Sat Aug 6 00:39:28 2011

Asterisk developer's documentation


format_h264.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 h264 data.
00022  * \arg File name extension: h264
00023  * \ingroup formats
00024  * \arg See \ref AstVideo
00025  */
00026  
00027 #include "asterisk.h"
00028 
00029 ASTERISK_FILE_VERSION(__FILE__, "$Revision: 233782 $")
00030 
00031 #include <unistd.h>
00032 #include <netinet/in.h>
00033 #include <arpa/inet.h>
00034 #include <stdlib.h>
00035 #include <sys/time.h>
00036 #include <stdio.h>
00037 #include <errno.h>
00038 #include <string.h>
00039 
00040 #include "asterisk/lock.h"
00041 #include "asterisk/channel.h"
00042 #include "asterisk/file.h"
00043 #include "asterisk/logger.h"
00044 #include "asterisk/sched.h"
00045 #include "asterisk/module.h"
00046 #include "asterisk/endian.h"
00047 
00048 /* Some Ideas for this code came from makeh264e.c by Jeffrey Chilton */
00049 
00050 /* Portions of the conversion code are by guido@sienanet.it */
00051 /*! \todo Check this buf size estimate, it may be totally wrong for large frame video */
00052 
00053 #define BUF_SIZE  4096  /* Two Real h264 Frames */
00054 struct h264_desc {
00055    unsigned int lastts;
00056 };
00057 
00058 static int h264_open(struct ast_filestream *s)
00059 {
00060    unsigned int ts;
00061    int res;
00062    if ((res = fread(&ts, 1, sizeof(ts), s->f)) < sizeof(ts)) {
00063       ast_log(LOG_WARNING, "Empty file!\n");
00064       return -1;
00065    }
00066    return 0;
00067 }
00068 
00069 static struct ast_frame *h264_read(struct ast_filestream *s, int *whennext)
00070 {
00071    int res;
00072    int mark=0;
00073    unsigned short len;
00074    unsigned int ts;
00075    struct h264_desc *fs = (struct h264_desc *)s->_private;
00076 
00077    /* Send a frame from the file to the appropriate channel */
00078    if ((res = fread(&len, 1, sizeof(len), s->f)) < 1)
00079       return NULL;
00080    len = ntohs(len);
00081    mark = (len & 0x8000) ? 1 : 0;
00082    len &= 0x7fff;
00083    if (len > BUF_SIZE) {
00084       ast_log(LOG_WARNING, "Length %d is too long\n", len);
00085       len = BUF_SIZE;   /* XXX truncate */
00086    }
00087    s->fr.frametype = AST_FRAME_VIDEO;
00088    s->fr.subclass = AST_FORMAT_H264;
00089    s->fr.mallocd = 0;
00090    AST_FRAME_SET_BUFFER(&s->fr, s->buf, AST_FRIENDLY_OFFSET, len);
00091    if ((res = fread(s->fr.data, 1, s->fr.datalen, s->f)) != s->fr.datalen) {
00092       if (res)
00093          ast_log(LOG_WARNING, "Short read (%d of %d) (%s)!\n", res, len, strerror(errno));
00094       return NULL;
00095    }
00096    s->fr.samples = fs->lastts;
00097    s->fr.datalen = len;
00098    s->fr.subclass |= mark;
00099    s->fr.delivery.tv_sec = 0;
00100    s->fr.delivery.tv_usec = 0;
00101    if ((res = fread(&ts, 1, sizeof(ts), s->f)) == sizeof(ts)) {
00102       fs->lastts = ntohl(ts);
00103       *whennext = fs->lastts * 4/45;
00104    } else
00105       *whennext = 0;
00106    return &s->fr;
00107 }
00108 
00109 static int h264_write(struct ast_filestream *s, struct ast_frame *f)
00110 {
00111    int res;
00112    unsigned int ts;
00113    unsigned short len;
00114    int mark;
00115 
00116    if (f->frametype != AST_FRAME_VIDEO) {
00117       ast_log(LOG_WARNING, "Asked to write non-video frame!\n");
00118       return -1;
00119    }
00120    mark = (f->subclass & 0x1) ? 0x8000 : 0;
00121    if ((f->subclass & ~0x1) != AST_FORMAT_H264) {
00122       ast_log(LOG_WARNING, "Asked to write non-h264 frame (%d)!\n", f->subclass);
00123       return -1;
00124    }
00125    ts = htonl(f->samples);
00126    if ((res = fwrite(&ts, 1, sizeof(ts), s->f)) != sizeof(ts)) {
00127       ast_log(LOG_WARNING, "Bad write (%d/4): %s\n", res, strerror(errno));
00128       return -1;
00129    }
00130    len = htons(f->datalen | mark);
00131    if ((res = fwrite(&len, 1, sizeof(len), s->f)) != sizeof(len)) {
00132       ast_log(LOG_WARNING, "Bad write (%d/2): %s\n", res, strerror(errno));
00133       return -1;
00134    }
00135    if ((res = fwrite(f->data, 1, f->datalen, s->f)) != f->datalen) {
00136       ast_log(LOG_WARNING, "Bad write (%d/%d): %s\n", res, f->datalen, strerror(errno));
00137       return -1;
00138    }
00139    return 0;
00140 }
00141 
00142 static int h264_seek(struct ast_filestream *fs, off_t sample_offset, int whence)
00143 {
00144    /* No way Jose */
00145    return -1;
00146 }
00147 
00148 static int h264_trunc(struct ast_filestream *fs)
00149 {
00150    /* Truncate file to current length */
00151    if (ftruncate(fileno(fs->f), ftell(fs->f)) < 0)
00152       return -1;
00153    return 0;
00154 }
00155 
00156 static off_t h264_tell(struct ast_filestream *fs)
00157 {
00158    off_t offset = ftell(fs->f);
00159    return offset; /* XXX totally bogus, needs fixing */
00160 }
00161 
00162 static const struct ast_format h264_f = {
00163    .name = "h264",
00164    .exts = "h264",
00165    .format = AST_FORMAT_H264,
00166    .open = h264_open,
00167    .write = h264_write,
00168    .seek = h264_seek,
00169    .trunc = h264_trunc,
00170    .tell = h264_tell,
00171    .read = h264_read,
00172    .buf_size = BUF_SIZE + AST_FRIENDLY_OFFSET,
00173    .desc_size = sizeof(struct h264_desc),
00174 };
00175 
00176 static int load_module(void)
00177 {
00178    return ast_format_register(&h264_f);
00179 }
00180 
00181 static int unload_module(void)
00182 {
00183    return ast_format_unregister(h264_f.name);
00184 }  
00185 
00186 AST_MODULE_INFO(ASTERISK_GPL_KEY, AST_MODFLAG_LOAD_FIRST, "Raw H.264 data",
00187    .load = load_module,
00188    .unload = unload_module,
00189 );

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