lavc/htmlsubtitles: improve handling broken garbage

This commit switches off forced correct nesting of tags and only keeps
it for font tags. See long explanations in the code for the rationale.

This results in various FATE changes which I'll explain here:

- various swapping in font attributes, this is mostly noise due to the
  old reverse stack way of printing them. The new one is more correct as
  the last attribute takes over the previous ones.

- unrecognized tags disappears

- invalid tags that were previously displayed aren't anymore (instead,
  we have a warning). This is better for the end user

The main benefit of this commit is to be more tolerant to error, leading
to a better handling of badly nested tags or random wrong formatting for
the end user.

libavcodec/htmlsubtitles.c

@@ -1,5 +1,6 @@
 /*
  * Copyright (c) 2010  Aurelien Jacobs <aurel@gnuage.org>
+ * Copyright (c) 2017  Clément Bœsch <u@pkh.me>
  *
  * This file is part of FFmpeg.
  *
@@ -18,6 +19,7 @@
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
+#include "libavutil/avassert.h"
 #include "libavutil/avstring.h"
 #include "libavutil/common.h"
 #include "libavutil/parseutils.h"
@@ -31,19 +33,6 @@ static int html_color_parse(void *log_ctx, const char *str)
     return rgba[0] | rgba[1] << 8 | rgba[2] << 16;
 }
 
-enum {
-    PARAM_UNKNOWN = -1,
-    PARAM_SIZE,
-    PARAM_COLOR,
-    PARAM_FACE,
-    PARAM_NUMBER
-};
-
-typedef struct SrtStack {
-    char tag[128];
-    char param[PARAM_NUMBER][128];
-} SrtStack;
-
 static void rstrip_spaces_buf(AVBPrint *buf)
 {
     if (av_bprint_is_complete(buf))
@@ -75,17 +64,50 @@ static void handle_open_brace(AVBPrint *dst, const char **inp, int *an, int *clo
     av_bprint_chars(dst, *in, 1);
 }
 
+struct font_tag {
+    char face[128];
+    int size;
+    uint32_t color;
+};
+
+/*
+ * The general politic of the convert is to mask unsupported tags or formatting
+ * errors (but still alert the user/subtitles writer with an error/warning)
+ * without dropping any actual text content for the final user.
+ */
 int ff_htmlmarkup_to_ass(void *log_ctx, AVBPrint *dst, const char *in)
 {
-    char *param, buffer[128], tmp[128];
+    char *param, buffer[128];
-    int len, tag_close, sptr = 1, line_start = 1, an = 0, end = 0;
+    int len, tag_close, sptr = 0, line_start = 1, an = 0, end = 0;
-    SrtStack stack[16];
     int closing_brace_missing = 0;
+    int i, likely_a_tag;
 
-    stack[0].tag[0] = 0;
+    /*
-    strcpy(stack[0].param[PARAM_SIZE],  "{\\fs}");
+     * state stack is only present for fonts since they are the only tags where
-    strcpy(stack[0].param[PARAM_COLOR], "{\\c}");
+     * the state is not binary. Here is a typical use case:
-    strcpy(stack[0].param[PARAM_FACE],  "{\\fn}");
+     *
+     *   <font color="red" size=10>
+     *     red 10
+     *     <font size=50> RED AND BIG </font>
+     *     red 10 again
+     *   </font>
+     *
+     * On the other hand, using the state system for all the tags should be
+     * avoided because it breaks wrongly nested tags such as:
+     *
+     *   <b> foo <i> bar </b> bla </i>
+     *
+     * We don't want to break here; instead, we will treat all these tags as
+     * binary state markers. Basically, "<b>" will activate bold, and "</b>"
+     * will deactivate it, whatever the current state.
+     *
+     * This will also prevents cases where we have a random closing tag
+     * remaining after the opening one was dropped. Yes, this happens and we
+     * still don't want to print a "</b>" at the end of the dialog event.
+     */
+    struct font_tag stack[16];
+
+    memset(&stack[0], 0, sizeof(stack[0]));
 
