format_h263.c

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/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 1999 - 2006, Digium, Inc.
 *
 * Mark Spencer <[email protected]>
 *
 * See http://www.asterisk.org for more information about
 * the Asterisk project. Please do not directly contact
 * any of the maintainers of this project for assistance;
 * the project provides a web site, mailing lists and IRC
 * channels for your use.
 *
 * This program is free software, distributed under the terms of
 * the GNU General Public License Version 2. See the LICENSE file
 * at the top of the source tree.
 */

/*! \file
 *
 * \brief Save to raw, headerless h263 data.
 * \arg File name extension: h263
 * \ingroup formats
 * \arg See \ref AstVideo
 */

/*** MODULEINFO
 <support_level>core</support_level>
 ***/

#include "asterisk.h"

#include "asterisk/mod_format.h"
#include "asterisk/module.h"
#include "asterisk/endian.h"
#include "asterisk/format_cache.h"

/* Some Ideas for this code came from makeh263e.c by Jeffrey Chilton */

/* Portions of the conversion code are by [email protected] */

/* According to:
 * http://lists.mpegif.org/pipermail/mp4-tech/2005-July/005741.html
 * the maximum actual frame size is not 2048, but 8192. Since the maximum
 * theoretical limit is not much larger (32k = 15bits), we'll go for that
 * size to ensure we don't corrupt frames sent to us (unless they're
 * ridiculously large). */
#define BUF_SIZE 32768 /* Four real h.263 Frames */

#define FRAME_ENDED 0x8000

struct h263_desc {
 unsigned int lastts;
};


static int h263_open(struct ast_filestream *s)
{
 unsigned int ts;

 if (fread(&ts, 1, sizeof(ts), s->f) != sizeof(ts)) {
 ast_log(LOG_WARNING, "Empty file!\n");
 return -1;
 }
 return 0;
}

static struct ast_frame *h263_read(struct ast_filestream *s, int *whennext)
{
 size_t res;
 uint32_t mark;
 unsigned short len;
 unsigned int ts;
 struct h263_desc *fs = (struct h263_desc *)s->_private;

 /* Send a frame from the file to the appropriate channel */
 if ((res = fread(&len, 1, sizeof(len), s->f)) != sizeof(len))
 return NULL;
 len = ntohs(len);
 mark = (len & FRAME_ENDED) ? 1 : 0;
 len &= 0x7fff;
 if (len > BUF_SIZE) {
 ast_log(LOG_WARNING, "Length %d is too long\n", len);
 return NULL;
 }
 AST_FRAME_SET_BUFFER(&s->fr, s->buf, AST_FRIENDLY_OFFSET, len);
 if ((res = fread(s->fr.data.ptr, 1, s->fr.datalen, s->f)) != s->fr.datalen) {
 if (res) {
 ast_log(LOG_WARNING, "Short read of %s data (expected %d bytes, read %zu): %s\n",
 ast_format_get_name(s->fr.subclass.format), s->fr.datalen, res,
 strerror(errno));
 }
 return NULL;
 }
 s->fr.samples = fs->lastts; /* XXX what ? */
 s->fr.datalen = len;
 s->fr.subclass.frame_ending = mark;
 if ((res = fread(&ts, 1, sizeof(ts), s->f)) == sizeof(ts)) {
 fs->lastts = ntohl(ts);
 *whennext = fs->lastts * 4/45;
 } else
 *whennext = 0;
 return &s->fr;
}

static int h263_write(struct ast_filestream *fs, struct ast_frame *f)
{
 int res;
 unsigned int ts;
 unsigned short len;
 uint32_t mark = 0;
 mark = f->subclass.frame_ending ? FRAME_ENDED : 0;
 ts = htonl(f->samples);
 if ((res = fwrite(&ts, 1, sizeof(ts), fs->f)) != sizeof(ts)) {
 ast_log(LOG_WARNING, "Bad write (%d/4): %s\n", res, strerror(errno));
 return -1;
 }
 len = htons(f->datalen | mark);
 if ((res = fwrite(&len, 1, sizeof(len), fs->f)) != sizeof(len)) {
 ast_log(LOG_WARNING, "Bad write (%d/2): %s\n", res, strerror(errno));
 return -1;
 }
 if ((res = fwrite(f->data.ptr, 1, f->datalen, fs->f)) != f->datalen) {
 ast_log(LOG_WARNING, "Bad write (%d/%d): %s\n", res, f->datalen, strerror(errno));
 return -1;
 }
 return 0;
}

static int h263_seek(struct ast_filestream *fs, off_t sample_offset, int whence)
{
 /* No way Jose */
 return -1;
}

static int h263_trunc(struct ast_filestream *fs)
{
 int fd;
 off_t cur;

 if ((fd = fileno(fs->f)) < 0) {
 ast_log(AST_LOG_WARNING, "Unable to determine file descriptor for h263 filestream %p: %s\n", fs, strerror(errno));
 return -1;
 }
 if ((cur = ftello(fs->f)) < 0) {
 ast_log(AST_LOG_WARNING, "Unable to determine current position in h263 filestream %p: %s\n", fs, strerror(errno));
 return -1;
 }
 /* Truncate file to current length */
 return ftruncate(fd, cur);
}

static off_t h263_tell(struct ast_filestream *fs)
{
 off_t offset = ftello(fs->f);
 return offset; /* XXX totally bogus, needs fixing */
}

static struct ast_format_def h263_f = {
 .name = "h263",
 .exts = "h263",
 .open = h263_open,
 .write = h263_write,
 .seek = h263_seek,
 .trunc = h263_trunc,
 .tell = h263_tell,
 .read = h263_read,
 .buf_size = BUF_SIZE + AST_FRIENDLY_OFFSET,
 .desc_size = sizeof(struct h263_desc),
};

static int load_module(void)
{
 h263_f.format = ast_format_h263;
 if (ast_format_def_register(&h263_f))
 return AST_MODULE_LOAD_DECLINE;
 return AST_MODULE_LOAD_SUCCESS;
}

static int unload_module(void)
{
 return ast_format_def_unregister(h263_f.name);
}

AST_MODULE_INFO(ASTERISK_GPL_KEY, AST_MODFLAG_LOAD_ORDER, "Raw H.263 data",
 .support_level = AST_MODULE_SUPPORT_CORE,
 .load = load_module,
 .unload = unload_module,
 .load_pri = AST_MODPRI_APP_DEPEND
);