[FFmpeg-devel] [PATCH 3/3] TTML encoder and muxer
Andreas Rheinhardt
andreas.rheinhardt at gmail.com
Mon Dec 7 16:03:10 EET 2020
Andreas Rheinhardt:
> Jan Ekström:
>> From: Jan Ekström <jan.ekstrom at 24i.com>
>>
>> Enables encoding of other subtitle formats into TTML and writing
>> them out as such documents.
>>
>> Signed-off-by: Jan Ekström <jan.ekstrom at 24i.com>
>> ---
>> Changelog | 1 +
>> doc/general_contents.texi | 1 +
>> libavcodec/Makefile | 1 +
>> libavcodec/allcodecs.c | 1 +
>> libavcodec/ttmlenc.c | 154 +++++++++++++++++++++++++++++++++++++
>> libavcodec/version.h | 2 +-
>> libavformat/Makefile | 1 +
>> libavformat/allformats.c | 1 +
>> libavformat/ttmlenc.c | 123 +++++++++++++++++++++++++++++
>> libavformat/version.h | 2 +-
>> tests/fate/subtitles.mak | 3 +
>> tests/ref/fate/sub-ttmlenc | 122 +++++++++++++++++++++++++++++
>> 12 files changed, 410 insertions(+), 2 deletions(-)
>> create mode 100644 libavcodec/ttmlenc.c
>> create mode 100644 libavformat/ttmlenc.c
>> create mode 100644 tests/ref/fate/sub-ttmlenc
>>
>> diff --git a/Changelog b/Changelog
>> index ebb1727875..71476eb366 100644
>> --- a/Changelog
>> +++ b/Changelog
>> @@ -48,6 +48,7 @@ version <next>:
>> - speechnorm filter
>> - SpeedHQ encoder
>> - asupercut filter
>> +- TTML subtitle encoder and muxer
>>
>>
>> version 4.3:
>> diff --git a/doc/general_contents.texi b/doc/general_contents.texi
>> index 1be6f9b683..dca183e9ca 100644
>> --- a/doc/general_contents.texi
>> +++ b/doc/general_contents.texi
>> @@ -1332,6 +1332,7 @@ performance on systems without hardware floating point support).
>> @item SubViewer v1 @tab @tab X @tab @tab X
>> @item SubViewer @tab @tab X @tab @tab X
>> @item TED Talks captions @tab @tab X @tab @tab X
>> + at item TTML @tab X @tab @tab X @tab
>> @item VobSub (IDX+SUB) @tab @tab X @tab @tab X
>> @item VPlayer @tab @tab X @tab @tab X
>> @item WebVTT @tab X @tab X @tab X @tab X
>> diff --git a/libavcodec/Makefile b/libavcodec/Makefile
>> index a6435c9e85..9d2b62a263 100644
>> --- a/libavcodec/Makefile
>> +++ b/libavcodec/Makefile
>> @@ -665,6 +665,7 @@ OBJS-$(CONFIG_TSCC_DECODER) += tscc.o msrledec.o
>> OBJS-$(CONFIG_TSCC2_DECODER) += tscc2.o
>> OBJS-$(CONFIG_TTA_DECODER) += tta.o ttadata.o ttadsp.o
>> OBJS-$(CONFIG_TTA_ENCODER) += ttaenc.o ttaencdsp.o ttadata.o
>> +OBJS-$(CONFIG_TTML_ENCODER) += ttmlenc.o ass_split.o
>> OBJS-$(CONFIG_TWINVQ_DECODER) += twinvqdec.o twinvq.o
>> OBJS-$(CONFIG_TXD_DECODER) += txd.o
>> OBJS-$(CONFIG_ULTI_DECODER) += ulti.o
>> diff --git a/libavcodec/allcodecs.c b/libavcodec/allcodecs.c
>> index 774d5670bf..b12538905b 100644
>> --- a/libavcodec/allcodecs.c
>> +++ b/libavcodec/allcodecs.c
>> @@ -685,6 +685,7 @@ extern AVCodec ff_subviewer_decoder;
>> extern AVCodec ff_subviewer1_decoder;
>> extern AVCodec ff_text_encoder;
>> extern AVCodec ff_text_decoder;
>> +extern AVCodec ff_ttml_encoder;
>> extern AVCodec ff_vplayer_decoder;
>> extern AVCodec ff_webvtt_encoder;
>> extern AVCodec ff_webvtt_decoder;
