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FFmpeg/libavformat/rcwtenc.c

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libavformat: add RCWT closed caption muxex Signed-off-by: Marth64 <marth64@proxyid.net> Raw Captions With Time (RCWT) is a format native to ccextractor, a commonly used open source tool for processing 608/708 closed caption (CC) sources. It can be used to archive the original, raw CC bitstream and to produce a source file file for later CC processing or conversion. As a result, it also allows for interopability with ccextractor for processing CC data extracted via ffmpeg. The format is simple to parse and can be used to retain all lines and variants of CC. A free specification of RCWT can be found here: https://github.com/CCExtractor/ccextractor/blob/master/docs/BINARY_FILE_FORMAT.TXT This muxer implements the specification as of 01/05/2024, which has been stable and unchanged for 10 years as of this writing. This muxer will have some nuances from the way that ccextractor muxes RCWT. No compatibility issues when processing the output with ccextractor have been observed as a result of this so far, but mileage may vary and outputs will not be a bit-exact match. Specifically, the differences are: (1) This muxer will identify as "FF" as the writing program identifier, so as to be honest about the output's origin. (2) ffmpeg's MPEG-1/2, H264, HEVC, etc. decoders extract closed captioning data differently than ccextractor from embedded SEI/user data. For example, DVD captioning bytes will be translated to ATSC A53 format. This allows ffmpeg to handle 608/708 in a consistant way downstream. This is a lossless conversion and the meaningful data is retained. (3) This muxer will not alter the extracted data except to remove invalid packets in between valid CC blocks. On the other hand, ccextractor will by default remove mid-stream padding, and add padding at the end of the stream (in order to convey the end time of the source video).
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/*
* RCWT (Raw Captions With Time) muxer
libavformat: add RCWT closed caption muxex Signed-off-by: Marth64 <marth64@proxyid.net> Raw Captions With Time (RCWT) is a format native to ccextractor, a commonly used open source tool for processing 608/708 closed caption (CC) sources. It can be used to archive the original, raw CC bitstream and to produce a source file file for later CC processing or conversion. As a result, it also allows for interopability with ccextractor for processing CC data extracted via ffmpeg. The format is simple to parse and can be used to retain all lines and variants of CC. A free specification of RCWT can be found here: https://github.com/CCExtractor/ccextractor/blob/master/docs/BINARY_FILE_FORMAT.TXT This muxer implements the specification as of 01/05/2024, which has been stable and unchanged for 10 years as of this writing. This muxer will have some nuances from the way that ccextractor muxes RCWT. No compatibility issues when processing the output with ccextractor have been observed as a result of this so far, but mileage may vary and outputs will not be a bit-exact match. Specifically, the differences are: (1) This muxer will identify as "FF" as the writing program identifier, so as to be honest about the output's origin. (2) ffmpeg's MPEG-1/2, H264, HEVC, etc. decoders extract closed captioning data differently than ccextractor from embedded SEI/user data. For example, DVD captioning bytes will be translated to ATSC A53 format. This allows ffmpeg to handle 608/708 in a consistant way downstream. This is a lossless conversion and the meaningful data is retained. (3) This muxer will not alter the extracted data except to remove invalid packets in between valid CC blocks. On the other hand, ccextractor will by default remove mid-stream padding, and add padding at the end of the stream (in order to convey the end time of the source video).
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*
* 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.
libavformat: add RCWT closed caption muxex Signed-off-by: Marth64 <marth64@proxyid.net> Raw Captions With Time (RCWT) is a format native to ccextractor, a commonly used open source tool for processing 608/708 closed caption (CC) sources. It can be used to archive the original, raw CC bitstream and to produce a source file file for later CC processing or conversion. As a result, it also allows for interopability with ccextractor for processing CC data extracted via ffmpeg. The format is simple to parse and can be used to retain all lines and variants of CC. A free specification of RCWT can be found here: https://github.com/CCExtractor/ccextractor/blob/master/docs/BINARY_FILE_FORMAT.TXT This muxer implements the specification as of 01/05/2024, which has been stable and unchanged for 10 years as of this writing. This muxer will have some nuances from the way that ccextractor muxes RCWT. No compatibility issues when processing the output with ccextractor have been observed as a result of this so far, but mileage may vary and outputs will not be a bit-exact match. Specifically, the differences are: (1) This muxer will identify as "FF" as the writing program identifier, so as to be honest about the output's origin. (2) ffmpeg's MPEG-1/2, H264, HEVC, etc. decoders extract closed captioning data differently than ccextractor from embedded SEI/user data. For example, DVD captioning bytes will be translated to ATSC A53 format. This allows ffmpeg to handle 608/708 in a consistant way downstream. This is a lossless conversion and the meaningful data is retained. (3) This muxer will not alter the extracted data except to remove invalid packets in between valid CC blocks. On the other hand, ccextractor will by default remove mid-stream padding, and add padding at the end of the stream (in order to convey the end time of the source video).
