format_h263.c

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/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 1999 - 2006, Digium, Inc.
 *
 * Mark Spencer <markster@digium.com>
 *
 * 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 guido@sienanet.it */
 
/* 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
);