>> diff --git a/libavcodec/ttmlenc.c b/libavcodec/ttmlenc.c
>> new file mode 100644
>> index 0000000000..7eb89e73f4
>> --- /dev/null
>> +++ b/libavcodec/ttmlenc.c
>> @@ -0,0 +1,154 @@
>> +/*
>> + * TTML subtitle encoder
>> + * Copyright (c) 2020 24i
>> + *
>> + * 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
>> + */
>> +
>> +/**
>> + * @file
>> + * TTML subtitle encoder
>> + * @see https://www.w3.org/TR/ttml1/
>> + * @see https://www.w3.org/TR/ttml2/
>> + * @see https://www.w3.org/TR/ttml-imsc/rec
>> + */
>> +
>> +#include "avcodec.h"
>> +#include "libavutil/avstring.h"
>> +#include "libavutil/bprint.h"
>> +#include "ass_split.h"
>> +#include "ass.h"
>> +
>> +typedef struct {
>> + AVCodecContext *avctx;
>> + ASSSplitContext *ass_ctx;
>> + AVBPrint buffer;
>> +} TTMLContext;
>> +
>> +static void ttml_text_cb(void *priv, const char *text, int len)
>> +{
>> + TTMLContext *s = priv;
>> + AVBPrint cur_line = { 0 };
>> + AVBPrint *buffer = &s->buffer;
>> +
>> + av_bprint_init(&cur_line, len, AV_BPRINT_SIZE_UNLIMITED);
>> +
>> + av_bprint_append_data(&cur_line, text, len);
>> + if (!av_bprint_is_complete(&cur_line)) {
>> + av_log(s->avctx, AV_LOG_ERROR,
>> + "Failed to move the current subtitle dialog to AVBPrint!\n");
>> + av_bprint_finalize(&cur_line, NULL);
>> + return;
>> + }
>> +
>> +
>> + av_bprint_escape(buffer, cur_line.str, NULL, AV_ESCAPE_MODE_XML, 0);
>> +
>> + av_bprint_finalize(&cur_line, NULL);
>> +}
>> +
>> +static void ttml_new_line_cb(void *priv, int forced)
>> +{
>> + TTMLContext *s = priv;
>> +
>> + av_bprintf(&s->buffer, "<br/>");
>> +}
>> +
>> +static const ASSCodesCallbacks ttml_callbacks = {
>> + .text = ttml_text_cb,
>> + .new_line = ttml_new_line_cb,
>> +};
>> +
>> +static int ttml_encode_frame(AVCodecContext *avctx, uint8_t *buf,
>> + int bufsize, const AVSubtitle *sub)
>> +{
>> + TTMLContext *s = avctx->priv_data;
>> + ASSDialog *dialog;
>> + int i;
>> +
>> + av_bprint_clear(&s->buffer);
>> +
>> + for (i=0; i<sub->num_rects; i++) {
>> + const char *ass = sub->rects[i]->ass;
>> +
>> + if (sub->rects[i]->type != SUBTITLE_ASS) {
>> + av_log(avctx, AV_LOG_ERROR, "Only SUBTITLE_ASS type supported.\n");
>> + return AVERROR(ENOSYS);
>> + }
>> +
>> +#if FF_API_ASS_TIMING
>> + if (!strncmp(ass, "Dialogue: ", 10)) {
>> + int num;
>> + dialog = ff_ass_split_dialog(s->ass_ctx, ass, 0, &num);
>> +
>> + for (; dialog && num--; dialog++) {
>> + ff_ass_split_override_codes(&ttml_callbacks, s, dialog->text);
>> + }
>> + } else {
>> +#endif
>> + dialog = ff_ass_split_dialog2(s->ass_ctx, ass);
>> + if (!dialog)
>> + return AVERROR(ENOMEM);
>> +
>> + ff_ass_split_override_codes(&ttml_callbacks, s, dialog->text);
>> + ff_ass_free_dialog(&dialog);
>> +#if FF_API_ASS_TIMING
>> + }
>> +#endif
>> + }
>> +
>> + if (!av_bprint_is_complete(&s->buffer))
>> + return AVERROR(ENOMEM);
>> + if (!s->buffer.len)
>> + return 0;
>> +
>> + if (s->buffer.len > bufsize) {
>> + av_log(avctx, AV_LOG_ERROR, "Buffer too small for ASS event.\n");
>> + return -1;
>
> Not AVERROR_BUFFER_TOO_SMALL?