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*
* This muxer implements the specification as of March 2024, which has
* been stable and unchanged since April 2014.
libavformat: add RCWT closed caption muxex Signed-off-by: Marth64 <marth64@proxyid.net> Raw Captions With Time (RCWT) is a format native to ccextractor, a commonly used open source tool for processing 608/708 closed caption (CC) sources. It can be used to archive the original, raw CC bitstream and to produce a source file file for later CC processing or conversion. As a result, it also allows for interopability with ccextractor for processing CC data extracted via ffmpeg. The format is simple to parse and can be used to retain all lines and variants of CC. A free specification of RCWT can be found here: https://github.com/CCExtractor/ccextractor/blob/master/docs/BINARY_FILE_FORMAT.TXT This muxer implements the specification as of 01/05/2024, which has been stable and unchanged for 10 years as of this writing. This muxer will have some nuances from the way that ccextractor muxes RCWT. No compatibility issues when processing the output with ccextractor have been observed as a result of this so far, but mileage may vary and outputs will not be a bit-exact match. Specifically, the differences are: (1) This muxer will identify as "FF" as the writing program identifier, so as to be honest about the output's origin. (2) ffmpeg's MPEG-1/2, H264, HEVC, etc. decoders extract closed captioning data differently than ccextractor from embedded SEI/user data. For example, DVD captioning bytes will be translated to ATSC A53 format. This allows ffmpeg to handle 608/708 in a consistant way downstream. This is a lossless conversion and the meaningful data is retained. (3) This muxer will not alter the extracted data except to remove invalid packets in between valid CC blocks. On the other hand, ccextractor will by default remove mid-stream padding, and add padding at the end of the stream (in order to convey the end time of the source video).
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*
* This muxer will have some nuances from the way that ccextractor muxes RCWT.
* No compatibility issues when processing the output with ccextractor
* have been observed as a result of this so far, but mileage may vary
* and outputs will not be a bit-exact match.
*
* Specifically, the differences are:
* (1) This muxer will identify as "FF" as the writing program identifier, so
* as to be honest about the output's origin.
*
* (2) This muxer will not alter the extracted data except to remove invalid
libavformat: add RCWT closed caption muxex Signed-off-by: Marth64 <marth64@proxyid.net> Raw Captions With Time (RCWT) is a format native to ccextractor, a commonly used open source tool for processing 608/708 closed caption (CC) sources. It can be used to archive the original, raw CC bitstream and to produce a source file file for later CC processing or conversion. As a result, it also allows for interopability with ccextractor for processing CC data extracted via ffmpeg. The format is simple to parse and can be used to retain all lines and variants of CC. A free specification of RCWT can be found here: https://github.com/CCExtractor/ccextractor/blob/master/docs/BINARY_FILE_FORMAT.TXT This muxer implements the specification as of 01/05/2024, which has been stable and unchanged for 10 years as of this writing. This muxer will have some nuances from the way that ccextractor muxes RCWT. No compatibility issues when processing the output with ccextractor have been observed as a result of this so far, but mileage may vary and outputs will not be a bit-exact match. Specifically, the differences are: (1) This muxer will identify as "FF" as the writing program identifier, so as to be honest about the output's origin. (2) ffmpeg's MPEG-1/2, H264, HEVC, etc. decoders extract closed captioning data differently than ccextractor from embedded SEI/user data. For example, DVD captioning bytes will be translated to ATSC A53 format. This allows ffmpeg to handle 608/708 in a consistant way downstream. This is a lossless conversion and the meaningful data is retained. (3) This muxer will not alter the extracted data except to remove invalid packets in between valid CC blocks. On the other hand, ccextractor will by default remove mid-stream padding, and add padding at the end of the stream (in order to convey the end time of the source video).
