format_vox.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 Flat, binary, ADPCM vox file format.
 * \arg File name extensions: vox
 * 
 * \ingroup formats
 */
 
#include "asterisk.h"

ASTERISK_FILE_VERSION(__FILE__, "$Revision: 117802 $")

#include "asterisk/mod_format.h"
#include "asterisk/module.h"
#include "asterisk/endian.h"

#define BUF_SIZE  80    /* 80 bytes, 160 samples */
#define VOX_SAMPLES  160

static struct ast_frame *vox_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_ADPCM;
   s->fr.mallocd = 0;
   AST_FRAME_SET_BUFFER(&s->fr, s->buf, AST_FRIENDLY_OFFSET, BUF_SIZE);
   if ((res = fread(s->fr.data.ptr, 1, s->fr.datalen, s->f)) < 1) {
      if (res)
         ast_log(LOG_WARNING, "Short read (%d) (%s)!\n", res, strerror(errno));
      return NULL;
   }
   *whennext = s->fr.samples = res * 2;
   s->fr.datalen = res;
   return &s->fr;
}

static int vox_write(struct ast_filestream *s, struct ast_frame *f)
{
   int res;
   if (f->frametype != AST_FRAME_VOICE) {
      ast_log(LOG_WARNING, "Asked to write non-voice frame!\n");
      return -1;
   }
   if (f->subclass != AST_FORMAT_ADPCM) {
      ast_log(LOG_WARNING, "Asked to write non-ADPCM frame (%d)!\n", f->subclass);
      return -1;
   }
   if ((res = fwrite(f->data.ptr, 1, f->datalen, s->f)) != f->datalen) {
         ast_log(LOG_WARNING, "Bad write (%d/%d): %s\n", res, f->datalen, strerror(errno));
         return -1;
   }
   return 0;
}

static int vox_seek(struct ast_filestream *fs, off_t sample_offset, int whence)
{
     off_t offset=0,min,cur,max,distance;
   
     min = 0;
     cur = ftello(fs->f);
     fseeko(fs->f, 0, SEEK_END);
    max = ftello(fs->f);
    
     /* have to fudge to frame here, so not fully to sample */
     distance = sample_offset/2;
     if(whence == SEEK_SET)
     offset = distance;
     else if(whence == SEEK_CUR || whence == SEEK_FORCECUR)
     offset = distance + cur;
     else if(whence == SEEK_END)
     offset = max - distance;
     if (whence != SEEK_FORCECUR) {
     offset = (offset > max)?max:offset;
     offset = (offset < min)?min:offset;
     }
     return fseeko(fs->f, offset, SEEK_SET);
}

static int vox_trunc(struct ast_filestream *fs)
{
     return ftruncate(fileno(fs->f), ftello(fs->f));
}

static off_t vox_tell(struct ast_filestream *fs)
{
     off_t offset;
     offset = ftello(fs->f) << 1;
     return offset; 
}

static const struct ast_format vox_f = {
   .name = "vox",
   .exts = "vox",
   .format = AST_FORMAT_ADPCM,
   .write = vox_write,
   .seek = vox_seek,
   .trunc = vox_trunc,
   .tell = vox_tell,
   .read = vox_read,
   .buf_size = BUF_SIZE + AST_FRIENDLY_OFFSET,
};

static int load_module(void)
{
   if (ast_format_register(&vox_f))
      return AST_MODULE_LOAD_FAILURE;
   return AST_MODULE_LOAD_SUCCESS;
}

static int unload_module(void)
{
   return ast_format_unregister(vox_f.name);
}  

AST_MODULE_INFO_STANDARD(ASTERISK_GPL_KEY, "Dialogic VOX (ADPCM) File Format");