>
>> + }
>> + memcpy(buf, s->buffer.str, s->buffer.len);
>
> You are not copying the terminating NUL; and you also don't account for
> it in the above check. Is this intended?
>
The srt encoder does it like you, the ass encoder is careful only to
output a NUL terminated string (with the NUL not accounted for in the
size); no documentation exists for avcodec_encode_subtitle(). ffmpeg.c
uses the size of the allocated (not-zeroed) buffer as bufsize; it also
does not add any padding at all (but it's buffer is huge (1MiB)).
>> +
>> + return s->buffer.len;
>> +}
>> +
>> +static av_cold int ttml_encode_close(AVCodecContext *avctx)
>> +{
>> + TTMLContext *s = avctx->priv_data;
>> + ff_ass_split_free(s->ass_ctx);
>> + av_bprint_finalize(&s->buffer, NULL);
>> + return 0;
>> +}
>> +
>> +static av_cold int ttml_encode_init(AVCodecContext *avctx)
>> +{
>> + TTMLContext *s = avctx->priv_data;
>> + s->avctx = avctx;
>> + s->ass_ctx = ff_ass_split(avctx->subtitle_header);
>> + av_bprint_init(&s->buffer, 0, AV_BPRINT_SIZE_UNLIMITED);
>> + return s->ass_ctx ? 0 : AVERROR_INVALIDDATA;
>> +}
>> +
>> +AVCodec ff_ttml_encoder = {
>> + .name = "ttml",
>> + .long_name = NULL_IF_CONFIG_SMALL("TTML subtitle"),
>> + .type = AVMEDIA_TYPE_SUBTITLE,
>> + .id = AV_CODEC_ID_TTML,
>> + .priv_data_size = sizeof(TTMLContext),
>> + .init = ttml_encode_init,
>> + .encode_sub = ttml_encode_frame,
>> + .close = ttml_encode_close,
>> +};
>> diff --git a/libavcodec/version.h b/libavcodec/version.h
>> index e4b81da7cb..4ee221b7f2 100644
>> --- a/libavcodec/version.h
>> +++ b/libavcodec/version.h
>> @@ -28,7 +28,7 @@
>> #include "libavutil/version.h"
>>
>> #define LIBAVCODEC_VERSION_MAJOR 58
>> -#define LIBAVCODEC_VERSION_MINOR 114
>> +#define LIBAVCODEC_VERSION_MINOR 115
>> #define LIBAVCODEC_VERSION_MICRO 100
>>
>> #define LIBAVCODEC_VERSION_INT AV_VERSION_INT(LIBAVCODEC_VERSION_MAJOR, \
>> diff --git a/libavformat/Makefile b/libavformat/Makefile
>> index be5a482b01..cbf9de0fc6 100644
>> --- a/libavformat/Makefile
>> +++ b/libavformat/Makefile
>> @@ -542,6 +542,7 @@ OBJS-$(CONFIG_TRUEHD_DEMUXER) += rawdec.o mlpdec.o
>> OBJS-$(CONFIG_TRUEHD_MUXER) += rawenc.o
>> OBJS-$(CONFIG_TTA_DEMUXER) += tta.o apetag.o img2.o
>> OBJS-$(CONFIG_TTA_MUXER) += ttaenc.o apetag.o img2.o
>> +OBJS-$(CONFIG_TTML_MUXER) += ttmlenc.o
>> OBJS-$(CONFIG_TTY_DEMUXER) += tty.o sauce.o
>> OBJS-$(CONFIG_TY_DEMUXER) += ty.o
>> OBJS-$(CONFIG_TXD_DEMUXER) += txd.o