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* packets in between valid CC blocks. On the other hand, ccextractor
* will by default remove mid-stream padding, and add padding at the end
* of the stream (in order to convey the end time of the source video).
*
* 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 "internal.h"
#include "mux.h"
#include "libavutil/log.h"
#include "libavutil/intreadwrite.h"
#define RCWT_CLUSTER_MAX_BLOCKS 65535
#define RCWT_BLOCK_SIZE 3
typedef struct RCWTContext {
int cluster_pos;
int64_t cluster_pts;
uint8_t cluster_buf[RCWT_CLUSTER_MAX_BLOCKS * RCWT_BLOCK_SIZE];
} RCWTContext;
static void rcwt_init_cluster(RCWTContext *rcwt)
libavformat: add RCWT closed caption muxex Signed-off-by: Marth64 <marth64@proxyid.net> Raw Captions With Time (RCWT) is a format native to ccextractor, a commonly used open source tool for processing 608/708 closed caption (CC) sources. It can be used to archive the original, raw CC bitstream and to produce a source file file for later CC processing or conversion. As a result, it also allows for interopability with ccextractor for processing CC data extracted via ffmpeg. The format is simple to parse and can be used to retain all lines and variants of CC. A free specification of RCWT can be found here: https://github.com/CCExtractor/ccextractor/blob/master/docs/BINARY_FILE_FORMAT.TXT This muxer implements the specification as of 01/05/2024, which has been stable and unchanged for 10 years as of this writing. This muxer will have some nuances from the way that ccextractor muxes RCWT. No compatibility issues when processing the output with ccextractor have been observed as a result of this so far, but mileage may vary and outputs will not be a bit-exact match. Specifically, the differences are: (1) This muxer will identify as "FF" as the writing program identifier, so as to be honest about the output's origin. (2) ffmpeg's MPEG-1/2, H264, HEVC, etc. decoders extract closed captioning data differently than ccextractor from embedded SEI/user data. For example, DVD captioning bytes will be translated to ATSC A53 format. This allows ffmpeg to handle 608/708 in a consistant way downstream. This is a lossless conversion and the meaningful data is retained. (3) This muxer will not alter the extracted data except to remove invalid packets in between valid CC blocks. On the other hand, ccextractor will by default remove mid-stream padding, and add padding at the end of the stream (in order to convey the end time of the source video).
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{
rcwt->cluster_pos = 0;
rcwt->cluster_pts = AV_NOPTS_VALUE;
}
static void rcwt_flush_cluster(AVFormatContext *avf)
{
RCWTContext *rcwt = avf->priv_data;
if (rcwt->cluster_pos > 0) {
libavformat: add RCWT closed caption muxex Signed-off-by: Marth64 <marth64@proxyid.net> Raw Captions With Time (RCWT) is a format native to ccextractor, a commonly used open source tool for processing 608/708 closed caption (CC) sources. It can be used to archive the original, raw CC bitstream and to produce a source file file for later CC processing or conversion. As a result, it also allows for interopability with ccextractor for processing CC data extracted via ffmpeg. The format is simple to parse and can be used to retain all lines and variants of CC. A free specification of RCWT can be found here: https://github.com/CCExtractor/ccextractor/blob/master/docs/BINARY_FILE_FORMAT.TXT This muxer implements the specification as of 01/05/2024, which has been stable and unchanged for 10 years as of this writing. This muxer will have some nuances from the way that ccextractor muxes RCWT. No compatibility issues when processing the output with ccextractor have been observed as a result of this so far, but mileage may vary and outputs will not be a bit-exact match. Specifically, the differences are: (1) This muxer will identify as "FF" as the writing program identifier, so as to be honest about the output's origin. (2) ffmpeg's MPEG-1/2, H264, HEVC, etc. decoders extract closed captioning data differently than ccextractor from embedded SEI/user data. For example, DVD captioning bytes will be translated to ATSC A53 format. This allows ffmpeg to handle 608/708 in a consistant way downstream. This is a lossless conversion and the meaningful data is retained. (3) This muxer will not alter the extracted data except to remove invalid packets in between valid CC blocks. On the other hand, ccextractor will by default remove mid-stream padding, and add padding at the end of the stream (in order to convey the end time of the source video).
