Fri Aug 17 00:17:16 2018

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 /*** MODULEINFO
00028    <support_level>core</support_level>
00029  ***/
00030  
00031 #include "asterisk.h"
00032 
00033 ASTERISK_FILE_VERSION(__FILE__, "$Revision: 364578 $")
00034 
00035 #include "asterisk/mod_format.h"
00036 #include "asterisk/module.h"
00037 #include "asterisk/endian.h"
00038 
00039 /* Some Ideas for this code came from makeh264e.c by Jeffrey Chilton */
00040 
00041 /* Portions of the conversion code are by guido@sienanet.it */
00042 /*! \todo Check this buf size estimate, it may be totally wrong for large frame video */
00043 
00044 #define BUF_SIZE  4096  /* Two Real h264 Frames */
00045 struct h264_desc {
00046    unsigned int lastts;
00047 };
00048 
00049 static int h264_open(struct ast_filestream *s)
00050 {
00051    unsigned int ts;
00052    int res;
00053    if ((res = fread(&ts, 1, sizeof(ts), s->f)) < sizeof(ts)) {
00054       ast_log(LOG_WARNING, "Empty file!\n");
00055       return -1;
00056    }
00057    return 0;
00058 }
00059 
00060 static struct ast_frame *h264_read(struct ast_filestream *s, int *whennext)
00061 {
00062    int res;
00063    int mark=0;
00064    unsigned short len;
00065    unsigned int ts;
00066    struct h264_desc *fs = (struct h264_desc *)s->_private;
00067 
00068    /* Send a frame from the file to the appropriate channel */
00069    if ((res = fread(&len, 1, sizeof(len), s->f)) < 1)
00070       return NULL;
00071    len = ntohs(len);
00072    mark = (len & 0x8000) ? 1 : 0;
00073    len &= 0x7fff;
00074    if (len > BUF_SIZE) {
00075       ast_log(LOG_WARNING, "Length %d is too long\n", len);
00076       len = BUF_SIZE;   /* XXX truncate */
00077    }
00078    s->fr.frametype = AST_FRAME_VIDEO;
00079    s->fr.subclass.codec = AST_FORMAT_H264;
00080    s->fr.mallocd = 0;
00081    AST_FRAME_SET_BUFFER(&s->fr, s->buf, AST_FRIENDLY_OFFSET, len);
00082    if ((res = fread(s->fr.data.ptr, 1, s->fr.datalen, s->f)) != s->fr.datalen) {
00083       if (res)
00084          ast_log(LOG_WARNING, "Short read (%d of %d) (%s)!\n", res, len, strerror(errno));
00085       return NULL;
00086    }
00087    s->fr.samples = fs->lastts;
00088    s->fr.datalen = len;
00089    s->fr.subclass.codec |= mark;
00090    s->fr.delivery.tv_sec = 0;
00091    s->fr.delivery.tv_usec = 0;
00092    if ((res = fread(&ts, 1, sizeof(ts), s->f)) == sizeof(ts)) {
00093       fs->lastts = ntohl(ts);
00094       *whennext = fs->lastts * 4/45;
00095    } else
00096       *whennext = 0;
00097    return &s->fr;
00098 }
00099 
00100 static int h264_write(struct ast_filestream *s, struct ast_frame *f)
00101 {
00102    int res;
00103    unsigned int ts;
00104    unsigned short len;
00105    int mark;
00106 
00107    if (f->frametype != AST_FRAME_VIDEO) {
00108       ast_log(LOG_WARNING, "Asked to write non-video frame!\n");
00109       return -1;
00110    }
00111    mark = (f->subclass.codec & 0x1) ? 0x8000 : 0;
00112    if ((f->subclass.codec & ~0x1) != AST_FORMAT_H264) {
00113       ast_log(LOG_WARNING, "Asked to write non-h264 frame (%s)!\n", ast_getformatname(f->subclass.codec));
00114       return -1;
00115    }
00116    ts = htonl(f->samples);
00117    if ((res = fwrite(&ts, 1, sizeof(ts), s->f)) != sizeof(ts)) {
00118       ast_log(LOG_WARNING, "Bad write (%d/4): %s\n", res, strerror(errno));
00119       return -1;
00120    }
00121    len = htons(f->datalen | mark);
00122    if ((res = fwrite(&len, 1, sizeof(len), s->f)) != sizeof(len)) {
00123       ast_log(LOG_WARNING, "Bad write (%d/2): %s\n", res, strerror(errno));
00124       return -1;
00125    }
00126    if ((res = fwrite(f->data.ptr, 1, f->datalen, s->f)) != f->datalen) {
00127       ast_log(LOG_WARNING, "Bad write (%d/%d): %s\n", res, f->datalen, strerror(errno));
00128       return -1;
00129    }
00130    return 0;
00131 }
00132 
00133 static int h264_seek(struct ast_filestream *fs, off_t sample_offset, int whence)
00134 {
00135    /* No way Jose */
00136    return -1;
00137 }
00138 
00139 static int h264_trunc(struct ast_filestream *fs)
00140 {
00141    int fd;
00142    off_t cur;
00143 
00144    if ((fd = fileno(fs->f)) < 0) {
00145       ast_log(AST_LOG_WARNING, "Unable to determine file descriptor for h264 filestream %p: %s\n", fs, strerror(errno));
00146       return -1;
00147    }
00148    if ((cur = ftello(fs->f)) < 0) {
00149       ast_log(AST_LOG_WARNING, "Unable to determine current position in h264 filestream %p: %s\n", fs, strerror(errno));
00150       return -1;
00151    }
00152    /* Truncate file to current length */
00153    return ftruncate(fd, cur);
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    if (ast_format_register(&h264_f))
00179       return AST_MODULE_LOAD_FAILURE;
00180    return AST_MODULE_LOAD_SUCCESS;
00181 }
00182 
00183 static int unload_module(void)
00184 {
00185    return ast_format_unregister(h264_f.name);
00186 }
00187 
00188 AST_MODULE_INFO(ASTERISK_GPL_KEY, AST_MODFLAG_LOAD_ORDER, "Raw H.264 data",
00189    .load = load_module,
00190    .unload = unload_module,
00191    .load_pri = AST_MODPRI_APP_DEPEND
00192 );

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