     for (; !end && *in; in++) {
         switch (*in) {
@@ -108,82 +130,127 @@ int ff_htmlmarkup_to_ass(void *log_ctx, AVBPrint *dst, const char *in)
             handle_open_brace(dst, &in, &an, &closing_brace_missing);
             break;
         case '<':
+            /*
+             * "<<" are likely latin guillemets in ASCII or some kind of random
+             * style effect; see sub/badsyntax.srt in the FATE samples
+             * directory for real test cases.
+             */
+
+            likely_a_tag = 1;
+            for (i = 0; in[1] == '<'; i++) {
+                av_bprint_chars(dst, '<', 1);
+                likely_a_tag = 0;
+                in++;
+            }
+
             tag_close = in[1] == '/';
+            if (tag_close)
+                likely_a_tag = 1;
+
+            av_assert0(in[0] == '<');
+
             len = 0;
+
             if (sscanf(in+tag_close+1, "%127[^<>]>%n", buffer, &len) >= 1 && len > 0) {
+                const int skip = len + tag_close;
                 const char *tagname = buffer;
-                while (*tagname == ' ')
+                while (*tagname == ' ') {
+                    likely_a_tag = 0;
                     tagname++;
+                }
                 if ((param = strchr(tagname, ' ')))
                     *param++ = 0;
-                if ((!tag_close && sptr < FF_ARRAY_ELEMS(stack) && *tagname) ||
+
-                    ( tag_close && sptr > 0 && !av_strcasecmp(stack[sptr-1].tag, tagname))) {
+                /* Check if this is likely a tag */
-                    int i, j, unknown = 0;
+#define LIKELY_A_TAG_CHAR(x) (((x) >= '0' && (x) <= '9') || \
-                    in += len + tag_close;
+                              ((x) >= 'a' && (x) <= 'z') || \
-                    if (!tag_close)
+                              ((x) >= 'A' && (x) <= 'Z') || \
-                        memset(stack+sptr, 0, sizeof(*stack));
+                               (x) == '_')
-                    if (!av_strcasecmp(tagname, "font")) {
+                for (i = 0; tagname[i]; i++) {
-                        if (tag_close) {
+                    if (!LIKELY_A_TAG_CHAR(tagname[i])) {
-                            for (i=PARAM_NUMBER-1; i>=0; i--)
+                        likely_a_tag = 0;
-                                if (stack[sptr-1].param[i][0])
+                        break;
-                                    for (j=sptr-2; j>=0; j--)
+                    }
-                                        if (stack[j].param[i][0]) {
+                }
-                                            av_bprintf(dst, "%s", stack[j].param[i]);
+
-                                            break;
+                // TODO: reindent
-                                        }
+
-                        } else {
+                if (!av_strcasecmp(tagname, "font")) {
+                    if (tag_close && sptr > 0) {
+                        struct font_tag *cur_tag  = &stack[sptr--];
+                        struct font_tag *last_tag = &stack[sptr];
+
+                        if (cur_tag->size) {
+                            if (!last_tag->size)
+                                av_bprintf(dst, "{\\fs}");
+                            else if (last_tag->size != cur_tag->size)
+                                av_bprintf(dst, "{\\fs%d}", last_tag->size);
+                        }
+
+                        if (cur_tag->color & 0xff000000) {
+                            if (!(last_tag->color & 0xff000000))
+                                av_bprintf(dst, "{\\c}");
+                            else if (last_tag->color != cur_tag->color)
+                                av_bprintf(dst, "{\\c&H%X&}", last_tag->color & 0xffffff);
+                        }
+
+                        if (cur_tag->face[0]) {
+                            if (!last_tag->face[0])
+                                av_bprintf(dst, "{\\fn}");
+                            else if (strcmp(last_tag->face, cur_tag->face))
+                                av_bprintf(dst, "{\\fn%s}", last_tag->face);
+                        }
+                    } else if (!tag_close && sptr < FF_ARRAY_ELEMS(stack) - 1) {
+                        struct font_tag *new_tag = &stack[sptr + 1];
+
+                        *new_tag = stack[sptr++];
+
                             while (param) {
                                 if (!av_strncasecmp(param, "size=", 5)) {
-                                    unsigned font_size;
                                     param += 5 + (param[5] == '"');
-                                    if (sscanf(param, "%u", &font_size) == 1) {