>> diff --git a/libavformat/allformats.c b/libavformat/allformats.c
>> index 53e5374255..ce0ff0e2d3 100644
>> --- a/libavformat/allformats.c
>> +++ b/libavformat/allformats.c
>> @@ -441,6 +441,7 @@ extern AVInputFormat ff_truehd_demuxer;
>> extern AVOutputFormat ff_truehd_muxer;
>> extern AVInputFormat ff_tta_demuxer;
>> extern AVOutputFormat ff_tta_muxer;
>> +extern AVOutputFormat ff_ttml_muxer;
>> extern AVInputFormat ff_txd_demuxer;
>> extern AVInputFormat ff_tty_demuxer;
>> extern AVInputFormat ff_ty_demuxer;
>> diff --git a/libavformat/ttmlenc.c b/libavformat/ttmlenc.c
>> new file mode 100644
>> index 0000000000..6ba248ee30
>> --- /dev/null
>> +++ b/libavformat/ttmlenc.c
>> @@ -0,0 +1,123 @@
>> +/*
>> + * TTML subtitle muxer
>> + * Copyright (c) 2020 24i
>> + *
>> + * 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
>> + */
>> +
>> +/**
>> + * @file
>> + * TTML subtitle muxer
>> + * @see https://www.w3.org/TR/ttml1/
>> + * @see https://www.w3.org/TR/ttml2/
>> + * @see https://www.w3.org/TR/ttml-imsc/rec
>> + */
>> +
>> +#include "avformat.h"
>> +#include "internal.h"
>> +
>> +static const char ttml_header_text[] =
>> +"<?xml version=\"1.0\" encoding=\"utf-8\"?>\n"
>> +"<tt\n"
>> +" xmlns=\"http://www.w3.org/ns/ttml\"\n"
>> +" xmlns:ttm=\"http://www.w3.org/ns/ttml#metadata\"\n"
>> +" xmlns:tts=\"http://www.w3.org/ns/ttml#styling\"\n"
>> +" xml:lang=\"%s\">\n"
>> +" <body>\n"
>> +" <div>\n";
>> +
>> +static const char ttml_footer_text[] =
>> +" </div>\n"
>> +" </body>\n"
>> +"</tt>\n";
>> +
>> +static void ttml_write_time(AVIOContext *pb, const char tag[],
>> + int64_t millisec)
>> +{
>> + int64_t sec, min, hour;
>> + sec = millisec / 1000;
>> + millisec -= 1000 * sec;
>> + min = sec / 60;
>> + sec -= 60 * min;
>> + hour = min / 60;
>> + min -= 60 * hour;
>> +
>> + avio_printf(pb, "%s=\"%02"PRId64":%02"PRId64":%02"PRId64".%03"PRId64"\"",
>> + tag, hour, min, sec, millisec);
>> +}
>> +
>> +static int ttml_write_header(AVFormatContext *ctx)
>> +{
>> + if (ctx->nb_streams != 1 ||
>> + ctx->streams[0]->codecpar->codec_id != AV_CODEC_ID_TTML) {
>> + av_log(ctx, AV_LOG_ERROR, "Exactly one TTML stream is required!\n");
>> + return AVERROR(EINVAL);
>> + }
>> +
>> + {
>> + AVStream *s = ctx->streams[0];
>
> The typical naming in libavformat uses s for AVFormatContext and st for
> stream. (I already wanted to complain that the first argument of
> avpriv_set_pts_info() is wrong.)
