Sat Aug 6 00:39:28 2011

Asterisk developer's documentation


format_ilbc.c

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00001 /*
00002  * Asterisk -- An open source telephony toolkit.
00003  *
00004  * Brian K. West <brian@bkw.org>
00005  * 
00006  * Copyright (C) 1999 - 2005, Digium, Inc.
00007  *
00008  * Mark Spencer <markster@digium.com>
00009  *
00010  * See http://www.asterisk.org for more information about
00011  * the Asterisk project. Please do not directly contact
00012  * any of the maintainers of this project for assistance;
00013  * the project provides a web site, mailing lists and IRC
00014  * channels for your use.
00015  *
00016  * This program is free software, distributed under the terms of
00017  * the GNU General Public License Version 2. See the LICENSE file
00018  * at the top of the source tree.
00019  */
00020 
00021 /*! \file
00022  *
00023  * \brief Save to raw, headerless iLBC data.
00024  * \arg File name extension: ilbc
00025  * \ingroup formats
00026  */
00027 
00028 #include "asterisk.h"
00029 
00030 ASTERISK_FILE_VERSION(__FILE__, "$Revision: 233782 $")
00031 
00032 #include <unistd.h>
00033 #include <netinet/in.h>
00034 #include <arpa/inet.h>
00035 #include <stdlib.h>
00036 #include <sys/time.h>
00037 #include <stdio.h>
00038 #include <errno.h>
00039 #include <string.h>
00040 
00041 #include "asterisk/lock.h"
00042 #include "asterisk/channel.h"
00043 #include "asterisk/file.h"
00044 #include "asterisk/logger.h"
00045 #include "asterisk/sched.h"
00046 #include "asterisk/module.h"
00047 #include "asterisk/endian.h"
00048 
00049 /* Some Ideas for this code came from makeg729e.c by Jeffrey Chilton */
00050 
00051 /* Portions of the conversion code are by guido@sienanet.it */
00052 
00053 #define  ILBC_BUF_SIZE  50 /* One Real iLBC Frame */
00054 #define  ILBC_SAMPLES   240
00055 
00056 static struct ast_frame *ilbc_read(struct ast_filestream *s, int *whennext)
00057 {
00058    int res;
00059    /* Send a frame from the file to the appropriate channel */
00060    s->fr.frametype = AST_FRAME_VOICE;
00061    s->fr.subclass = AST_FORMAT_ILBC;
00062    s->fr.mallocd = 0;
00063    AST_FRAME_SET_BUFFER(&s->fr, s->buf, AST_FRIENDLY_OFFSET, ILBC_BUF_SIZE);
00064    if ((res = fread(s->fr.data, 1, s->fr.datalen, s->f)) != s->fr.datalen) {
00065       if (res)
00066          ast_log(LOG_WARNING, "Short read (%d) (%s)!\n", res, strerror(errno));
00067       return NULL;
00068    }
00069    *whennext = s->fr.samples = ILBC_SAMPLES;
00070    return &s->fr;
00071 }
00072 
00073 static int ilbc_write(struct ast_filestream *fs, struct ast_frame *f)
00074 {
00075    int res;
00076    if (f->frametype != AST_FRAME_VOICE) {
00077       ast_log(LOG_WARNING, "Asked to write non-voice frame!\n");
00078       return -1;
00079    }
00080    if (f->subclass != AST_FORMAT_ILBC) {
00081       ast_log(LOG_WARNING, "Asked to write non-iLBC frame (%d)!\n", f->subclass);
00082       return -1;
00083    }
00084    if (f->datalen % 50) {
00085       ast_log(LOG_WARNING, "Invalid data length, %d, should be multiple of 50\n", f->datalen);
00086       return -1;
00087    }
00088    if ((res = fwrite(f->data, 1, f->datalen, fs->f)) != f->datalen) {
00089          ast_log(LOG_WARNING, "Bad write (%d/50): %s\n", res, strerror(errno));
00090          return -1;
00091    }
00092    return 0;
00093 }
00094 
00095 static int ilbc_seek(struct ast_filestream *fs, off_t sample_offset, int whence)
00096 {
00097    long bytes;
00098    off_t min,cur,max,offset=0;
00099    min = 0;
00100    cur = ftello(fs->f);
00101    fseeko(fs->f, 0, SEEK_END);
00102    max = ftello(fs->f);
00103    
00104    bytes = ILBC_BUF_SIZE * (sample_offset / ILBC_SAMPLES);
00105    if (whence == SEEK_SET)
00106       offset = bytes;
00107    else if (whence == SEEK_CUR || whence == SEEK_FORCECUR)
00108       offset = cur + bytes;
00109    else if (whence == SEEK_END)
00110       offset = max - bytes;
00111    if (whence != SEEK_FORCECUR) {
00112       offset = (offset > max)?max:offset;
00113    }
00114    /* protect against seeking beyond begining. */
00115    offset = (offset < min)?min:offset;
00116    if (fseeko(fs->f, offset, SEEK_SET) < 0)
00117       return -1;
00118    return 0;
00119 }
00120 
00121 static int ilbc_trunc(struct ast_filestream *fs)
00122 {
00123    /* Truncate file to current length */
00124    if (ftruncate(fileno(fs->f), ftello(fs->f)) < 0)
00125       return -1;
00126    return 0;
00127 }
00128 
00129 static off_t ilbc_tell(struct ast_filestream *fs)
00130 {
00131    off_t offset = ftello(fs->f);
00132    return (offset/ILBC_BUF_SIZE)*ILBC_SAMPLES;
00133 }
00134 
00135 static const struct ast_format ilbc_f = {
00136    .name = "iLBC",
00137    .exts = "ilbc",
00138    .format = AST_FORMAT_ILBC,
00139    .write = ilbc_write,
00140    .seek = ilbc_seek,
00141    .trunc = ilbc_trunc,
00142    .tell = ilbc_tell,
00143    .read = ilbc_read,
00144    .buf_size = ILBC_BUF_SIZE + AST_FRIENDLY_OFFSET,
00145 };
00146 
00147 static int load_module(void)
00148 {
00149    return ast_format_register(&ilbc_f);
00150 }
00151 
00152 static int unload_module(void)
00153 {
00154    return ast_format_unregister(ilbc_f.name);
00155 }  
00156 
00157 AST_MODULE_INFO(ASTERISK_GPL_KEY, AST_MODFLAG_LOAD_FIRST, "Raw iLBC data",
00158    .load = load_module,
00159    .unload = unload_module,
00160 );

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