On Mon, Dec 7, 2020 at 3:56 PM Andreas Rheinhardt
<andreas.rheinha...@gmail.com> wrote:
>
> Jan Ekström:
> > From: Jan Ekström <jan.ekst...@24i.com>
> >
> > Enables encoding of other subtitle formats into TTML and writing
> > them out as such documents.
> >
> > Signed-off-by: Jan Ekström <jan.ekst...@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
> > +@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?
>
Yup. I just had noticed that as well as I started adding what was
recommended on IRC. Also it says "ASS event" even though it's a TTML
paragraph at this point, so I will also fix that.
> > + }
> > + 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?
I think I followed either webvttenc or srtenc in this. Technically I
/think/ under certain circuimstances AVBprint does lead to a trailing
nul to be there if av_bprint_is_complete returns true, but I cannot
vouch for it - would have to check the implementation and especially
av_bprint_append_data.
>
> > +
> > + 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.)
>
I agree. Apparently this came from the times when this code was based
on webvttenc, where "s" was utilized for the AVStream in
webvtt_write_header . And then when you're trying to go back and
attempt to bring things up to a level you often miss these things.
> > + 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?
>
Yup. Looking at how the ttt TTML validator yells at you if you leave
it out, and what is noted in
https://www.w3.org/TR/ttml1/#content-attribute-langnot
> The xml:lang attribute must be specified on the tt element and may be
> specified by an instance of any other element type in the core vocabulary
> catalog except parameter vocabulary.
I then checked the XML specification regarding this and apparently an
empty string value is OK, so that's what we end up with.
> > + 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')?
>
Seems like a good way to do it.
> > + 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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