format_g723.c

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/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 1999 - 2005, Digium, Inc.
 *
 * Mark Spencer <[email protected]>
 *
 * 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      /* Out of data, or the file is no longer valid.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
);