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avio_wl64(avf->pb, rcwt->cluster_pts);
avio_wl16(avf->pb, rcwt->cluster_pos / RCWT_BLOCK_SIZE);
avio_write(avf->pb, rcwt->cluster_buf, rcwt->cluster_pos);
libavformat: add RCWT closed caption muxex Signed-off-by: Marth64 <marth64@proxyid.net> Raw Captions With Time (RCWT) is a format native to ccextractor, a commonly used open source tool for processing 608/708 closed caption (CC) sources. It can be used to archive the original, raw CC bitstream and to produce a source file file for later CC processing or conversion. As a result, it also allows for interopability with ccextractor for processing CC data extracted via ffmpeg. The format is simple to parse and can be used to retain all lines and variants of CC. A free specification of RCWT can be found here: https://github.com/CCExtractor/ccextractor/blob/master/docs/BINARY_FILE_FORMAT.TXT This muxer implements the specification as of 01/05/2024, which has been stable and unchanged for 10 years as of this writing. This muxer will have some nuances from the way that ccextractor muxes RCWT. No compatibility issues when processing the output with ccextractor have been observed as a result of this so far, but mileage may vary and outputs will not be a bit-exact match. Specifically, the differences are: (1) This muxer will identify as "FF" as the writing program identifier, so as to be honest about the output's origin. (2) ffmpeg's MPEG-1/2, H264, HEVC, etc. decoders extract closed captioning data differently than ccextractor from embedded SEI/user data. For example, DVD captioning bytes will be translated to ATSC A53 format. This allows ffmpeg to handle 608/708 in a consistant way downstream. This is a lossless conversion and the meaningful data is retained. (3) This muxer will not alter the extracted data except to remove invalid packets in between valid CC blocks. On the other hand, ccextractor will by default remove mid-stream padding, and add padding at the end of the stream (in order to convey the end time of the source video).
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}
rcwt_init_cluster(rcwt);
libavformat: add RCWT closed caption muxex Signed-off-by: Marth64 <marth64@proxyid.net> Raw Captions With Time (RCWT) is a format native to ccextractor, a commonly used open source tool for processing 608/708 closed caption (CC) sources. It can be used to archive the original, raw CC bitstream and to produce a source file file for later CC processing or conversion. As a result, it also allows for interopability with ccextractor for processing CC data extracted via ffmpeg. The format is simple to parse and can be used to retain all lines and variants of CC. A free specification of RCWT can be found here: https://github.com/CCExtractor/ccextractor/blob/master/docs/BINARY_FILE_FORMAT.TXT This muxer implements the specification as of 01/05/2024, which has been stable and unchanged for 10 years as of this writing. This muxer will have some nuances from the way that ccextractor muxes RCWT. No compatibility issues when processing the output with ccextractor have been observed as a result of this so far, but mileage may vary and outputs will not be a bit-exact match. Specifically, the differences are: (1) This muxer will identify as "FF" as the writing program identifier, so as to be honest about the output's origin. (2) ffmpeg's MPEG-1/2, H264, HEVC, etc. decoders extract closed captioning data differently than ccextractor from embedded SEI/user data. For example, DVD captioning bytes will be translated to ATSC A53 format. This allows ffmpeg to handle 608/708 in a consistant way downstream. This is a lossless conversion and the meaningful data is retained. (3) This muxer will not alter the extracted data except to remove invalid packets in between valid CC blocks. On the other hand, ccextractor will by default remove mid-stream padding, and add padding at the end of the stream (in order to convey the end time of the source video).
