Asterisk.org: Developer Documentation (28 Oct 2009)

Wed Oct 28 15:47:53 2009

## Asterisk developer's documentation

# format_g723.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 /*!
    00020  * \file
    00021  *
    00022  * \brief Old-style G.723.1 frame/timestamp format.
    00023  *
    00024  * \arg Extensions: g723, g723sf
    00025  * \ingroup formats
    00026  */
    00027
    00028 #include <unistd.h>
    00029 #include <netinet/in.h>
    00030 #include <arpa/inet.h>
    00031 #include <stdlib.h>
    00032 #include <stdio.h>
    00033 #include <errno.h>
    00034 #include <string.h>
    00035 #include <sys/time.h>
    00036
    00037 #include "asterisk.h"
    00038
    00039 ASTERISK_FILE_VERSION(__FILE__, "$Revision: 7221 $")
    00040
    00041 #include "asterisk/lock.h"
    00042 #include "asterisk/channel.h"
    00043 #include "asterisk/file.h"
    00044 #include "asterisk/logger.h"
    00045 #include "asterisk/sched.h"
    00046 #include "asterisk/module.h"
    00047
    00048 #include "../channels/adtranvofr.h"
    00049
    00050
    00051 #define G723_MAX_SIZE 1024
    00052
    00053 struct ast_filestream {
    00054    /* First entry MUST be reserved for the channel type */
    00055    void *reserved[AST_RESERVED_POINTERS];
    00056    /* This is what a filestream means to us */
    00057    FILE *f; /* Descriptor */
    00058    struct ast_filestream *next;
    00059    struct ast_frame *fr;   /* Frame representation of buf */
    00060    struct timeval orig; /* Original frame time */
    00061    char buf[G723_MAX_SIZE + AST_FRIENDLY_OFFSET];  /* Buffer for sending frames, etc */
    00062 };
    00063
    00064
    00065 AST_MUTEX_DEFINE_STATIC(g723_lock);
    00066 static int glistcnt = 0;
    00067
    00068 static char *name = "g723sf";
    00069 static char *desc = "G.723.1 Simple Timestamp File Format";
    00070 static char *exts = "g723|g723sf";
    00071
    00072 static struct ast_filestream *g723_open(FILE *f)
    00073 {
    00074    /* We don't have any header to read or anything really, but
    00075       if we did, it would go here.  We also might want to check
    00076       and be sure it's a valid file.  */
    00077    struct ast_filestream *tmp;
    00078    if ((tmp = malloc(sizeof(struct ast_filestream)))) {
    00079       memset(tmp, 0, sizeof(struct ast_filestream));
    00080       if (ast_mutex_lock(&g723_lock)) {
    00081          ast_log(LOG_WARNING, "Unable to lock g723 list\n");
    00082          free(tmp);
    00083          return NULL;
    00084       }
    00085       tmp->f = f;
    00086       tmp->fr = (struct ast_frame *)tmp->buf;
    00087       tmp->fr->data = tmp->buf + sizeof(struct ast_frame);
    00088       tmp->fr->frametype = AST_FRAME_VOICE;
    00089       tmp->fr->subclass = AST_FORMAT_G723_1;
    00090       /* datalen will vary for each frame */
    00091       tmp->fr->src = name;
    00092       tmp->fr->mallocd = 0;
    00093       glistcnt++;
    00094       ast_mutex_unlock(&g723_lock);
    00095       ast_update_use_count();
    00096    }
    00097    return tmp;
    00098 }
    00099
    00100 static struct ast_filestream *g723_rewrite(FILE *f, const char *comment)
    00101 {
    00102    /* We don't have any header to read or anything really, but
    00103       if we did, it would go here.  We also might want to check
    00104       and be sure it's a valid file.  */
    00105    struct ast_filestream *tmp;
    00106    if ((tmp = malloc(sizeof(struct ast_filestream)))) {
    00107       memset(tmp, 0, sizeof(struct ast_filestream));
    00108       if (ast_mutex_lock(&g723_lock)) {
    00109          ast_log(LOG_WARNING, "Unable to lock g723 list\n");
    00110          free(tmp);
    00111          return NULL;
    00112       }
    00113       tmp->f = f;
    00114       glistcnt++;
    00115       ast_mutex_unlock(&g723_lock);
    00116       ast_update_use_count();
    00117    } else
    00118       ast_log(LOG_WARNING, "Out of memory\n");
    00119    return tmp;
    00120 }
    00121
    00122 static struct ast_frame *g723_read(struct ast_filestream *s, int *whennext)
    00123 {
    00124    unsigned short size;
    00125    int res;
    00126    int delay;
    00127    /* Read the delay for the next packet, and schedule again if necessary */
    00128    if (fread(&delay, 1, 4, s->f) == 4)
    00129       delay = ntohl(delay);
    00130    else
    00131       delay = -1;
    00132    if (fread(&size, 1, 2, s->f) != 2) {
    00133       /* Out of data, or the file is no longer valid.  In any case
    00134          go ahead and stop the stream */
    00135       return NULL;
    00136    }
    00137    /* Looks like we have a frame to read from here */
