[FFmpeg-devel] [PATCH v5 1/4] avformat/rcwtdec: add RCWT Closed Captions demuxer
Marth64
marth64 at proxyid.net
Tue Mar 19 19:39:10 EET 2024
Signed-off-by: Marth64 <marth64 at proxyid.net>
---
Changelog | 2 +-
doc/demuxers.texi | 29 ++++++++
libavformat/Makefile | 1 +
libavformat/allformats.c | 1 +
libavformat/rcwtdec.c | 148 +++++++++++++++++++++++++++++++++++++++
5 files changed, 180 insertions(+), 1 deletion(-)
create mode 100644 libavformat/rcwtdec.c
diff --git a/Changelog b/Changelog
index e3ca52430c..be871f75cd 100644
--- a/Changelog
+++ b/Changelog
@@ -19,7 +19,7 @@ version <next>:
- lavu/eval: introduce randomi() function in expressions
- VVC decoder
- fsync filter
-- Raw Captions with Time (RCWT) closed caption muxer
+- Raw Captions with Time (RCWT) closed caption muxer and demuxer
- ffmpeg CLI -bsf option may now be used for input as well as output
- ffmpeg CLI options may now be used as -/opt <path>, which is equivalent
to -opt <contents of file <path>>
diff --git a/doc/demuxers.texi b/doc/demuxers.texi
index b70f3a38d7..26d4ba18a1 100644
--- a/doc/demuxers.texi
+++ b/doc/demuxers.texi
@@ -1038,6 +1038,35 @@ the command:
ffplay -f rawvideo -pixel_format rgb24 -video_size 320x240 -framerate 10 input.raw
@end example
+ at anchor{rcwtdec}
+ at section rcwt
+
+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.
+It can be used to archive the original, raw CC bitstream and to produce
+a source file for later CC processing or conversion. This demuxer can process
+RCWT sources created by ccextractor or FFmpeg. For more information on the format,
+see @ref{rcwtenc,,,ffmpeg-formats}.
+
+This demuxer implements the specification as of March 2024, which has
+been stable and unchanged since April 2014.
+
+ at subsection Examples
+
+ at itemize
+ at item
+Render Closed Captions to ASSA (using FFmpeg's CC decoder):
+ at example
+ffmpeg -i CC.rcwt.bin CC.ass
+ at end example
+
+ at item
+Convert an RCWT backup to SCC:
+ at example
+ffmpeg -i CC.rcwt.bin -c:s copy CC.scc
+ at end example
+ at end itemize
+
@section sbg
SBaGen script demuxer.
diff --git a/libavformat/Makefile b/libavformat/Makefile
index 94a949f555..a6de720d8c 100644
--- a/libavformat/Makefile
+++ b/libavformat/Makefile
@@ -493,6 +493,7 @@ OBJS-$(CONFIG_QOA_DEMUXER) += qoadec.o
OBJS-$(CONFIG_R3D_DEMUXER) += r3d.o
OBJS-$(CONFIG_RAWVIDEO_DEMUXER) += rawvideodec.o
OBJS-$(CONFIG_RAWVIDEO_MUXER) += rawenc.o
+OBJS-$(CONFIG_RCWT_DEMUXER) += rcwtdec.o subtitles.o
OBJS-$(CONFIG_RCWT_MUXER) += rcwtenc.o subtitles.o
OBJS-$(CONFIG_REALTEXT_DEMUXER) += realtextdec.o subtitles.o
OBJS-$(CONFIG_REDSPARK_DEMUXER) += redspark.o
diff --git a/libavformat/allformats.c b/libavformat/allformats.c
index e15d0fa6d7..3140018f8d 100644
--- a/libavformat/allformats.c
+++ b/libavformat/allformats.c
@@ -391,6 +391,7 @@ extern const FFInputFormat ff_qoa_demuxer;
extern const FFInputFormat ff_r3d_demuxer;
extern const FFInputFormat ff_rawvideo_demuxer;
extern const FFOutputFormat ff_rawvideo_muxer;
+extern const FFInputFormat ff_rcwt_demuxer;
extern const FFOutputFormat ff_rcwt_muxer;
extern const FFInputFormat ff_realtext_demuxer;
extern const FFInputFormat ff_redspark_demuxer;
diff --git a/libavformat/rcwtdec.c b/libavformat/rcwtdec.c
new file mode 100644
index 0000000000..1baa571231
--- /dev/null
+++ b/libavformat/rcwtdec.c
@@ -0,0 +1,148 @@
+/*
+ * 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_CLUSTER_MAX_BLOCKS 65535
+#define RCWT_BLOCK_SIZE 3
+#define RCWT_HEADER_SIZE 11
+
+typedef struct RCWTContext {
+ FFDemuxSubtitlesQueue q;
+} RCWTContext;
+
+static int rcwt_read_header(AVFormatContext *avf)
+{
+ RCWTContext *rcwt = avf->priv_data;
+
+ AVPacket *sub = NULL;
+ AVStream *st;
+ uint8_t header[RCWT_HEADER_SIZE] = {0};
+ int nb_bytes = 0;
+
+ /* validate the header */
+ nb_bytes = avio_read(avf->pb, header, RCWT_HEADER_SIZE);
+ if (nb_bytes != RCWT_HEADER_SIZE) {
+ av_log(avf, AV_LOG_ERROR, "Header does not have the expected size "
+ "(expected=%d actual=%d)\n",
+ RCWT_HEADER_SIZE, nb_bytes);
+ return AVERROR_INVALIDDATA;
+ }
+
+ 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 AVStream */
+ 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)) {
+ int64_t cluster_pts = AV_NOPTS_VALUE;
+ int cluster_nb_blocks = 0;
+ int cluster_size = 0;
+ uint8_t *cluster_buf;
+
+ cluster_pts = avio_rl64(avf->pb);
+ cluster_nb_blocks = avio_rl16(avf->pb);
+ if (cluster_nb_blocks == 0)
+ continue;
+
+ cluster_size = cluster_nb_blocks * RCWT_BLOCK_SIZE;
+ cluster_buf = av_malloc(cluster_size);
+ if (!cluster_buf)
+ return AVERROR(ENOMEM);
+
+ nb_bytes = avio_read(avf->pb, cluster_buf, cluster_size);
+ if (nb_bytes < 0)
+ return nb_bytes;
+
+ if (nb_bytes != cluster_size) {
+ av_freep(&cluster_buf);
+ av_log(avf, AV_LOG_ERROR, "Cluster does not have the expected size "
+ "(expected=%d actual=%d pos=%ld)\n",
+ cluster_size, nb_bytes, avio_tell(avf->pb));
+ return AVERROR_INVALIDDATA;
+ }
+
+ sub = ff_subtitles_queue_insert(&rcwt->q, cluster_buf, cluster_size, 0);
+ if (!sub) {
+ av_freep(&cluster_buf);
+ return AVERROR(ENOMEM);
+ }
+
+ sub->pos = avio_tell(avf->pb);
+ sub->pts = cluster_pts;
+
+ av_freep(&cluster_buf);
+ cluster_buf = NULL;
+ }
+
+ 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 ? 50 : 0;
+}
+
+const FFInputFormat ff_rcwt_demuxer = {
+ .p.name = "rcwt",
+ .p.long_name = NULL_IF_CONFIG_SMALL("RCWT (Raw Captions With Time)"),
+ .p.extensions = "bin",
+ .p.flags = AVFMT_TS_DISCONT,
+ .priv_data_size = sizeof(RCWTContext),
+ .flags_internal = FF_FMT_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
+};
--
2.34.1
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