>
>> + AVIOContext *pb = ctx->pb;
>> +
>> + AVDictionaryEntry *lang = av_dict_get(s->metadata, "language", NULL, 0);
>> + const char *printed_lang = (lang && lang->value) ? lang->value : "";
>> +
>> + avpriv_set_pts_info(s, 64, 1, 1000);
>> +
>> + avio_printf(pb, ttml_header_text, printed_lang);
>> +
>
> "xml:lang=" is mandatory even without a language?
>
>> + avio_flush(pb);
>> + }
>> +
>> + return 0;
>> +}
>> +
>> +static int ttml_write_packet(AVFormatContext *ctx, AVPacket *pkt)
>> +{
>> + AVIOContext *pb = ctx->pb;
>> +
>> + avio_printf(pb, " <p\n");
>> + ttml_write_time(pb, " begin", pkt->pts);
>> + avio_printf(pb, "\n");
>
> How about avio_w88(pb, '\n')?
>
>> + ttml_write_time(pb, " end", pkt->pts + pkt->duration);
>> + avio_printf(pb, ">");
>> + avio_write(pb, pkt->data, pkt->size);
>> + avio_printf(pb, "</p>\n");
>> +
>> + return 0;
>> +}
>> +
>> +static int ttml_write_trailer(AVFormatContext *ctx)
>> +{
>> + AVIOContext *pb = ctx->pb;
>> +
>> + avio_printf(pb, ttml_footer_text);
>> + avio_flush(pb);
>> +
>> + return 0;
>> +}
>> +
>> +AVOutputFormat ff_ttml_muxer = {
>> + .name = "ttml",
>> + .long_name = NULL_IF_CONFIG_SMALL("TTML subtitle"),
>> + .extensions = "ttml",
>> + .mime_type = "text/ttml",
>> + .flags = AVFMT_GLOBALHEADER | AVFMT_VARIABLE_FPS | AVFMT_TS_NONSTRICT,
>> + .subtitle_codec = AV_CODEC_ID_TTML,
>> + .write_header = ttml_write_header,
>> + .write_packet = ttml_write_packet,
>> + .write_trailer = ttml_write_trailer,
>> +};
>> diff --git a/libavformat/version.h b/libavformat/version.h
>> index ddcca9ae50..b43193bcb1 100644
>> --- a/libavformat/version.h
>> +++ b/libavformat/version.h
>> @@ -32,7 +32,7 @@
>> // Major bumping may affect Ticket5467, 5421, 5451(compatibility with Chromium)
>> // Also please add any ticket numbers that you believe might be affected here
>> #define LIBAVFORMAT_VERSION_MAJOR 58
>> -#define LIBAVFORMAT_VERSION_MINOR 64
>> +#define LIBAVFORMAT_VERSION_MINOR 65
>> #define LIBAVFORMAT_VERSION_MICRO 100
>>
>> #define LIBAVFORMAT_VERSION_INT AV_VERSION_INT(LIBAVFORMAT_VERSION_MAJOR, \
>> diff --git a/tests/fate/subtitles.mak b/tests/fate/subtitles.mak
>> index 6323d0f93d..ee65afe35b 100644
>> --- a/tests/fate/subtitles.mak
>> +++ b/tests/fate/subtitles.mak
>> @@ -106,6 +106,9 @@ fate-sub-scc: CMD = fmtstdout ass -ss 57 -i $(TARGET_SAMPLES)/sub/witch.scc
>> FATE_SUBTITLES-$(call ALLYES, MPEGTS_DEMUXER DVBSUB_DECODER DVBSUB_ENCODER) += fate-sub-dvb
>> fate-sub-dvb: CMD = framecrc -i $(TARGET_SAMPLES)/sub/dvbsubtest_filter.ts -map s:0 -c dvbsub
>>
>> +FATE_SUBTITLES-$(call ALLYES, FILE_PROTOCOL PIPE_PROTOCOL SRT_DEMUXER SUBRIP_DECODER TTML_ENCODER TTML_MUXER) += fate-sub-ttmlenc
>> +fate-sub-ttmlenc: CMD = fmtstdout ttml -i $(TARGET_SAMPLES)/sub/SubRip_capability_tester.srt
>> +
>> FATE_SUBTITLES-$(call ENCMUX, ASS, ASS) += $(FATE_SUBTITLES_ASS-yes)
>> FATE_SUBTITLES += $(FATE_SUBTITLES-yes)
>>
>> diff --git a/tests/ref/fate/sub-ttmlenc b/tests/ref/fate/sub-ttmlenc
>> new file mode 100644
>> index 0000000000..624f37d092
>> --- /dev/null
>> +++ b/tests/ref/fate/sub-ttmlenc
>> @@ -0,0 +1,122 @@
