Sat Aug 6 00:39:28 2011

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 #include "asterisk.h"
00028 
00029 ASTERISK_FILE_VERSION(__FILE__, "$Revision: 233782 $")
00030 
00031 #include <unistd.h>
00032 #include <netinet/in.h>
00033 #include <arpa/inet.h>
00034 #include <stdlib.h>
00035 #include <sys/time.h>
00036 #include <stdio.h>
00037 #include <errno.h>
00038 #include <string.h>
00039 
00040 #include "asterisk/lock.h"
00041 #include "asterisk/channel.h"
00042 #include "asterisk/file.h"
00043 #include "asterisk/logger.h"
00044 #include "asterisk/sched.h"
00045 #include "asterisk/module.h"
00046 #include "asterisk/endian.h"
00047 
00048 #define BUF_SIZE  80    /* 80 bytes, 160 samples */
00049 #define VOX_SAMPLES  160
00050 
00051 static struct ast_frame *vox_read(struct ast_filestream *s, int *whennext)
00052 {
00053    int res;
00054 
00055    /* Send a frame from the file to the appropriate channel */
00056    s->fr.frametype = AST_FRAME_VOICE;
00057    s->fr.subclass = AST_FORMAT_ADPCM;
00058    s->fr.mallocd = 0;
00059    AST_FRAME_SET_BUFFER(&s->fr, s->buf, AST_FRIENDLY_OFFSET, BUF_SIZE);
00060    if ((res = fread(s->fr.data, 1, s->fr.datalen, s->f)) < 1) {
00061       if (res)
00062          ast_log(LOG_WARNING, "Short read (%d) (%s)!\n", res, strerror(errno));
00063       return NULL;
00064    }
00065    *whennext = s->fr.samples = res * 2;
00066    s->fr.datalen = res;
00067    return &s->fr;
00068 }
00069 
00070 static int vox_write(struct ast_filestream *s, struct ast_frame *f)
00071 {
00072    int res;
00073    if (f->frametype != AST_FRAME_VOICE) {
00074       ast_log(LOG_WARNING, "Asked to write non-voice frame!\n");
00075       return -1;
00076    }
00077    if (f->subclass != AST_FORMAT_ADPCM) {
00078       ast_log(LOG_WARNING, "Asked to write non-ADPCM frame (%d)!\n", f->subclass);
00079       return -1;
00080    }
00081    if ((res = fwrite(f->data, 1, f->datalen, s->f)) != f->datalen) {
00082          ast_log(LOG_WARNING, "Bad write (%d/%d): %s\n", res, f->datalen, strerror(errno));
00083          return -1;
00084    }
00085    return 0;
00086 }
00087 
00088 static int vox_seek(struct ast_filestream *fs, off_t sample_offset, int whence)
00089 {
00090      off_t offset=0,min,cur,max,distance;
00091    
00092      min = 0;
00093      cur = ftello(fs->f);
00094      fseeko(fs->f, 0, SEEK_END);
00095     max = ftello(fs->f);
00096     
00097      /* have to fudge to frame here, so not fully to sample */
00098      distance = sample_offset/2;
00099      if(whence == SEEK_SET)
00100      offset = distance;
00101      else if(whence == SEEK_CUR || whence == SEEK_FORCECUR)
00102      offset = distance + cur;
00103      else if(whence == SEEK_END)
00104      offset = max - distance;
00105      if (whence != SEEK_FORCECUR) {
00106      offset = (offset > max)?max:offset;
00107      offset = (offset < min)?min:offset;
00108      }
00109      return fseeko(fs->f, offset, SEEK_SET);
00110 }
00111 
00112 static int vox_trunc(struct ast_filestream *fs)
00113 {
00114      return ftruncate(fileno(fs->f), ftello(fs->f));
00115 }
00116 
00117 static off_t vox_tell(struct ast_filestream *fs)
00118 {
00119      off_t offset;
00120      offset = ftello(fs->f) << 1;
00121      return offset; 
00122 }
00123 
00124 static const struct ast_format vox_f = {
00125    .name = "vox",
00126    .exts = "vox",
00127    .format = AST_FORMAT_ADPCM,
00128    .write = vox_write,
00129    .seek = vox_seek,
00130    .trunc = vox_trunc,
00131    .tell = vox_tell,
00132    .read = vox_read,
00133    .buf_size = BUF_SIZE + AST_FRIENDLY_OFFSET,
00134 };
00135 
00136 static int load_module(void)
00137 {
00138    return ast_format_register(&vox_f);
00139 }
00140 
00141 static int unload_module(void)
00142 {
00143    return ast_format_unregister(vox_f.name);
00144 }  
00145 
00146 AST_MODULE_INFO(ASTERISK_GPL_KEY, AST_MODFLAG_LOAD_FIRST, "Dialogic VOX (ADPCM) File Format",
00147    .load = load_module,
00148    .unload = unload_module,
00149 );

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