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}
static int rcwt_write_header(AVFormatContext *avf)
{
avpriv_set_pts_info(avf->streams[0], 64, 1, 1000);
/* magic number */
avio_wb16(avf->pb, 0xCCCC);
avio_w8(avf->pb, 0xED);
/* program version (identify as ffmpeg) */
avio_wb16(avf->pb, 0xFF00);
avio_w8(avf->pb, 0x60);
/* format version, only version 0.001 supported for now */
avio_wb16(avf->pb, 0x0001);
/* reserved */
avio_wb16(avf->pb, 0x000);
avio_w8(avf->pb, 0x00);
rcwt_init_cluster(avf->priv_data);
libavformat: add RCWT closed caption muxex Signed-off-by: Marth64 <marth64@proxyid.net> Raw Captions With Time (RCWT) is a format native to ccextractor, a commonly used open source tool for processing 608/708 closed caption (CC) sources. It can be used to archive the original, raw CC bitstream and to produce a source file file for later CC processing or conversion. As a result, it also allows for interopability with ccextractor for processing CC data extracted via ffmpeg. The format is simple to parse and can be used to retain all lines and variants of CC. A free specification of RCWT can be found here: https://github.com/CCExtractor/ccextractor/blob/master/docs/BINARY_FILE_FORMAT.TXT This muxer implements the specification as of 01/05/2024, which has been stable and unchanged for 10 years as of this writing. This muxer will have some nuances from the way that ccextractor muxes RCWT. No compatibility issues when processing the output with ccextractor have been observed as a result of this so far, but mileage may vary and outputs will not be a bit-exact match. Specifically, the differences are: (1) This muxer will identify as "FF" as the writing program identifier, so as to be honest about the output's origin. (2) ffmpeg's MPEG-1/2, H264, HEVC, etc. decoders extract closed captioning data differently than ccextractor from embedded SEI/user data. For example, DVD captioning bytes will be translated to ATSC A53 format. This allows ffmpeg to handle 608/708 in a consistant way downstream. This is a lossless conversion and the meaningful data is retained. (3) This muxer will not alter the extracted data except to remove invalid packets in between valid CC blocks. On the other hand, ccextractor will by default remove mid-stream padding, and add padding at the end of the stream (in order to convey the end time of the source video).
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return 0;
}
static int rcwt_write_packet(AVFormatContext *avf, AVPacket *pkt)
{
RCWTContext *rcwt = avf->priv_data;
if (pkt->size < RCWT_BLOCK_SIZE)
libavformat: add RCWT closed caption muxex Signed-off-by: Marth64 <marth64@proxyid.net> Raw Captions With Time (RCWT) is a format native to ccextractor, a commonly used open source tool for processing 608/708 closed caption (CC) sources. It can be used to archive the original, raw CC bitstream and to produce a source file file for later CC processing or conversion. As a result, it also allows for interopability with ccextractor for processing CC data extracted via ffmpeg. The format is simple to parse and can be used to retain all lines and variants of CC. A free specification of RCWT can be found here: https://github.com/CCExtractor/ccextractor/blob/master/docs/BINARY_FILE_FORMAT.TXT This muxer implements the specification as of 01/05/2024, which has been stable and unchanged for 10 years as of this writing. This muxer will have some nuances from the way that ccextractor muxes RCWT. No compatibility issues when processing the output with ccextractor have been observed as a result of this so far, but mileage may vary and outputs will not be a bit-exact match. Specifically, the differences are: (1) This muxer will identify as "FF" as the writing program identifier, so as to be honest about the output's origin. (2) ffmpeg's MPEG-1/2, H264, HEVC, etc. decoders extract closed captioning data differently than ccextractor from embedded SEI/user data. For example, DVD captioning bytes will be translated to ATSC A53 format. This allows ffmpeg to handle 608/708 in a consistant way downstream. This is a lossless conversion and the meaningful data is retained. (3) This muxer will not alter the extracted data except to remove invalid packets in between valid CC blocks. On the other hand, ccextractor will by default remove mid-stream padding, and add padding at the end of the stream (in order to convey the end time of the source video).
