Sat Sep 16 07:28:08 2006

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 <unistd.h>
00030 #include <netinet/in.h>
00031 #include <arpa/inet.h>
00032 #include <stdlib.h>
00033 #include <sys/time.h>
00034 #include <stdio.h>
00035 #include <errno.h>
00036 #include <string.h>
00037 
00038 #include "asterisk.h"
00039 
00040 ASTERISK_FILE_VERSION(__FILE__, "$Revision: 7221 $")
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 struct ast_filestream {
00055    void *reserved[AST_RESERVED_POINTERS];
00056    /* Believe it or not, we must decode/recode to account for the
00057       weird MS format */
00058    /* This is what a filestream means to us */
00059    FILE *f; /* Descriptor */
00060    struct ast_frame fr;          /* Frame information */
00061    char waste[AST_FRIENDLY_OFFSET]; /* Buffer for sending frames, etc */
00062    char empty;                   /* Empty character */
00063    unsigned char g729[20];          /* Two Real G729 Frames */
00064 };
00065 
00066 
00067 AST_MUTEX_DEFINE_STATIC(g729_lock);
00068 static int glistcnt = 0;
00069 
00070 static char *name = "g729";
00071 static char *desc = "Raw G729 data";
00072 static char *exts = "g729";
00073 
00074 static struct ast_filestream *g729_open(FILE *f)
00075 {
00076    /* We don't have any header to read or anything really, but
00077       if we did, it would go here.  We also might want to check
00078       and be sure it's a valid file.  */
00079    struct ast_filestream *tmp;
00080    if ((tmp = malloc(sizeof(struct ast_filestream)))) {
00081       memset(tmp, 0, sizeof(struct ast_filestream));
00082       if (ast_mutex_lock(&g729_lock)) {
00083          ast_log(LOG_WARNING, "Unable to lock g729 list\n");
00084          free(tmp);
00085          return NULL;
00086       }
00087       tmp->f = f;
00088       tmp->fr.data = tmp->g729;
00089       tmp->fr.frametype = AST_FRAME_VOICE;
00090       tmp->fr.subclass = AST_FORMAT_G729A;
00091       /* datalen will vary for each frame */
00092       tmp->fr.src = name;
00093       tmp->fr.mallocd = 0;
00094       glistcnt++;
00095       ast_mutex_unlock(&g729_lock);
00096       ast_update_use_count();
00097    }
00098    return tmp;
00099 }
00100 
00101 static struct ast_filestream *g729_rewrite(FILE *f, const char *comment)
00102 {
00103    /* We don't have any header to read or anything really, but
00104       if we did, it would go here.  We also might want to check
00105       and be sure it's a valid file.  */
00106    struct ast_filestream *tmp;
00107    if ((tmp = malloc(sizeof(struct ast_filestream)))) {
00108       memset(tmp, 0, sizeof(struct ast_filestream));
00109       if (ast_mutex_lock(&g729_lock)) {
00110          ast_log(LOG_WARNING, "Unable to lock g729 list\n");
00111          free(tmp);
00112          return NULL;
00113       }
00114       tmp->f = f;
00115       glistcnt++;
00116       ast_mutex_unlock(&g729_lock);
00117       ast_update_use_count();
00118    } else
00119       ast_log(LOG_WARNING, "Out of memory\n");
00120    return tmp;
00121 }
00122 
00123 static void g729_close(struct ast_filestream *s)
00124 {
00125    if (ast_mutex_lock(&g729_lock)) {
00126       ast_log(LOG_WARNING, "Unable to lock g729 list\n");
00127       return;
00128    }
00129    glistcnt--;
00130    ast_mutex_unlock(&g729_lock);
00131    ast_update_use_count();
00132    fclose(s->f);
00133    free(s);
00134    s = NULL;
00135 }
00136 
00137 static struct ast_frame *g729_read(struct ast_filestream *s, int *whennext)
00138 {
00139    int res;
00140    /* Send a frame from the file to the appropriate channel */
00141    s->fr.frametype = AST_FRAME_VOICE;
