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/*
* RCWT (Raw Captions With Time) demuxer
*
* This file is part of FFmpeg.
*
* FFmpeg 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.
*
* FFmpeg 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 FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
/*
* RCWT (Raw Captions With Time) is a format native to ccextractor, a commonly
* used open source tool for processing 608/708 Closed Captions (CC) sources.
*
* This demuxer implements the specification as of March 2024, which has
* been stable and unchanged since April 2014.
*
* A free specification of RCWT can be found here:
* @url{https://github.com/CCExtractor/ccextractor/blob/master/docs/BINARY_FILE_FORMAT.TXT}
*/
#include "avformat.h"
#include "demux.h"
#include "internal.h"
#include "subtitles.h"
#include "libavutil/intreadwrite.h"
#define RCWT_HEADER_SIZE 11
typedef struct RCWTContext {
FFDemuxSubtitlesQueue q;
} RCWTContext;
static int rcwt_read_header(AVFormatContext *avf)
{
RCWTContext *rcwt = avf->priv_data;
AVStream *st;
uint8_t header[RCWT_HEADER_SIZE];
int ret;
/* read header */
ret = ffio_read_size(avf->pb, header, RCWT_HEADER_SIZE);
if (ret < 0)
return ret;
if (AV_RB16(header + 6) != 0x0001) {
av_log(avf, AV_LOG_ERROR, "RCWT format version is not compatible "
"(only version 0.001 is known)\n");
return AVERROR_INVALIDDATA;
}
av_log(avf, AV_LOG_DEBUG, "RCWT writer application: %02X version: %02x\n",
header[3], header[5]);
/* setup stream */
st = avformat_new_stream(avf, NULL);
if (!st)
return AVERROR(ENOMEM);
st->codecpar->codec_type = AVMEDIA_TYPE_SUBTITLE;
st->codecpar->codec_id = AV_CODEC_ID_EIA_608;
avpriv_set_pts_info(st, 64, 1, 1000);
/* demux */
while (!avio_feof(avf->pb)) {
AVPacket *sub;
int64_t cluster_pos = avio_tell(avf->pb);
int64_t cluster_pts = avio_rl64(avf->pb);
int cluster_nb_blocks = avio_rl16(avf->pb);
if (cluster_nb_blocks == 0)
continue;
sub = ff_subtitles_queue_insert(&rcwt->q, NULL, 0, 0);
if (!sub)
return AVERROR(ENOMEM);
ret = av_get_packet(avf->pb, sub, cluster_nb_blocks * 3);
if (ret < 0)
return ret;
sub->pos = cluster_pos;
sub->pts = cluster_pts;
}
ff_subtitles_queue_finalize(avf, &rcwt->q);
return 0;
}
static int rcwt_probe(const AVProbeData *p)
{
return p->buf_size > RCWT_HEADER_SIZE &&
AV_RB16(p->buf) == 0xCCCC &&
AV_RB8(p->buf + 2) == 0xED &&
AV_RB16(p->buf + 6) == 0x0001 ? 50 : 0;
}
const FFInputFormat ff_rcwt_demuxer = {
.p.name = "rcwt",
.p.long_name = NULL_IF_CONFIG_SMALL("RCWT (Raw Captions With Time)"),
.p.flags = AVFMT_TS_DISCONT,
.priv_data_size = sizeof(RCWTContext),
.flags_internal = FF_INFMT_FLAG_INIT_CLEANUP,
.read_probe = rcwt_probe,
.read_header = rcwt_read_header,
.read_packet = ff_subtitles_read_packet,
.read_seek2 = ff_subtitles_read_seek,
.read_close = ff_subtitles_read_close
};
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