Wed Jan 27 20:02:11 2016

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 /*** MODULEINFO
00029    <support_level>core</support_level>
00030  ***/
00031 
00032 #include "asterisk.h"
00033 
00034 ASTERISK_FILE_VERSION(__FILE__, "$Revision: 364578 $")
00035 
00036 #include "asterisk/mod_format.h"
00037 #include "asterisk/module.h"
00038 #include "asterisk/endian.h"
00039 
00040 /* Some Ideas for this code came from makeg729e.c by Jeffrey Chilton */
00041 
00042 /* Portions of the conversion code are by guido@sienanet.it */
00043 
00044 #define  ILBC_BUF_SIZE  50 /* One Real iLBC Frame */
00045 #define  ILBC_SAMPLES   240
00046 
00047 static struct ast_frame *ilbc_read(struct ast_filestream *s, int *whennext)
00048 {
00049    int res;
00050    /* Send a frame from the file to the appropriate channel */
00051    s->fr.frametype = AST_FRAME_VOICE;
00052    s->fr.subclass.codec = AST_FORMAT_ILBC;
00053    s->fr.mallocd = 0;
00054    AST_FRAME_SET_BUFFER(&s->fr, s->buf, AST_FRIENDLY_OFFSET, ILBC_BUF_SIZE);
00055    if ((res = fread(s->fr.data.ptr, 1, s->fr.datalen, s->f)) != s->fr.datalen) {
00056       if (res)
00057          ast_log(LOG_WARNING, "Short read (%d) (%s)!\n", res, strerror(errno));
00058       return NULL;
00059    }
00060    *whennext = s->fr.samples = ILBC_SAMPLES;
00061    return &s->fr;
00062 }
00063 
00064 static int ilbc_write(struct ast_filestream *fs, struct ast_frame *f)
00065 {
00066    int res;
00067    if (f->frametype != AST_FRAME_VOICE) {
00068       ast_log(LOG_WARNING, "Asked to write non-voice frame!\n");
00069       return -1;
00070    }
00071    if (f->subclass.codec != AST_FORMAT_ILBC) {
00072       ast_log(LOG_WARNING, "Asked to write non-iLBC frame (%s)!\n", ast_getformatname(f->subclass.codec));
00073       return -1;
00074    }
00075    if (f->datalen % 50) {
00076       ast_log(LOG_WARNING, "Invalid data length, %d, should be multiple of 50\n", f->datalen);
00077       return -1;
00078    }
00079    if ((res = fwrite(f->data.ptr, 1, f->datalen, fs->f)) != f->datalen) {
00080          ast_log(LOG_WARNING, "Bad write (%d/50): %s\n", res, strerror(errno));
00081          return -1;
00082    }
00083    return 0;
00084 }
00085 
00086 static int ilbc_seek(struct ast_filestream *fs, off_t sample_offset, int whence)
00087 {
00088    long bytes;
00089    off_t min,cur,max,offset=0;
00090    min = 0;
00091    cur = ftello(fs->f);
00092    fseeko(fs->f, 0, SEEK_END);
00093    max = ftello(fs->f);
00094    
00095    bytes = ILBC_BUF_SIZE * (sample_offset / ILBC_SAMPLES);
00096    if (whence == SEEK_SET)
00097       offset = bytes;
00098    else if (whence == SEEK_CUR || whence == SEEK_FORCECUR)
00099       offset = cur + bytes;
00100    else if (whence == SEEK_END)
00101       offset = max - bytes;
00102    if (whence != SEEK_FORCECUR) {
00103       offset = (offset > max)?max:offset;
00104    }
00105    /* protect against seeking beyond begining. */
00106    offset = (offset < min)?min:offset;
00107    if (fseeko(fs->f, offset, SEEK_SET) < 0)
00108       return -1;
00109    return 0;
00110 }
00111 
00112 static int ilbc_trunc(struct ast_filestream *fs)
00113 {
00114    int fd;
00115    off_t cur;
00116 
00117    if ((fd = fileno(fs->f)) < 0) {
00118       ast_log(AST_LOG_WARNING, "Unable to determine file descriptor for iLBC filestream %p: %s\n", fs, strerror(errno));
00119       return -1;
00120    }
00121    if ((cur = ftello(fs->f)) < 0) {
00122       ast_log(AST_LOG_WARNING, "Unable to determine current position in iLBC filestream %p: %s\n", fs, strerror(errno));
00123       return -1;
00124    }
00125    /* Truncate file to current length */
00126    return ftruncate(fd, cur);
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    if (ast_format_register(&ilbc_f))
00150       return AST_MODULE_LOAD_FAILURE;
00151    return AST_MODULE_LOAD_SUCCESS;
00152 }
00153 
00154 static int unload_module(void)
00155 {
00156    return ast_format_unregister(ilbc_f.name);
00157 }
00158 
00159 AST_MODULE_INFO(ASTERISK_GPL_KEY, AST_MODFLAG_LOAD_ORDER, "Raw iLBC data",
00160    .load = load_module,
00161    .unload = unload_module,
00162    .load_pri = AST_MODPRI_APP_DEPEND
00163 );

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