mirror of https://git.ffmpeg.org/ffmpeg.git
123 lines
3.8 KiB
C
123 lines
3.8 KiB
C
/*
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* RCWT (Raw Captions With Time) demuxer
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*
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* This file is part of FFmpeg.
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*
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* FFmpeg is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* FFmpeg is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with FFmpeg; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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/*
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* RCWT (Raw Captions With Time) is a format native to ccextractor, a commonly
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* used open source tool for processing 608/708 Closed Captions (CC) sources.
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*
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* This demuxer implements the specification as of March 2024, which has
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* been stable and unchanged since April 2014.
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*
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* A free specification of RCWT can be found here:
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* @url{https://github.com/CCExtractor/ccextractor/blob/master/docs/BINARY_FILE_FORMAT.TXT}
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*/
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#include "avformat.h"
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#include "demux.h"
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#include "internal.h"
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#include "subtitles.h"
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#include "libavutil/intreadwrite.h"
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#define RCWT_HEADER_SIZE 11
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typedef struct RCWTContext {
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FFDemuxSubtitlesQueue q;
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} RCWTContext;
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static int rcwt_read_header(AVFormatContext *avf)
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{
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RCWTContext *rcwt = avf->priv_data;
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AVStream *st;
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uint8_t header[RCWT_HEADER_SIZE];
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int ret;
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/* read header */
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ret = ffio_read_size(avf->pb, header, RCWT_HEADER_SIZE);
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if (ret < 0)
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return ret;
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if (AV_RB16(header + 6) != 0x0001) {
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av_log(avf, AV_LOG_ERROR, "RCWT format version is not compatible "
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"(only version 0.001 is known)\n");
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return AVERROR_INVALIDDATA;
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}
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av_log(avf, AV_LOG_DEBUG, "RCWT writer application: %02X version: %02x\n",
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header[3], header[5]);
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/* setup stream */
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st = avformat_new_stream(avf, NULL);
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if (!st)
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return AVERROR(ENOMEM);
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st->codecpar->codec_type = AVMEDIA_TYPE_SUBTITLE;
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st->codecpar->codec_id = AV_CODEC_ID_EIA_608;
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avpriv_set_pts_info(st, 64, 1, 1000);
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/* demux */
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while (!avio_feof(avf->pb)) {
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AVPacket *sub;
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int64_t cluster_pos = avio_tell(avf->pb);
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int64_t cluster_pts = avio_rl64(avf->pb);
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int cluster_nb_blocks = avio_rl16(avf->pb);
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if (cluster_nb_blocks == 0)
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continue;
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sub = ff_subtitles_queue_insert(&rcwt->q, NULL, 0, 0);
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if (!sub)
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return AVERROR(ENOMEM);
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ret = av_get_packet(avf->pb, sub, cluster_nb_blocks * 3);
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if (ret < 0)
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return ret;
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sub->pos = cluster_pos;
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sub->pts = cluster_pts;
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}
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ff_subtitles_queue_finalize(avf, &rcwt->q);
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return 0;
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}
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static int rcwt_probe(const AVProbeData *p)
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{
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return p->buf_size > RCWT_HEADER_SIZE &&
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AV_RB16(p->buf) == 0xCCCC &&
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AV_RB8(p->buf + 2) == 0xED &&
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AV_RB16(p->buf + 6) == 0x0001 ? 50 : 0;
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}
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const FFInputFormat ff_rcwt_demuxer = {
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.p.name = "rcwt",
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.p.long_name = NULL_IF_CONFIG_SMALL("RCWT (Raw Captions With Time)"),
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.p.flags = AVFMT_TS_DISCONT,
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.priv_data_size = sizeof(RCWTContext),
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.flags_internal = FF_INFMT_FLAG_INIT_CLEANUP,
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.read_probe = rcwt_probe,
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.read_header = rcwt_read_header,
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.read_packet = ff_subtitles_read_packet,
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.read_seek2 = ff_subtitles_read_seek,
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.read_close = ff_subtitles_read_close
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};
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