Sat Aug 6 00:39:28 2011

Asterisk developer's documentation


format_g729.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 Save to raw, headerless G729 data.
00022  * \note This is not an encoder/decoder. The codec fo g729 is only
00023  * available with a commercial license from Digium, due to patent
00024  * restrictions. Check http://www.digium.com for information.
00025  * \arg Extensions: g729 
00026  * \ingroup formats
00027  */
00028  
00029 #include "asterisk.h"
00030 
00031 ASTERISK_FILE_VERSION(__FILE__, "$Revision: 233782 $")
00032 
00033 #include <unistd.h>
00034 #include <netinet/in.h>
00035 #include <arpa/inet.h>
00036 #include <stdlib.h>
00037 #include <sys/time.h>
00038 #include <stdio.h>
00039 #include <errno.h>
00040 #include <string.h>
00041 
00042 #include "asterisk/lock.h"
00043 #include "asterisk/channel.h"
00044 #include "asterisk/file.h"
00045 #include "asterisk/logger.h"
00046 #include "asterisk/sched.h"
00047 #include "asterisk/module.h"
00048 #include "asterisk/endian.h"
00049 
00050 /* Some Ideas for this code came from makeg729e.c by Jeffrey Chilton */
00051 
00052 /* Portions of the conversion code are by guido@sienanet.it */
00053 
00054 #define  BUF_SIZE 20 /* two G729 frames */
00055 #define  G729A_SAMPLES  160
00056 
00057 static struct ast_frame *g729_read(struct ast_filestream *s, int *whennext)
00058 {
00059    int res;
00060    /* Send a frame from the file to the appropriate channel */
00061    s->fr.frametype = AST_FRAME_VOICE;
00062    s->fr.subclass = AST_FORMAT_G729A;
00063    s->fr.mallocd = 0;
00064    s->fr.samples = G729A_SAMPLES;
00065    AST_FRAME_SET_BUFFER(&s->fr, s->buf, AST_FRIENDLY_OFFSET, BUF_SIZE);
00066    if ((res = fread(s->fr.data, 1, s->fr.datalen, s->f)) != s->fr.datalen) {
00067       if (res && (res != 10)) /* XXX what for ? */
00068          ast_log(LOG_WARNING, "Short read (%d) (%s)!\n", res, strerror(errno));
00069       return NULL;
00070    }
00071    *whennext = s->fr.samples;
00072    return &s->fr;
00073 }
00074 
00075 static int g729_write(struct ast_filestream *fs, struct ast_frame *f)
00076 {
00077    int res;
00078    if (f->frametype != AST_FRAME_VOICE) {
00079       ast_log(LOG_WARNING, "Asked to write non-voice frame!\n");
00080       return -1;
00081    }
00082    if (f->subclass != AST_FORMAT_G729A) {
00083       ast_log(LOG_WARNING, "Asked to write non-G729 frame (%d)!\n", f->subclass);
00084       return -1;
00085    }
00086    if (f->datalen % 10) {
00087       ast_log(LOG_WARNING, "Invalid data length, %d, should be multiple of 10\n", f->datalen);
00088       return -1;
00089    }
00090    if ((res = fwrite(f->data, 1, f->datalen, fs->f)) != f->datalen) {
00091          ast_log(LOG_WARNING, "Bad write (%d/10): %s\n", res, strerror(errno));
00092          return -1;
00093    }
00094    return 0;
00095 }
00096 
00097 static int g729_seek(struct ast_filestream *fs, off_t sample_offset, int whence)
00098 {
00099    long bytes;
00100    off_t min,cur,max,offset=0;
00101    min = 0;
00102    cur = ftello(fs->f);
00103    fseeko(fs->f, 0, SEEK_END);
00104    max = ftello(fs->f);
00105    
00106    bytes = BUF_SIZE * (sample_offset / G729A_SAMPLES);
00107    if (whence == SEEK_SET)
00108       offset = bytes;
00109    else if (whence == SEEK_CUR || whence == SEEK_FORCECUR)
00110       offset = cur + bytes;
00111    else if (whence == SEEK_END)
00112       offset = max - bytes;
00113    if (whence != SEEK_FORCECUR) {
00114       offset = (offset > max)?max:offset;
00115    }
00116    /* protect against seeking beyond begining. */
00117    offset = (offset < min)?min:offset;
00118    if (fseeko(fs->f, offset, SEEK_SET) < 0)
00119       return -1;
00120    return 0;
00121 }
00122 
00123 static int g729_trunc(struct ast_filestream *fs)
00124 {
00125    /* Truncate file to current length */
00126    if (ftruncate(fileno(fs->f), ftello(fs->f)) < 0)
00127       return -1;
00128    return 0;
00129 }
00130 
00131 static off_t g729_tell(struct ast_filestream *fs)
00132 {
00133    off_t offset = ftello(fs->f);
00134    return (offset/BUF_SIZE)*G729A_SAMPLES;
00135 }
00136 
00137 static const struct ast_format g729_f = {
00138    .name = "g729",
00139    .exts = "g729",
00140    .format = AST_FORMAT_G729A,
00141    .write = g729_write,
00142    .seek = g729_seek,
00143    .trunc = g729_trunc,
00144    .tell = g729_tell,
00145    .read = g729_read,
00146    .buf_size = BUF_SIZE + AST_FRIENDLY_OFFSET,
00147 };
00148 
00149 static int load_module(void)
00150 {
00151    return ast_format_register(&g729_f);
00152 }
00153 
00154 static int unload_module(void)
00155 {
00156    return ast_format_unregister(g729_f.name);
00157 }  
00158 
00159 AST_MODULE_INFO(ASTERISK_GPL_KEY, AST_MODFLAG_LOAD_FIRST, "Raw G729 data",
00160    .load = load_module,
00161    .unload = unload_module,
00162 );

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