00142    s->fr.subclass = AST_FORMAT_G729A;
00143    s->fr.offset = AST_FRIENDLY_OFFSET;
00144    s->fr.samples = 160;
00145    s->fr.datalen = 20;
00146    s->fr.mallocd = 0;
00147    s->fr.data = s->g729;
00148    if ((res = fread(s->g729, 1, 20, s->f)) != 20) {
00149       if (res && (res != 10))
00150          ast_log(LOG_WARNING, "Short read (%d) (%s)!\n", res, strerror(errno));
00151       return NULL;
00152    }
00153    *whennext = s->fr.samples;
00154    return &s->fr;
00155 }
00156 
00157 static int g729_write(struct ast_filestream *fs, struct ast_frame *f)
00158 {
00159    int res;
00160    if (f->frametype != AST_FRAME_VOICE) {
00161       ast_log(LOG_WARNING, "Asked to write non-voice frame!\n");
00162       return -1;
00163    }
00164    if (f->subclass != AST_FORMAT_G729A) {
00165       ast_log(LOG_WARNING, "Asked to write non-G729 frame (%d)!\n", f->subclass);
00166       return -1;
00167    }
00168    if (f->datalen % 10) {
00169       ast_log(LOG_WARNING, "Invalid data length, %d, should be multiple of 10\n", f->datalen);
00170       return -1;
00171    }
00172    if ((res = fwrite(f->data, 1, f->datalen, fs->f)) != f->datalen) {
00173          ast_log(LOG_WARNING, "Bad write (%d/10): %s\n", res, strerror(errno));
00174          return -1;
00175    }
00176    return 0;
00177 }
00178 
00179 static char *g729_getcomment(struct ast_filestream *s)
00180 {
00181    return NULL;
00182 }
00183 
00184 static int g729_seek(struct ast_filestream *fs, long sample_offset, int whence)
00185 {
00186    long bytes;
00187    off_t min,cur,max,offset=0;
00188    min = 0;
00189    cur = ftell(fs->f);
00190    fseek(fs->f, 0, SEEK_END);
00191    max = ftell(fs->f);
00192    
00193    bytes = 20 * (sample_offset / 160);
00194    if (whence == SEEK_SET)
00195       offset = bytes;
00196    else if (whence == SEEK_CUR || whence == SEEK_FORCECUR)
00197       offset = cur + bytes;
00198    else if (whence == SEEK_END)
00199       offset = max - bytes;
00200    if (whence != SEEK_FORCECUR) {
00201       offset = (offset > max)?max:offset;
00202    }
00203    /* protect against seeking beyond begining. */
00204    offset = (offset < min)?min:offset;
00205    if (fseek(fs->f, offset, SEEK_SET) < 0)
00206       return -1;
00207    return 0;
00208 }
00209 
00210 static int g729_trunc(struct ast_filestream *fs)
00211 {
00212    /* Truncate file to current length */
00213    if (ftruncate(fileno(fs->f), ftell(fs->f)) < 0)
00214       return -1;
00215    return 0;
00216 }
00217 
00218 static long g729_tell(struct ast_filestream *fs)
00219 {
00220    off_t offset;
00221    offset = ftell(fs->f);
00222    return (offset/20)*160;
00223 }
00224 
00225 int load_module()
00226 {
00227    return ast_format_register(name, exts, AST_FORMAT_G729A,
00228                         g729_open,
00229                         g729_rewrite,
00230                         g729_write,
00231                         g729_seek,
00232                         g729_trunc,
00233                         g729_tell,
00234                         g729_read,
00235                         g729_close,
00236                         g729_getcomment);
00237                         
00238                         
00239 }
00240 
00241 int unload_module()
00242 {
00243    return ast_format_unregister(name);
00244 }  
00245 
00246 int usecount()
00247 {
00248    return glistcnt;
00249 }
00250 
00251 char *description()
00252 {
00253    return desc;
00254 }
00255 
00256 
00257 char *key()
00258 {
00259    return ASTERISK_GPL_KEY;
00260 }

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