Wed Oct 28 11:45:37 2009

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: 90158 $")
00030 
00031 #include "asterisk/mod_format.h"
00032 #include "asterisk/module.h"
00033 #include "asterisk/endian.h"
00034 
00035 /* Some Ideas for this code came from makeh264e.c by Jeffrey Chilton */
00036 
00037 /* Portions of the conversion code are by guido@sienanet.it */
00038 /*! \todo Check this buf size estimate, it may be totally wrong for large frame video */
00039 
00040 #define BUF_SIZE  4096  /* Two Real h264 Frames */
00041 struct h264_desc {
00042    unsigned int lastts;
00043 };
00044 
00045 static int h264_open(struct ast_filestream *s)
00046 {
00047    unsigned int ts;
00048    int res;
00049    if ((res = fread(&ts, 1, sizeof(ts), s->f)) < sizeof(ts)) {
00050       ast_log(LOG_WARNING, "Empty file!\n");
00051       return -1;
00052    }
00053    return 0;
00054 }
00055 
00056 static struct ast_frame *h264_read(struct ast_filestream *s, int *whennext)
00057 {
00058    int res;
00059    int mark=0;
00060    unsigned short len;
00061    unsigned int ts;
00062    struct h264_desc *fs = (struct h264_desc *)s->_private;
00063 
00064    /* Send a frame from the file to the appropriate channel */
00065    if ((res = fread(&len, 1, sizeof(len), s->f)) < 1)
00066       return NULL;
00067    len = ntohs(len);
00068    mark = (len & 0x8000) ? 1 : 0;
00069    len &= 0x7fff;
00070    if (len > BUF_SIZE) {
00071       ast_log(LOG_WARNING, "Length %d is too long\n", len);
00072       len = BUF_SIZE;   /* XXX truncate */
00073    }
00074    s->fr.frametype = AST_FRAME_VIDEO;
00075    s->fr.subclass = AST_FORMAT_H264;
00076    s->fr.mallocd = 0;
00077    AST_FRAME_SET_BUFFER(&s->fr, s->buf, AST_FRIENDLY_OFFSET, len);
00078    if ((res = fread(s->fr.data, 1, s->fr.datalen, s->f)) != s->fr.datalen) {
00079       if (res)
00080          ast_log(LOG_WARNING, "Short read (%d of %d) (%s)!\n", res, len, strerror(errno));
00081       return NULL;
00082    }
00083    s->fr.samples = fs->lastts;
00084    s->fr.datalen = len;
00085    s->fr.subclass |= mark;
00086    s->fr.delivery.tv_sec = 0;
00087    s->fr.delivery.tv_usec = 0;
00088    if ((res = fread(&ts, 1, sizeof(ts), s->f)) == sizeof(ts)) {
00089       fs->lastts = ntohl(ts);
00090       *whennext = fs->lastts * 4/45;
00091    } else
00092       *whennext = 0;
00093    return &s->fr;
00094 }
00095 
00096 static int h264_write(struct ast_filestream *s, struct ast_frame *f)
00097 {
00098    int res;
00099    unsigned int ts;
00100    unsigned short len;
00101    int mark;
00102 
00103    if (f->frametype != AST_FRAME_VIDEO) {
00104       ast_log(LOG_WARNING, "Asked to write non-video frame!\n");
00105       return -1;
00106    }
00107    mark = (f->subclass & 0x1) ? 0x8000 : 0;
00108    if ((f->subclass & ~0x1) != AST_FORMAT_H264) {
00109       ast_log(LOG_WARNING, "Asked to write non-h264 frame (%d)!\n", f->subclass);
00110       return -1;
00111    }
00112    ts = htonl(f->samples);
00113    if ((res = fwrite(&ts, 1, sizeof(ts), s->f)) != sizeof(ts)) {
00114       ast_log(LOG_WARNING, "Bad write (%d/4): %s\n", res, strerror(errno));
00115       return -1;
00116    }
00117    len = htons(f->datalen | mark);
00118    if ((res = fwrite(&len, 1, sizeof(len), s->f)) != sizeof(len)) {
00119       ast_log(LOG_WARNING, "Bad write (%d/2): %s\n", res, strerror(errno));
00120       return -1;
00121    }
00122    if ((res = fwrite(f->data, 1, f->datalen, s->f)) != f->datalen) {
00123       ast_log(LOG_WARNING, "Bad write (%d/%d): %s\n", res, f->datalen, strerror(errno));
00124       return -1;
00125    }
00126    return 0;
00127 }
00128 
00129 static int h264_seek(struct ast_filestream *fs, off_t sample_offset, int whence)
00130 {
00131    /* No way Jose */
00132    return -1;
00133 }
00134 
00135 static int h264_trunc(struct ast_filestream *fs)
00136 {
00137    /* Truncate file to current length */
00138    if (ftruncate(fileno(fs->f), ftell(fs->f)) < 0)
00139       return -1;
00140    return 0;
00141 }
00142 
00143 static off_t h264_tell(struct ast_filestream *fs)
00144 {
00145    off_t offset = ftell(fs->f);
00146    return offset; /* XXX totally bogus, needs fixing */
00147 }
00148 
00149 static const struct ast_format h264_f = {
00150    .name = "h264",
00151    .exts = "h264",
00152    .format = AST_FORMAT_H264,
00153    .open = h264_open,
00154    .write = h264_write,
00155    .seek = h264_seek,
00156    .trunc = h264_trunc,
00157    .tell = h264_tell,
00158    .read = h264_read,
00159    .buf_size = BUF_SIZE + AST_FRIENDLY_OFFSET,
00160    .desc_size = sizeof(struct h264_desc),
00161 };
00162 
00163 static int load_module(void)
00164 {
00165    if (ast_format_register(&h264_f))
00166       return AST_MODULE_LOAD_FAILURE;
00167    return AST_MODULE_LOAD_SUCCESS;
00168 }
00169 
00170 static int unload_module(void)
00171 {
00172    return ast_format_unregister(h264_f.name);
00173 }  
00174 
00175 AST_MODULE_INFO_STANDARD(ASTERISK_GPL_KEY, "Raw H.264 data");

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