h"
#include "asterisk/format_cache.h"
 
#define G723_MAX_SIZE 1024
 
static struct ast_frame *g723_read(struct ast_filestream *s, int *whennext)
{
    unsigned short size;
    size_t res;
    int delay;
    /* Read the delay for the next packet, and schedule again if necessary */
    /* XXX is this ignored ? */
    if (fread(&delay, 1, 4, s->f) == 4)
        delay = ntohl(delay);
    else
        delay = -1;
    if (fread(&size, 1, 2, s->f) != 2) {
        /* Out of data, or the file is no longer valid.  In any case
           go ahead and stop the stream */
        return NULL;
    }
    /* Looks like we have a frame to read from here */
    size = ntohs(size);
    if (size > G723_MAX_SIZE) {
        ast_log(LOG_WARNING, "Size %d is invalid\n", size);
        /* The file is apparently no longer any good, as we
           shouldn't ever get frames even close to this
           size.  */
        return NULL;
    }
    /* Read the data into the buffer */
    AST_FRAME_SET_BUFFER(&s->fr, s->buf, AST_FRIENDLY_OFFSET, size);
    if ((res = fread(s->fr.data.ptr, 1, s->fr.datalen, s->f)) != s->fr.datalen) {
        if (res) {
            ast_log(LOG_WARNING, "Short read of %s data (expected %d bytes, read %zu): %s\n",
                    ast_format_get_name(s->fr.subclass.format), s->fr.datalen, res,
                    strerror(errno));
        }
        return NULL;
    }
    *whennext = s->fr.samples = 240;
    return &s->fr;
}
 
static int g723_write(struct ast_filestream *s, struct ast_frame *f)
{
    uint32_t delay;
    uint16_t size;
    int res;
    /* XXX there used to be a check s->fr means a read stream */
    delay = 0;
    if (f->datalen <= 0) {
        ast_log(LOG_WARNING, "Short frame ignored (%d bytes long?)\n", f->datalen);
        return 0;
    }
    if ((res = fwrite(&delay, 1, 4, s->f)) != 4) {
        ast_log(LOG_WARNING, "Unable to write delay: res=%d (%s)\n", res, strerror(errno));
        return -1;
    }
    size = htons(f->datalen);
    if ((res = fwrite(&size, 1, 2, s->f)) != 2) {
        ast_log(LOG_WARNING, "Unable to write size: res=%d (%s)\n", res, strerror(errno));
        return -1;
    }
    if ((res = fwrite(f->data.ptr, 1, f->datalen, s->f)) != f->datalen) {
        ast_log(LOG_WARNING, "Unable to write frame: res=%d (%s)\n", res, strerror(errno));
        return -1;
    }
    return 0;
}
 
static int g723_seek(struct ast_filestream *fs, off_t sample_offset, int whence)
{
    return -1;
}
 
static int g723_trunc(struct ast_filestream *fs)
{
    int fd;
    off_t cur;
 
    if ((fd = fileno(fs->f)) < 0) {
        ast_log(AST_LOG_WARNING, "Unable to determine file descriptor for g723 filestream %p: %s\n", fs, strerror(errno));
        return -1;
    }
    if ((cur = ftello(fs->f)) < 0) {
        ast_log(AST_LOG_WARNING, "Unable to determine current position in g723 filestream %p: %s\n", fs, strerror(errno));
        return -1;
    }
    /* Truncate file to current length */
    return ftruncate(fd, cur);
}
 
static off_t g723_tell(struct ast_filestream *fs)
{
    return -1;
}
 
static struct ast_format_def g723_1_f = {
    .name = "g723sf",
    .exts = "g723|g723sf",
    .write = g723_write,
    .seek = g723_seek,
    .trunc = g723_trunc,
    .tell = g723_tell,
    .read = g723_read,
    .buf_size = G723_MAX_SIZE + AST_FRIENDLY_OFFSET,
};
 
static int load_module(void)
{
    g723_1_f.format = ast_format_g723;
 
    if (ast_format_def_register(&g723_1_f))
        return AST_MODULE_LOAD_DECLINE;
    return AST_MODULE_LOAD_SUCCESS;
}
 
static int unload_module(void)
{
    return ast_format_def_unregister(g723_1_f.name);
}
 
AST_MODULE_INFO(ASTERISK_GPL_KEY, AST_MODFLAG_LOAD_ORDER, "G.723.1 Simple Timestamp File Format",
    .support_level = AST_MODULE_SUPPORT_CORE,
    .load = load_module,
    .unload = unload_module,
    .load_pri = AST_MODPRI_APP_DEPEND
);