    00138    size = ntohs(size);
    00139    if (size > G723_MAX_SIZE - sizeof(struct ast_frame)) {
    00140       ast_log(LOG_WARNING, "Size %d is invalid\n", size);
    00141       /* The file is apparently no longer any good, as we
    00142          shouldn't ever get frames even close to this
    00143          size.  */
    00144       return NULL;
    00145    }
    00146    /* Read the data into the buffer */
    00147    s->fr->offset = AST_FRIENDLY_OFFSET;
    00148    s->fr->datalen = size;
    00149    s->fr->data = s->buf + sizeof(struct ast_frame) + AST_FRIENDLY_OFFSET;
    00150    if ((res = fread(s->fr->data, 1, size, s->f)) != size) {
    00151       ast_log(LOG_WARNING, "Short read (%d of %d bytes) (%s)!\n", res, size, strerror(errno));
    00152       return NULL;
    00153    }
    00154 #if 0
    00155       /* Average out frames <= 50 ms */
    00156       if (delay < 50)
    00157          s->fr->timelen = 30;
    00158       else
    00159          s->fr->timelen = delay;
    00160 #else
    00161       s->fr->samples = 240;
    00162 #endif
    00163    *whennext = s->fr->samples;
    00164    return s->fr;
    00165 }
    00166
    00167 static void g723_close(struct ast_filestream *s)
    00168 {
    00169    if (ast_mutex_lock(&g723_lock)) {
    00170       ast_log(LOG_WARNING, "Unable to lock g723 list\n");
    00171       return;
    00172    }
    00173    glistcnt--;
    00174    ast_mutex_unlock(&g723_lock);
    00175    ast_update_use_count();
    00176    fclose(s->f);
    00177    free(s);
    00178    s = NULL;
    00179 }
    00180
    00181
    00182 static int g723_write(struct ast_filestream *fs, struct ast_frame *f)
    00183 {
    00184    u_int32_t delay;
    00185    u_int16_t size;
    00186    int res;
    00187    if (fs->fr) {
    00188       ast_log(LOG_WARNING, "Asked to write on a read stream??\n");
    00189       return -1;
    00190    }
    00191    if (f->frametype != AST_FRAME_VOICE) {
    00192       ast_log(LOG_WARNING, "Asked to write non-voice frame!\n");
    00193       return -1;
    00194    }
    00195    if (f->subclass != AST_FORMAT_G723_1) {
    00196       ast_log(LOG_WARNING, "Asked to write non-g723 frame!\n");
    00197       return -1;
    00198    }
    00199    delay = 0;
    00200    if (f->datalen <= 0) {
    00201       ast_log(LOG_WARNING, "Short frame ignored (%d bytes long?)\n", f->datalen);
    00202       return 0;
    00203    }
    00204    if ((res = fwrite(&delay, 1, 4, fs->f)) != 4) {
    00205       ast_log(LOG_WARNING, "Unable to write delay: res=%d (%s)\n", res, strerror(errno));
    00206       return -1;
    00207    }
    00208    size = htons(f->datalen);
    00209    if ((res = fwrite(&size, 1, 2, fs->f)) != 2) {
    00210       ast_log(LOG_WARNING, "Unable to write size: res=%d (%s)\n", res, strerror(errno));
    00211       return -1;
    00212    }
    00213    if ((res = fwrite(f->data, 1, f->datalen, fs->f)) != f->datalen) {
    00214       ast_log(LOG_WARNING, "Unable to write frame: res=%d (%s)\n", res, strerror(errno));
    00215       return -1;
    00216    }
    00217    return 0;
    00218 }
    00219
    00220 static int g723_seek(struct ast_filestream *fs, long sample_offset, int whence)
    00221 {
    00222    return -1;
    00223 }
    00224
    00225 static int g723_trunc(struct ast_filestream *fs)
    00226 {
    00227    /* Truncate file to current length */
    00228    if (ftruncate(fileno(fs->f), ftell(fs->f)) < 0)
    00229       return -1;
    00230    return 0;
    00231 }
    00232
    00233 static long g723_tell(struct ast_filestream *fs)
    00234 {
    00235    return -1;
    00236 }
    00237
    00238 static char *g723_getcomment(struct ast_filestream *s)
    00239 {
    00240    return NULL;
    00241 }
    00242
    00243 int load_module()
    00244 {
    00245    return ast_format_register(name, exts, AST_FORMAT_G723_1,
    00246                         g723_open,
    00247                         g723_rewrite,
    00248                         g723_write,
    00249                         g723_seek,
    00250                         g723_trunc,
    00251                         g723_tell,
    00252                         g723_read,
    00253                         g723_close,
    00254                         g723_getcomment);
    00255
    00256
    00257 }
    00258
    00259 int unload_module()
    00260 {
    00261    return ast_format_unregister(name);
    00262 }
    00263
    00264 int usecount()
    00265 {
    00266    return glistcnt;
    00267 }
    00268
    00269 char *description()
    00270 {
    00271    return desc;
    00272 }
    00273
    00274
    00275 char *key()
    00276 {
    00277    return ASTERISK_GPL_KEY;
    00278 }