Sat Mar 10 01:54:17 2012

Asterisk developer's documentation


format_vox.c

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00001 /*
00002  * Asterisk -- An open source telephony toolkit.
00003  *
00004  * Copyright (C) 1999 - 2005, Digium, Inc.
00005  *
00006  * Mark Spencer <markster@digium.com>
00007  *
00008  * See http://www.asterisk.org for more information about
00009  * the Asterisk project. Please do not directly contact
00010  * any of the maintainers of this project for assistance;
00011  * the project provides a web site, mailing lists and IRC
00012  * channels for your use.
00013  *
00014  * This program is free software, distributed under the terms of
00015  * the GNU General Public License Version 2. See the LICENSE file
00016  * at the top of the source tree.
00017  */
00018 
00019 /*! \file
00020  *
00021  * \brief Flat, binary, ADPCM vox file format.
00022  * \arg File name extensions: vox
00023  * 
00024  * \ingroup formats
00025  */
00026 
00027 /*** MODULEINFO
00028    <support_level>extended</support_level>
00029  ***/
00030  
00031 #include "asterisk.h"
00032 
00033 ASTERISK_FILE_VERSION(__FILE__, "$Revision: 328209 $")
00034 
00035 #include "asterisk/mod_format.h"
00036 #include "asterisk/module.h"
00037 #include "asterisk/endian.h"
00038 
00039 #define BUF_SIZE  80    /* 80 bytes, 160 samples */
00040 #define VOX_SAMPLES  160
00041 
00042 static struct ast_frame *vox_read(struct ast_filestream *s, int *whennext)
00043 {
00044    int res;
00045 
00046    /* Send a frame from the file to the appropriate channel */
00047    s->fr.frametype = AST_FRAME_VOICE;
00048    s->fr.subclass.codec = AST_FORMAT_ADPCM;
00049    s->fr.mallocd = 0;
00050    AST_FRAME_SET_BUFFER(&s->fr, s->buf, AST_FRIENDLY_OFFSET, BUF_SIZE);
00051    if ((res = fread(s->fr.data.ptr, 1, s->fr.datalen, s->f)) < 1) {
00052       if (res)
00053          ast_log(LOG_WARNING, "Short read (%d) (%s)!\n", res, strerror(errno));
00054       return NULL;
00055    }
00056    *whennext = s->fr.samples = res * 2;
00057    s->fr.datalen = res;
00058    return &s->fr;
00059 }
00060 
00061 static int vox_write(struct ast_filestream *s, struct ast_frame *f)
00062 {
00063    int res;
00064    if (f->frametype != AST_FRAME_VOICE) {
00065       ast_log(LOG_WARNING, "Asked to write non-voice frame!\n");
00066       return -1;
00067    }
00068    if (f->subclass.codec != AST_FORMAT_ADPCM) {
00069       ast_log(LOG_WARNING, "Asked to write non-ADPCM frame (%s)!\n", ast_getformatname(f->subclass.codec));
00070       return -1;
00071    }
00072    if ((res = fwrite(f->data.ptr, 1, f->datalen, s->f)) != f->datalen) {
00073          ast_log(LOG_WARNING, "Bad write (%d/%d): %s\n", res, f->datalen, strerror(errno));
00074          return -1;
00075    }
00076    return 0;
00077 }
00078 
00079 static int vox_seek(struct ast_filestream *fs, off_t sample_offset, int whence)
00080 {
00081      off_t offset=0,min,cur,max,distance;
00082    
00083      min = 0;
00084      cur = ftello(fs->f);
00085      fseeko(fs->f, 0, SEEK_END);
00086     max = ftello(fs->f);
00087     
00088      /* have to fudge to frame here, so not fully to sample */
00089      distance = sample_offset/2;
00090      if(whence == SEEK_SET)
00091      offset = distance;
00092      else if(whence == SEEK_CUR || whence == SEEK_FORCECUR)
00093      offset = distance + cur;
00094      else if(whence == SEEK_END)
00095      offset = max - distance;
00096      if (whence != SEEK_FORCECUR) {
00097      offset = (offset > max)?max:offset;
00098      offset = (offset < min)?min:offset;
00099      }
00100      return fseeko(fs->f, offset, SEEK_SET);
00101 }
00102 
00103 static int vox_trunc(struct ast_filestream *fs)
00104 {
00105      return ftruncate(fileno(fs->f), ftello(fs->f));
00106 }
00107 
00108 static off_t vox_tell(struct ast_filestream *fs)
00109 {
00110      off_t offset;
00111      offset = ftello(fs->f) << 1;
00112      return offset; 
00113 }
00114 
00115 static const struct ast_format vox_f = {
00116    .name = "vox",
00117    .exts = "vox",
00118    .format = AST_FORMAT_ADPCM,
00119    .write = vox_write,
00120    .seek = vox_seek,
00121    .trunc = vox_trunc,
00122    .tell = vox_tell,
00123    .read = vox_read,
00124    .buf_size = BUF_SIZE + AST_FRIENDLY_OFFSET,
00125 };
00126 
00127 static int load_module(void)
00128 {
00129    if (ast_format_register(&vox_f))
00130       return AST_MODULE_LOAD_FAILURE;
00131    return AST_MODULE_LOAD_SUCCESS;
00132 }
00133 
00134 static int unload_module(void)
00135 {
00136    return ast_format_unregister(vox_f.name);
00137 }
00138 
00139 AST_MODULE_INFO(ASTERISK_GPL_KEY, AST_MODFLAG_LOAD_ORDER, "Dialogic VOX (ADPCM) File Format",
00140    .load = load_module,
00141    .unload = unload_module,
00142    .load_pri = AST_MODPRI_APP_DEPEND
00143 );

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