Sat Aug 6 00:39:20 2011

Asterisk developer's documentation


app_echo.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 Echo application -- play back what you hear to evaluate latency
00022  *
00023  * \author Mark Spencer <markster@digium.com>
00024  * 
00025  * \ingroup applications
00026  */
00027 
00028 #include "asterisk.h"
00029 
00030 ASTERISK_FILE_VERSION(__FILE__, "$Revision: 249946 $")
00031 
00032 #include <stdlib.h>
00033 #include <stdio.h>
00034 #include <unistd.h>
00035 #include <string.h>
00036 
00037 #include "asterisk/lock.h"
00038 #include "asterisk/file.h"
00039 #include "asterisk/logger.h"
00040 #include "asterisk/channel.h"
00041 #include "asterisk/pbx.h"
00042 #include "asterisk/module.h"
00043 
00044 static char *app = "Echo";
00045 
00046 static char *synopsis = "Echo audio, video, or DTMF back to the calling party";
00047 
00048 static char *descrip = 
00049 "  Echo(): This application will echo any audio, video, or DTMF frames read from\n"
00050 "the calling channel back to itself. If the DTMF digit '#' is received, the\n"
00051 "application will exit.\n";
00052 
00053 
00054 static int echo_exec(struct ast_channel *chan, void *data)
00055 {
00056    int res = -1;
00057    int format;
00058    struct ast_module_user *u;
00059 
00060    u = ast_module_user_add(chan);
00061 
00062    format = ast_best_codec(chan->nativeformats);
00063    ast_set_write_format(chan, format);
00064    ast_set_read_format(chan, format);
00065 
00066    while (ast_waitfor(chan, -1) > -1) {
00067       struct ast_frame *f = ast_read(chan);
00068       if (!f) {
00069          break;
00070       }
00071       f->delivery.tv_sec = 0;
00072       f->delivery.tv_usec = 0;
00073       if (ast_write(chan, f)) {
00074          ast_frfree(f);
00075          goto end;
00076       }
00077       if ((f->frametype == AST_FRAME_DTMF) && (f->subclass == '#')) {
00078          res = 0;
00079          ast_frfree(f);
00080          goto end;
00081       }
00082       ast_frfree(f);
00083    }
00084 end:
00085    ast_module_user_remove(u);
00086    return res;
00087 }
00088 
00089 static int unload_module(void)
00090 {
00091    int res;
00092 
00093    res = ast_unregister_application(app);
00094 
00095    ast_module_user_hangup_all();
00096 
00097    return res;
00098 }
00099 
00100 static int load_module(void)
00101 {
00102    return ast_register_application(app, echo_exec, synopsis, descrip);
00103 }
00104 
00105 AST_MODULE_INFO_STANDARD(ASTERISK_GPL_KEY, "Simple Echo Application");

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