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return 0;
/* new PTS, new cluster */
if (pkt->pts != rcwt->cluster_pts) {
rcwt_flush_cluster(avf);
rcwt->cluster_pts = pkt->pts;
}
if (pkt->pts == AV_NOPTS_VALUE) {
av_log(avf, AV_LOG_WARNING, "Ignoring CC packet with no PTS\n");
return 0;
}
for (int i = 0; i <= pkt->size - RCWT_BLOCK_SIZE;) {
libavformat: add RCWT closed caption muxex Signed-off-by: Marth64 <marth64@proxyid.net> Raw Captions With Time (RCWT) is a format native to ccextractor, a commonly used open source tool for processing 608/708 closed caption (CC) sources. It can be used to archive the original, raw CC bitstream and to produce a source file file for later CC processing or conversion. As a result, it also allows for interopability with ccextractor for processing CC data extracted via ffmpeg. The format is simple to parse and can be used to retain all lines and variants of CC. A free specification of RCWT can be found here: https://github.com/CCExtractor/ccextractor/blob/master/docs/BINARY_FILE_FORMAT.TXT This muxer implements the specification as of 01/05/2024, which has been stable and unchanged for 10 years as of this writing. This muxer will have some nuances from the way that ccextractor muxes RCWT. No compatibility issues when processing the output with ccextractor have been observed as a result of this so far, but mileage may vary and outputs will not be a bit-exact match. Specifically, the differences are: (1) This muxer will identify as "FF" as the writing program identifier, so as to be honest about the output's origin. (2) ffmpeg's MPEG-1/2, H264, HEVC, etc. decoders extract closed captioning data differently than ccextractor from embedded SEI/user data. For example, DVD captioning bytes will be translated to ATSC A53 format. This allows ffmpeg to handle 608/708 in a consistant way downstream. This is a lossless conversion and the meaningful data is retained. (3) This muxer will not alter the extracted data except to remove invalid packets in between valid CC blocks. On the other hand, ccextractor will by default remove mid-stream padding, and add padding at the end of the stream (in order to convey the end time of the source video).
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uint8_t cc_valid;
uint8_t cc_type;
if (rcwt->cluster_pos == RCWT_CLUSTER_MAX_BLOCKS * RCWT_BLOCK_SIZE) {
libavformat: add RCWT closed caption muxex Signed-off-by: Marth64 <marth64@proxyid.net> Raw Captions With Time (RCWT) is a format native to ccextractor, a commonly used open source tool for processing 608/708 closed caption (CC) sources. It can be used to archive the original, raw CC bitstream and to produce a source file file for later CC processing or conversion. As a result, it also allows for interopability with ccextractor for processing CC data extracted via ffmpeg. The format is simple to parse and can be used to retain all lines and variants of CC. A free specification of RCWT can be found here: https://github.com/CCExtractor/ccextractor/blob/master/docs/BINARY_FILE_FORMAT.TXT This muxer implements the specification as of 01/05/2024, which has been stable and unchanged for 10 years as of this writing. This muxer will have some nuances from the way that ccextractor muxes RCWT. No compatibility issues when processing the output with ccextractor have been observed as a result of this so far, but mileage may vary and outputs will not be a bit-exact match. Specifically, the differences are: (1) This muxer will identify as "FF" as the writing program identifier, so as to be honest about the output's origin. (2) ffmpeg's MPEG-1/2, H264, HEVC, etc. decoders extract closed captioning data differently than ccextractor from embedded SEI/user data. For example, DVD captioning bytes will be translated to ATSC A53 format. This allows ffmpeg to handle 608/708 in a consistant way downstream. This is a lossless conversion and the meaningful data is retained. (3) This muxer will not alter the extracted data except to remove invalid packets in between valid CC blocks. On the other hand, ccextractor will by default remove mid-stream padding, and add padding at the end of the stream (in order to convey the end time of the source video).
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av_log(avf, AV_LOG_WARNING, "Starting new cluster due to size\n");
rcwt_flush_cluster(avf);
}
cc_valid = (pkt->data[i] & 0x04) >> 2;
cc_type = pkt->data[i] & 0x03;
if (!(cc_valid || cc_type == 3)) {
i++;
libavformat: add RCWT closed caption muxex Signed-off-by: Marth64 <marth64@proxyid.net> Raw Captions With Time (RCWT) is a format native to ccextractor, a commonly used open source tool for processing 608/708 closed caption (CC) sources. It can be used to archive the original, raw CC bitstream and to produce a source file file for later CC processing or conversion. As a result, it also allows for interopability with ccextractor for processing CC data extracted via ffmpeg. The format is simple to parse and can be used to retain all lines and variants of CC. A free specification of RCWT can be found here: https://github.com/CCExtractor/ccextractor/blob/master/docs/BINARY_FILE_FORMAT.TXT This muxer implements the specification as of 01/05/2024, which has been stable and unchanged for 10 years as of this writing. This muxer will have some nuances from the way that ccextractor muxes RCWT. No compatibility issues when processing the output with ccextractor have been observed as a result of this so far, but mileage may vary and outputs will not be a bit-exact match. Specifically, the differences are: (1) This muxer will identify as "FF" as the writing program identifier, so as to be honest about the output's origin. (2) ffmpeg's MPEG-1/2, H264, HEVC, etc. decoders extract closed captioning data differently than ccextractor from embedded SEI/user data. For example, DVD captioning bytes will be translated to ATSC A53 format. This allows ffmpeg to handle 608/708 in a consistant way downstream. This is a lossless conversion and the meaningful data is retained. (3) This muxer will not alter the extracted data except to remove invalid packets in between valid CC blocks. On the other hand, ccextractor will by default remove mid-stream padding, and add padding at the end of the stream (in order to convey the end time of the source video).
