Sat Sep 16 07:28:08 2006

Asterisk developer's documentation


format_h263.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 h263 data.
00022  * \arg File name extension: h263
00023  * \ingroup formats
00024  */
00025  
00026 #include <unistd.h>
00027 #include <netinet/in.h>
00028 #include <arpa/inet.h>
00029 #include <stdlib.h>
00030 #include <sys/time.h>
00031 #include <stdio.h>
00032 #include <errno.h>
00033 #include <string.h>
00034 
00035 #include "asterisk.h"
00036 
00037 ASTERISK_FILE_VERSION(__FILE__, "$Revision: 37808 $")
00038 
00039 #include "asterisk/lock.h"
00040 #include "asterisk/channel.h"
00041 #include "asterisk/file.h"
00042 #include "asterisk/logger.h"
00043 #include "asterisk/sched.h"
00044 #include "asterisk/module.h"
00045 #include "asterisk/endian.h"
00046 
00047 /* Some Ideas for this code came from makeh263e.c by Jeffrey Chilton */
00048 
00049 /* Portions of the conversion code are by guido@sienanet.it */
00050 
00051 struct ast_filestream {
00052    void *reserved[AST_RESERVED_POINTERS];
00053    /* Believe it or not, we must decode/recode to account for the
00054       weird MS format */
00055    /* This is what a filestream means to us */
00056    FILE *f; /* Descriptor */
00057    unsigned int lastts;
00058    struct ast_frame fr;          /* Frame information */
00059    char waste[AST_FRIENDLY_OFFSET]; /* Buffer for sending frames, etc */
00060    char empty;                   /* Empty character */
00061    unsigned char h263[32768];          /* Four real h263 Frames */
00062 };
00063 
00064 
00065 AST_MUTEX_DEFINE_STATIC(h263_lock);
00066 static int glistcnt = 0;
00067 
00068 static char *name = "h263";
00069 static char *desc = "Raw h263 data";
00070 static char *exts = "h263";
00071 
00072 static struct ast_filestream *h263_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    unsigned int ts;
00079    int res;
00080    if ((res = fread(&ts, 1, sizeof(ts), f)) < sizeof(ts)) {
00081       ast_log(LOG_WARNING, "Empty file!\n");
00082       return NULL;
00083    }
00084       
00085    if ((tmp = malloc(sizeof(struct ast_filestream)))) {
00086       memset(tmp, 0, sizeof(struct ast_filestream));
00087       if (ast_mutex_lock(&h263_lock)) {
00088          ast_log(LOG_WARNING, "Unable to lock h263 list\n");
00089          free(tmp);
00090          return NULL;
00091       }
00092       tmp->f = f;
00093       tmp->fr.data = tmp->h263;
00094       tmp->fr.frametype = AST_FRAME_VIDEO;
00095       tmp->fr.subclass = AST_FORMAT_H263;
00096       /* datalen will vary for each frame */
00097       tmp->fr.src = name;
00098       tmp->fr.mallocd = 0;
00099       glistcnt++;
00100       ast_mutex_unlock(&h263_lock);
00101       ast_update_use_count();
00102    }
00103    return tmp;
00104 }
00105 
00106 static struct ast_filestream *h263_rewrite(FILE *f, const char *comment)
00107 {
00108    /* We don't have any header to read or anything really, but
00109       if we did, it would go here.  We also might want to check
00110       and be sure it's a valid file.  */
00111    struct ast_filestream *tmp;
00112    if ((tmp = malloc(sizeof(struct ast_filestream)))) {
00113       memset(tmp, 0, sizeof(struct ast_filestream));
00114       if (ast_mutex_lock(&h263_lock)) {
00115          ast_log(LOG_WARNING, "Unable to lock h263 list\n");
00116          free(tmp);
00117          return NULL;
00118       }
00119       tmp->f = f;
00120       glistcnt++;
00121       ast_mutex_unlock(&h263_lock);
00122       ast_update_use_count();
00123    } else
00124       ast_log(LOG_WARNING, "Out of memory\n");
00125    return tmp;
00126 }
00127 
00128 static void h263_close(struct ast_filestream *s)
00129 {
00130    if (ast_mutex_lock(&h263_lock)) {
00131       ast_log(LOG_WARNING, "Unable to lock h263 list\n");
00132       return;
00133    }
00134    glistcnt--;
00135    ast_mutex_unlock(&h263_lock);
00136    ast_update_use_count();
00137    fclose(s->f);
00138    free(s);
00139    s = NULL;
00140 }
00141 
00142 static struct ast_frame *h263_read(struct ast_filestream *s, int *whennext)
00143 {
00144    int res;
00145    int mark=0;