>> +<?xml version="1.0" encoding="utf-8"?>
>> +<tt
>> + xmlns="http://www.w3.org/ns/ttml"
>> + xmlns:ttm="http://www.w3.org/ns/ttml#metadata"
>> + xmlns:tts="http://www.w3.org/ns/ttml#styling"
>> + xml:lang="">
>> + <body>
>> + <div>
>> + <p
>> + begin="00:00:00.000"
>> + end="00:00:00.000">Don't show this text it may be used to insert hidden data</p>
>> + <p
>> + begin="00:00:01.500"
>> + end="00:00:04.500">SubRip subtitles capability tester 1.3o by ale5000<br/>Use VLC 1.1 or higher as reference for most things and MPC Home Cinema for others<br/>This text should be blue<br/>This text should be red<br/>This text should be black<br/>If you see this with the normal font, the player don't (fully) support font face</p>
>> + <p
>> + begin="00:00:04.500"
>> + end="00:00:04.500">Hidden</p>
>> + <p
>> + begin="00:00:04.501"
>> + end="00:00:07.500">This text should be small<br/>This text should be normal<br/>This text should be big</p>
>> + <p
>> + begin="00:00:07.501"
>> + end="00:00:11.500">This should be an E with an accent: È<br/>日本語<br/>This text should be bold, italics and underline<br/>This text should be small and green<br/>This text should be small and red<br/>This text should be big and brown</p>
>> + <p
>> + begin="00:00:11.501"
>> + end="00:00:14.500">This line should be bold<br/>This line should be italics<br/>This line should be underline<br/>This line should be strikethrough<br/>Both lines<br/>should be underline</p>
>> + <p
>> + begin="00:00:14.501"
>> + end="00:00:17.500">><br/>It would be a good thing to<br/>hide invalid html tags that are closed and show the text in them<br/>but show un-closed invalid html tags<br/>Show not opened tags<br/><</p>
>> + <p
>> + begin="00:00:17.501"
>> + end="00:00:20.500">and also<br/>hide invalid html tags with parameters that are closed and show the text in them<br/>but show un-closed invalid html tags<br/>This text should be showed underlined without problems also: 2<3,5>1,4<6<br/>This shouldn't be underlined</p>
>> + <p
>> + begin="00:00:20.501"
>> + end="00:00:21.500">This text should be in the normal position...</p>
>> + <p
>> + begin="00:00:21.501"
>> + end="00:00:22.500">This text should NOT be in the normal position</p>
>> + <p
>> + begin="00:00:22.501"
>> + end="00:00:24.500">Implementation is the same of the ASS tag<br/>This text should be at the<br/>top and horizontally centered</p>
>> + <p
>> + begin="00:00:22.501"
>> + end="00:00:24.500">This text should be at the<br/>middle and horizontally centered</p>
>> + <p
>> + begin="00:00:22.501"
>> + end="00:00:24.500">This text should be at the<br/>bottom and horizontally centered</p>
>> + <p
>> + begin="00:00:24.501"
>> + end="00:00:26.500">This text should be at the<br/>top and horizontally at the left</p>
>> + <p
>> + begin="00:00:24.501"
>> + end="00:00:26.500">This text should be at the<br/>middle and horizontally at the left<br/>(The second position must be ignored)</p>
>> + <p
>> + begin="00:00:24.501"
>> + end="00:00:26.500">This text should be at the<br/>bottom and horizontally at the left</p>
>> + <p
>> + begin="00:00:26.501"