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continue;
}
memcpy(&rcwt->cluster_buf[rcwt->cluster_pos], &pkt->data[i], 3);
rcwt->cluster_pos += 3;
i += 3;
libavformat: add RCWT closed caption muxex Signed-off-by: Marth64 <marth64@proxyid.net> Raw Captions With Time (RCWT) is a format native to ccextractor, a commonly used open source tool for processing 608/708 closed caption (CC) sources. It can be used to archive the original, raw CC bitstream and to produce a source file file for later CC processing or conversion. As a result, it also allows for interopability with ccextractor for processing CC data extracted via ffmpeg. The format is simple to parse and can be used to retain all lines and variants of CC. A free specification of RCWT can be found here: https://github.com/CCExtractor/ccextractor/blob/master/docs/BINARY_FILE_FORMAT.TXT This muxer implements the specification as of 01/05/2024, which has been stable and unchanged for 10 years as of this writing. This muxer will have some nuances from the way that ccextractor muxes RCWT. No compatibility issues when processing the output with ccextractor have been observed as a result of this so far, but mileage may vary and outputs will not be a bit-exact match. Specifically, the differences are: (1) This muxer will identify as "FF" as the writing program identifier, so as to be honest about the output's origin. (2) ffmpeg's MPEG-1/2, H264, HEVC, etc. decoders extract closed captioning data differently than ccextractor from embedded SEI/user data. For example, DVD captioning bytes will be translated to ATSC A53 format. This allows ffmpeg to handle 608/708 in a consistant way downstream. This is a lossless conversion and the meaningful data is retained. (3) This muxer will not alter the extracted data except to remove invalid packets in between valid CC blocks. On the other hand, ccextractor will by default remove mid-stream padding, and add padding at the end of the stream (in order to convey the end time of the source video).
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}
return 0;
}
static int rcwt_write_trailer(AVFormatContext *avf)
{
rcwt_flush_cluster(avf);
return 0;
}
const FFOutputFormat ff_rcwt_muxer = {
.p.name = "rcwt",
.p.long_name = NULL_IF_CONFIG_SMALL("RCWT (Raw Captions With Time)"),
libavformat: add RCWT closed caption muxex Signed-off-by: Marth64 <marth64@proxyid.net> Raw Captions With Time (RCWT) is a format native to ccextractor, a commonly used open source tool for processing 608/708 closed caption (CC) sources. It can be used to archive the original, raw CC bitstream and to produce a source file file for later CC processing or conversion. As a result, it also allows for interopability with ccextractor for processing CC data extracted via ffmpeg. The format is simple to parse and can be used to retain all lines and variants of CC. A free specification of RCWT can be found here: https://github.com/CCExtractor/ccextractor/blob/master/docs/BINARY_FILE_FORMAT.TXT This muxer implements the specification as of 01/05/2024, which has been stable and unchanged for 10 years as of this writing. This muxer will have some nuances from the way that ccextractor muxes RCWT. No compatibility issues when processing the output with ccextractor have been observed as a result of this so far, but mileage may vary and outputs will not be a bit-exact match. Specifically, the differences are: (1) This muxer will identify as "FF" as the writing program identifier, so as to be honest about the output's origin. (2) ffmpeg's MPEG-1/2, H264, HEVC, etc. decoders extract closed captioning data differently than ccextractor from embedded SEI/user data. For example, DVD captioning bytes will be translated to ATSC A53 format. This allows ffmpeg to handle 608/708 in a consistant way downstream. This is a lossless conversion and the meaningful data is retained. (3) This muxer will not alter the extracted data except to remove invalid packets in between valid CC blocks. On the other hand, ccextractor will by default remove mid-stream padding, and add padding at the end of the stream (in order to convey the end time of the source video).
