Thu Apr 28 2011 17:15:22

Asterisk developer's documentation


format_siren7.c

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00001 /*
00002  * Asterisk -- An open source telephony toolkit.
00003  *
00004  * Copyright (C) 1999 - 2008, Anthony Minessale and Digium, Inc.
00005  * Anthony Minessale (anthmct@yahoo.com)
00006  * Kevin P. Fleming <kpfleming@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 ITU G.722.1 (Siren7, licensed from Polycom) format, 32kbps bitrate only
00022  * \arg File name extensions: siren7
00023  * \ingroup formats
00024  */
00025  
00026 #include "asterisk.h"
00027 
00028 ASTERISK_FILE_VERSION(__FILE__, "$Revision: 233694 $")
00029 
00030 #include "asterisk/mod_format.h"
00031 #include "asterisk/module.h"
00032 #include "asterisk/endian.h"
00033 
00034 #define BUF_SIZE  80    /* 20 milliseconds == 80 bytes, 320 samples */
00035 #define SAMPLES_TO_BYTES(x)   x / (320 / 80)
00036 #define BYTES_TO_SAMPLES(x)   x * (320 / 80)
00037 
00038 static struct ast_frame *siren7read(struct ast_filestream *s, int *whennext)
00039 {
00040    int res;
00041    /* Send a frame from the file to the appropriate channel */
00042 
00043    s->fr.frametype = AST_FRAME_VOICE;
00044    s->fr.subclass = AST_FORMAT_SIREN7;
00045    s->fr.mallocd = 0;
00046    AST_FRAME_SET_BUFFER(&s->fr, s->buf, AST_FRIENDLY_OFFSET, BUF_SIZE);
00047    if ((res = fread(s->fr.data.ptr, 1, s->fr.datalen, s->f)) != s->fr.datalen) {
00048       if (res)
00049          ast_log(LOG_WARNING, "Short read (%d) (%s)!\n", res, strerror(errno));
00050       return NULL;
00051    }
00052    *whennext = s->fr.samples = BYTES_TO_SAMPLES(res);
00053    return &s->fr;
00054 }
00055 
00056 static int siren7write(struct ast_filestream *fs, struct ast_frame *f)
00057 {
00058    int res;
00059 
00060    if (f->frametype != AST_FRAME_VOICE) {
00061       ast_log(LOG_WARNING, "Asked to write non-voice frame!\n");
00062       return -1;
00063    }
00064    if (f->subclass != AST_FORMAT_SIREN7) {
00065       ast_log(LOG_WARNING, "Asked to write non-Siren7 frame (%d)!\n", f->subclass);
00066       return -1;
00067    }
00068    if ((res = fwrite(f->data.ptr, 1, f->datalen, fs->f)) != f->datalen) {
00069       ast_log(LOG_WARNING, "Bad write (%d/%d): %s\n", res, f->datalen, strerror(errno));
00070       return -1;
00071    }
00072    return 0;
00073 }
00074 
00075 static int siren7seek(struct ast_filestream *fs, off_t sample_offset, int whence)
00076 {
00077    off_t offset = 0, min = 0, cur, max;
00078 
00079    sample_offset = SAMPLES_TO_BYTES(sample_offset);
00080 
00081    cur = ftello(fs->f);
00082 
00083    fseeko(fs->f, 0, SEEK_END);
00084 
00085    max = ftello(fs->f);
00086 
00087    if (whence == SEEK_SET)
00088       offset = sample_offset;
00089    else if (whence == SEEK_CUR || whence == SEEK_FORCECUR)
00090       offset = sample_offset + cur;
00091    else if (whence == SEEK_END)
00092       offset = max - sample_offset;
00093 
00094    if (whence != SEEK_FORCECUR)
00095       offset = (offset > max) ? max : offset;
00096 
00097    /* always protect against seeking past begining. */
00098    offset = (offset < min) ? min : offset;
00099 
00100    return fseeko(fs->f, offset, SEEK_SET);
00101 }
00102 
00103 static int siren7trunc(struct ast_filestream *fs)
00104 {
00105    return ftruncate(fileno(fs->f), ftello(fs->f));
00106 }
00107 
00108 static off_t siren7tell(struct ast_filestream *fs)
00109 {
00110    return BYTES_TO_SAMPLES(ftello(fs->f));
00111 }
00112 
00113 static const struct ast_format siren7_f = {
00114    .name = "siren7",
00115    .exts = "siren7",
00116    .format = AST_FORMAT_SIREN7,
00117    .write = siren7write,
00118    .seek = siren7seek,
00119    .trunc = siren7trunc,
00120    .tell = siren7tell,
00121    .read = siren7read,
00122    .buf_size = BUF_SIZE + AST_FRIENDLY_OFFSET,
00123 };
00124 
00125 static int load_module(void)
00126 {
00127    if (ast_format_register(&siren7_f))
00128       return AST_MODULE_LOAD_DECLINE;
00129 
00130    return AST_MODULE_LOAD_SUCCESS;
00131 }
00132 
00133 static int unload_module(void)
00134 {
00135    return ast_format_unregister(siren7_f.name);
00136 }  
00137 
00138 AST_MODULE_INFO(ASTERISK_GPL_KEY, AST_MODFLAG_LOAD_ORDER, "ITU G.722.1 (Siren7, licensed from Polycom)",
00139    .load = load_module,
00140    .unload = unload_module,
00141    .load_pri = 10,
00142 );