>> + end="00:00:28.500">This text should be at the<br/>top and horizontally at the right</p>
>> + <p
>> + begin="00:00:26.501"
>> + end="00:00:28.500">This text should be at the<br/>middle and horizontally at the right</p>
>> + <p
>> + begin="00:00:26.501"
>> + end="00:00:28.500">This text should be at the<br/>bottom and horizontally at the right</p>
>> + <p
>> + begin="00:00:28.501"
>> + end="00:00:31.500">This could be the most difficult thing to implement</p>
>> + <p
>> + begin="00:00:31.501"
>> + end="00:00:50.500">First text</p>
>> + <p
>> + begin="00:00:33.500"
>> + end="00:00:35.500">Second, it shouldn't overlap first</p>
>> + <p
>> + begin="00:00:35.501"
>> + end="00:00:37.500">Third, it should replace second</p>
>> + <p
>> + begin="00:00:36.501"
>> + end="00:00:50.500">Fourth, it shouldn't overlap first and third</p>
>> + <p
>> + begin="00:00:40.501"
>> + end="00:00:45.500">Fifth, it should replace third</p>
>> + <p
>> + begin="00:00:45.501"
>> + end="00:00:50.500">Sixth, it shouldn't be<br/>showed overlapped</p>
>> + <p
>> + begin="00:00:50.501"
>> + end="00:00:52.500">TEXT 1 (bottom)</p>
>> + <p
>> + begin="00:00:50.501"
>> + end="00:00:52.500">text 2</p>
>> + <p
>> + begin="00:00:52.501"
>> + end="00:00:54.500">Hide these tags:<br/>also hide these tags:<br/>but show this: {normal text}</p>
>> + <p
>> + begin="00:00:54.501"
>> + end="00:01:00.500"><br/>\ N is a forced line break<br/>\ h is a hard space<br/>Normal spaces at the start and at the end of the line are trimmed while hard spaces are not trimmed.<br/>The\hline\hwill\hnever\hbreak\hautomatically\hright\hbefore\hor\hafter\ha\hhard\hspace.\h:-D</p>
>> + <p
>> + begin="00:00:54.501"
>> + end="00:00:56.500"><br/>\h\h\h\h\hA (05 hard spaces followed by a letter)<br/>A (Normal spaces followed by a letter)<br/>A (No hard spaces followed by a letter)</p>
>> + <p
>> + begin="00:00:56.501"
>> + end="00:00:58.500">\h\h\h\h\hA (05 hard spaces followed by a letter)<br/>A (Normal spaces followed by a letter)<br/>A (No hard spaces followed by a letter)<br/>Show this: \TEST and this: \-)</p>
>> + <p
>> + begin="00:00:58.501"
>> + end="00:01:00.500"><br/>A letter followed by 05 hard spaces: A\h\h\h\h\h<br/>A letter followed by normal spaces: A<br/>A letter followed by no hard spaces: A<br/>05 hard spaces between letters: A\h\h\h\h\hA<br/>5 normal spaces between letters: A A<br/><br/>^--Forced line break</p>
>> + <p
>> + begin="00:01:00.501"
>> + end="00:01:02.500">Both line should be strikethrough,<br/>yes.<br/>Correctly closed tags<br/>should be hidden.</p>
>> + <p
>> + begin="00:01:02.501"
>> + end="00:01:04.500">It shouldn't be strikethrough,<br/>not opened tag showed as text.<br/>Not opened tag showed as text.</p>
>> + <p
>> + begin="00:01:04.501"
>> + end="00:01:06.500">Three lines should be strikethrough,<br/>yes.<br/>Not closed tags showed as text</p>
>> + <p
>> + begin="00:01:06.501"
>> + end="00:01:08.500">Both line should be strikethrough but<br/>the wrong closing tag should be showed</p>
>> + </div>
>> + </body>
>> +</tt>
>>
>
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