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.p.flags = AVFMT_GLOBALHEADER | AVFMT_VARIABLE_FPS | AVFMT_TS_NONSTRICT,
.p.video_codec = AV_CODEC_ID_NONE,
.p.audio_codec = AV_CODEC_ID_NONE,
libavformat: add RCWT closed caption muxex Signed-off-by: Marth64 <marth64@proxyid.net> Raw Captions With Time (RCWT) is a format native to ccextractor, a commonly used open source tool for processing 608/708 closed caption (CC) sources. It can be used to archive the original, raw CC bitstream and to produce a source file file for later CC processing or conversion. As a result, it also allows for interopability with ccextractor for processing CC data extracted via ffmpeg. The format is simple to parse and can be used to retain all lines and variants of CC. A free specification of RCWT can be found here: https://github.com/CCExtractor/ccextractor/blob/master/docs/BINARY_FILE_FORMAT.TXT This muxer implements the specification as of 01/05/2024, which has been stable and unchanged for 10 years as of this writing. This muxer will have some nuances from the way that ccextractor muxes RCWT. No compatibility issues when processing the output with ccextractor have been observed as a result of this so far, but mileage may vary and outputs will not be a bit-exact match. Specifically, the differences are: (1) This muxer will identify as "FF" as the writing program identifier, so as to be honest about the output's origin. (2) ffmpeg's MPEG-1/2, H264, HEVC, etc. decoders extract closed captioning data differently than ccextractor from embedded SEI/user data. For example, DVD captioning bytes will be translated to ATSC A53 format. This allows ffmpeg to handle 608/708 in a consistant way downstream. This is a lossless conversion and the meaningful data is retained. (3) This muxer will not alter the extracted data except to remove invalid packets in between valid CC blocks. On the other hand, ccextractor will by default remove mid-stream padding, and add padding at the end of the stream (in order to convey the end time of the source video).
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.p.subtitle_codec = AV_CODEC_ID_EIA_608,
.flags_internal = FF_OFMT_FLAG_MAX_ONE_OF_EACH |
FF_OFMT_FLAG_ONLY_DEFAULT_CODECS,
libavformat: add RCWT closed caption muxex Signed-off-by: Marth64 <marth64@proxyid.net> Raw Captions With Time (RCWT) is a format native to ccextractor, a commonly used open source tool for processing 608/708 closed caption (CC) sources. It can be used to archive the original, raw CC bitstream and to produce a source file file for later CC processing or conversion. As a result, it also allows for interopability with ccextractor for processing CC data extracted via ffmpeg. The format is simple to parse and can be used to retain all lines and variants of CC. A free specification of RCWT can be found here: https://github.com/CCExtractor/ccextractor/blob/master/docs/BINARY_FILE_FORMAT.TXT This muxer implements the specification as of 01/05/2024, which has been stable and unchanged for 10 years as of this writing. This muxer will have some nuances from the way that ccextractor muxes RCWT. No compatibility issues when processing the output with ccextractor have been observed as a result of this so far, but mileage may vary and outputs will not be a bit-exact match. Specifically, the differences are: (1) This muxer will identify as "FF" as the writing program identifier, so as to be honest about the output's origin. (2) ffmpeg's MPEG-1/2, H264, HEVC, etc. decoders extract closed captioning data differently than ccextractor from embedded SEI/user data. For example, DVD captioning bytes will be translated to ATSC A53 format. This allows ffmpeg to handle 608/708 in a consistant way downstream. This is a lossless conversion and the meaningful data is retained. (3) This muxer will not alter the extracted data except to remove invalid packets in between valid CC blocks. On the other hand, ccextractor will by default remove mid-stream padding, and add padding at the end of the stream (in order to convey the end time of the source video).
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.priv_data_size = sizeof(RCWTContext),
.write_header = rcwt_write_header,
.write_packet = rcwt_write_packet,
.write_trailer = rcwt_write_trailer
};