ffmpeg/libavformat/mpjpegdec.c

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/*
* Multipart JPEG format
* Copyright (c) 2015 Luca Barbato
*
* This file is part of Libav.
*
* Libav is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* Libav is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with Libav; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include "libavutil/avstring.h"
#include "avformat.h"
#include "internal.h"
static int get_line(AVIOContext *pb, char *line, int line_size)
{
int i = ff_get_line(pb, line, line_size);
if (i > 1 && line[i - 2] == '\r')
line[i - 2] = '\0';
if (pb->error)
return pb->error;
if (pb->eof_reached)
return AVERROR_EOF;
return 0;
}
static int split_tag_value(char **tag, char **value, char *line)
{
char *p = line;
while (*p != '\0' && *p != ':')
p++;
if (*p != ':')
return AVERROR_INVALIDDATA;
*p = '\0';
*tag = line;
p++;
while (av_isspace(*p))
p++;
*value = p;
return 0;
}
static int check_content_type(char *line)
{
char *tag, *value;
int ret = split_tag_value(&tag, &value, line);
if (ret < 0)
return ret;
if (av_strcasecmp(tag, "Content-type") ||
av_strcasecmp(value, "image/jpeg"))
return AVERROR_INVALIDDATA;
return 0;
}
static int mpjpeg_read_probe(AVProbeData *p)
{
AVIOContext *pb;
char line[128] = { 0 };
int ret = 0;
if (p->buf_size < 2 || p->buf[0] != '-' || p->buf[1] != '-')
return 0;
pb = avio_alloc_context(p->buf, p->buf_size, 0, NULL, NULL, NULL, NULL);
if (!pb)
return AVERROR(ENOMEM);
while (!pb->eof_reached) {
ret = get_line(pb, line, sizeof(line));
if (ret < 0)
break;
ret = check_content_type(line);
if (!ret) {
ret = AVPROBE_SCORE_MAX;
break;
}
}
av_free(pb);
return ret;
}
static int mpjpeg_read_header(AVFormatContext *s)
{
AVStream *st;
char boundary[70 + 2 + 1];
int64_t pos = avio_tell(s->pb);
int ret;
ret = get_line(s->pb, boundary, sizeof(boundary));
if (ret < 0)
return ret;
if (strncmp(boundary, "--", 2))
return AVERROR_INVALIDDATA;
st = avformat_new_stream(s, NULL);
if (!st)
return AVERROR(ENOMEM);
lavf: replace AVStream.codec with AVStream.codecpar Currently, AVStream contains an embedded AVCodecContext instance, which is used by demuxers to export stream parameters to the caller and by muxers to receive stream parameters from the caller. It is also used internally as the codec context that is passed to parsers. In addition, it is also widely used by the callers as the decoding (when demuxer) or encoding (when muxing) context, though this has been officially discouraged since Libav 11. There are multiple important problems with this approach: - the fields in AVCodecContext are in general one of * stream parameters * codec options * codec state However, it's not clear which ones are which. It is consequently unclear which fields are a demuxer allowed to set or a muxer allowed to read. This leads to erratic behaviour depending on whether decoding or encoding is being performed or not (and whether it uses the AVStream embedded codec context). - various synchronization issues arising from the fact that the same context is used by several different APIs (muxers/demuxers, parsers, bitstream filters and encoders/decoders) simultaneously, with there being no clear rules for who can modify what and the different processes being typically delayed with respect to each other. - avformat_find_stream_info() making it necessary to support opening and closing a single codec context multiple times, thus complicating the semantics of freeing various allocated objects in the codec context. Those problems are resolved by replacing the AVStream embedded codec context with a newly added AVCodecParameters instance, which stores only the stream parameters exported by the demuxers or read by the muxers.
2014-06-18 18:42:52 +00:00
st->codecpar->codec_type = AVMEDIA_TYPE_VIDEO;
st->codecpar->codec_id = AV_CODEC_ID_MJPEG;
avpriv_set_pts_info(st, 60, 1, 25);
avio_seek(s->pb, pos, SEEK_SET);
return 0;
}
static int parse_content_length(const char *value)
{
long int val = strtol(value, NULL, 10);
if (val == LONG_MIN || val == LONG_MAX)
return AVERROR(errno);
if (val > INT_MAX)
return AVERROR(ERANGE);
return val;
}
static int parse_multipart_header(AVFormatContext *s)
{
char line[128];
int found_content_type = 0;
int ret, size = -1;
// get the CRLF as empty string
ret = get_line(s->pb, line, sizeof(line));
if (ret < 0)
return ret;
/* some implementation do not provide the required
* initial CRLF (see rfc1341 7.2.1)
*/
if (!line[0]) {
ret = get_line(s->pb, line, sizeof(line));
if (ret < 0)
return ret;
}
if (strncmp(line, "--", 2))
return AVERROR_INVALIDDATA;
while (!s->pb->eof_reached) {
char *tag, *value;
ret = get_line(s->pb, line, sizeof(line));
if (ret < 0)
return ret;
if (line[0] == '\0')
break;
ret = split_tag_value(&tag, &value, line);
if (ret < 0)
return ret;
if (!av_strcasecmp(tag, "Content-type")) {
if (av_strcasecmp(value, "image/jpeg")) {
av_log(s, AV_LOG_ERROR,
"Unexpected %s : %s\n",
tag, value);
return AVERROR_INVALIDDATA;
} else
found_content_type = 1;
} else if (!av_strcasecmp(tag, "Content-Length")) {
size = parse_content_length(value);
if (size < 0)
return size;
}
}
if (!found_content_type || size < 0) {
return AVERROR_INVALIDDATA;
}
return size;
}
static int mpjpeg_read_packet(AVFormatContext *s, AVPacket *pkt)
{
int ret;
int size = parse_multipart_header(s);
if (size < 0)
return size;
ret = av_get_packet(s->pb, pkt, size);
if (ret < 0)
return ret;
return 0;
}
AVInputFormat ff_mpjpeg_demuxer = {
.name = "mpjpeg",
.long_name = NULL_IF_CONFIG_SMALL("MIME multipart JPEG"),
.mime_type = "multipart/x-mixed-replace",
.extensions = "mjpg",
.read_probe = mpjpeg_read_probe,
.read_header = mpjpeg_read_header,
.read_packet = mpjpeg_read_packet,
};