00146    unsigned short len;
00147    unsigned int ts;
00148    /* Send a frame from the file to the appropriate channel */
00149    s->fr.frametype = AST_FRAME_VIDEO;
00150    s->fr.subclass = AST_FORMAT_H263;
00151    s->fr.offset = AST_FRIENDLY_OFFSET;
00152    s->fr.mallocd = 0;
00153    s->fr.data = s->h263;
00154    if ((res = fread(&len, 1, sizeof(len), s->f)) < 1) {
00155       return NULL;
00156    }
00157    len = ntohs(len);
00158    if (len & 0x8000) {
00159       mark = 1;
00160    }
00161    len &= 0x7fff;
00162    if (len > sizeof(s->h263)) {
00163       ast_log(LOG_WARNING, "Length %d is too long\n", len);
00164       return NULL;
00165    }
00166    if ((res = fread(s->h263, 1, len, s->f)) != len) {
00167       if (res)
00168          ast_log(LOG_WARNING, "Short read (%d) (%s)!\n", res, strerror(errno));
00169       return NULL;
00170    }
00171    s->fr.samples = s->lastts;
00172    s->fr.datalen = len;
00173    s->fr.subclass |= mark;
00174    s->fr.delivery.tv_sec = 0;
00175    s->fr.delivery.tv_usec = 0;
00176    if ((res = fread(&ts, 1, sizeof(ts), s->f)) == sizeof(ts)) {
00177       s->lastts = ntohl(ts);
00178       *whennext = s->lastts * 4/45;
00179    } else
00180       *whennext = 0;
00181    return &s->fr;
00182 }
00183 
00184 static int h263_write(struct ast_filestream *fs, struct ast_frame *f)
00185 {
00186    int res;
00187    unsigned int ts;
00188    unsigned short len;
00189    int subclass;
00190    int mark=0;
00191    if (f->frametype != AST_FRAME_VIDEO) {
00192       ast_log(LOG_WARNING, "Asked to write non-video frame!\n");
00193       return -1;
00194    }
00195    subclass = f->subclass;
00196    if (subclass & 0x1)
00197       mark=0x8000;
00198    subclass &= ~0x1;
00199    if (subclass != AST_FORMAT_H263) {
00200       ast_log(LOG_WARNING, "Asked to write non-h263 frame (%d)!\n", f->subclass);
00201       return -1;
00202    }
00203    ts = htonl(f->samples);
00204    if ((res = fwrite(&ts, 1, sizeof(ts), fs->f)) != sizeof(ts)) {
00205          ast_log(LOG_WARNING, "Bad write (%d/4): %s\n", res, strerror(errno));
00206          return -1;
00207    }
00208    len = htons(f->datalen | mark);
00209    if ((res = fwrite(&len, 1, sizeof(len), fs->f)) != sizeof(len)) {
00210          ast_log(LOG_WARNING, "Bad write (%d/2): %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, "Bad write (%d/%d): %s\n", res, f->datalen, strerror(errno));
00215          return -1;
00216    }
00217    return 0;
00218 }
00219 
00220 static char *h263_getcomment(struct ast_filestream *s)
00221 {
00222    return NULL;
00223 }
00224 
00225 static int h263_seek(struct ast_filestream *fs, long sample_offset, int whence)
00226 {
00227    /* No way Jose */
00228    return -1;
00229 }
00230 
00231 static int h263_trunc(struct ast_filestream *fs)
00232 {
00233    /* Truncate file to current length */
00234    if (ftruncate(fileno(fs->f), ftell(fs->f)) < 0)
00235       return -1;
00236    return 0;
00237 }
00238 
00239 static long h263_tell(struct ast_filestream *fs)
00240 {
00241    /* XXX This is totally bogus XXX */
00242    off_t offset;
00243    offset = ftell(fs->f);
00244    return (offset/20)*160;
00245 }
00246 
00247 int load_module()
00248 {
00249    return ast_format_register(name, exts, AST_FORMAT_H263,
00250                         h263_open,
00251                         h263_rewrite,
00252                         h263_write,
00253                         h263_seek,
00254                         h263_trunc,
00255                         h263_tell,
00256                         h263_read,
00257                         h263_close,
00258                         h263_getcomment);
00259                         
00260                         
00261 }
00262 
00263 int unload_module()
00264 {
00265    return ast_format_unregister(name);
00266 }  
00267 
00268 int usecount()
00269 {
00270    return glistcnt;
00271 }
00272 
00273 char *description()
00274 {
00275    return desc;
00276 }
00277 
00278 
00279 char *key()
00280 {
00281    return ASTERISK_GPL_KEY;
00282 }

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