+                                    if (sscanf(param, "%u", &new_tag->size) == 1)
-                                        snprintf(stack[sptr].param[PARAM_SIZE],
+                                        av_bprintf(dst, "{\\fs%u}", new_tag->size);
-                                             sizeof(stack[0].param[PARAM_SIZE]),
-                                             "{\\fs%u}", font_size);
-                                    }
                                 } else if (!av_strncasecmp(param, "color=", 6)) {
+                                    int color;
                                     param += 6 + (param[6] == '"');
-                                    snprintf(stack[sptr].param[PARAM_COLOR],
+                                    color = html_color_parse(log_ctx, param);
-                                         sizeof(stack[0].param[PARAM_COLOR]),
+                                    if (color >= 0) {
-                                         "{\\c&H%X&}",
+                                        new_tag->color = 0xff000000 | color;
-                                         html_color_parse(log_ctx, param));
+                                        av_bprintf(dst, "{\\c&H%X&}", new_tag->color & 0xffffff);
+                                    }
                                 } else if (!av_strncasecmp(param, "face=", 5)) {
                                     param += 5 + (param[5] == '"');
                                     len = strcspn(param,
                                                   param[-1] == '"' ? "\"" :" ");
-                                    av_strlcpy(tmp, param,
+                                    av_strlcpy(new_tag->face, param,
-                                               FFMIN(sizeof(tmp), len+1));
+                                               FFMIN(sizeof(new_tag->face), len+1));
                                     param += len;
-                                    snprintf(stack[sptr].param[PARAM_FACE],
+                                    av_bprintf(dst, "{\\fn%s}", new_tag->face);
-                                             sizeof(stack[0].param[PARAM_FACE]),
-                                             "{\\fn%s}", tmp);
                                 }
                                 if ((param = strchr(param, ' ')))
                                     param++;
                             }
-                            for (i=0; i<PARAM_NUMBER; i++)
-                                if (stack[sptr].param[i][0])
-                                    av_bprintf(dst, "%s", stack[sptr].param[i]);
                         }
+
+                    in += skip;
+
                     } else if (tagname[0] && !tagname[1] && strchr("bisu", av_tolower(tagname[0]))) {
                         av_bprintf(dst, "{\\%c%d}", (char)av_tolower(tagname[0]), !tag_close);
+                        in += skip;
                     } else if (!av_strcasecmp(tagname, "br")) {
                         av_bprintf(dst, "\\N");
+                        in += skip;
+                    } else if (likely_a_tag) {
+                        if (!tag_close) // warn only once
+                            av_log(log_ctx, AV_LOG_WARNING, "Unrecognized tag %s\n", tagname);
+                        in += skip;
                     } else {
-                        unknown = 1;
+                        av_bprint_chars(dst, '<', 1);
-                        snprintf(tmp, sizeof(tmp), "</%s>", tagname);
-                    }
-                    if (tag_close) {
-                        sptr--;
-                    } else if (unknown && !strstr(in, tmp)) {
-                        in -= len + tag_close;
-                        av_bprint_chars(dst, *in, 1);
-                    } else
-                        av_strlcpy(stack[sptr++].tag, tagname,
-                                   sizeof(stack[0].tag));
-                    break;
                 }
+            } else {
+                av_bprint_chars(dst, *in, 1);
             }
+            break;
         default:
             av_bprint_chars(dst, *in, 1);
             break;

tests/ref/fate/sub-sami2

@@ -19,7 +19,7 @@ Dialogue: 0,0:00:17.67,0:00:21.72,Default,,0,0,0,,\N{\c&HCBC0FF&}{\fs6}It's{\fs}
 Dialogue: 0,0:00:21.84,0:00:21.84,Default,,0,0,0,,\N{\u1}매력적인 세계에서\N이 모든 것이 펼쳐집니다{\u1}
 Dialogue: 0,0:00:21.84,0:00:23.58,Default,,0,0,0,,\N{\i1}{\c&H9966CC&}of{\c}{\c&HC2A3E0&} what's{\c} {\c&HE0D1F0&}right{\c} {\c&HFCFAFE&}and{\c} wrong.{\i0}
 Dialogue: 0,0:00:23.69,0:00:23.69,Default,,0,0,0,,\N{\i1}이 주제를 심오한 철학으로\N담아내고 있어요{\i0}
-Dialogue: 0,0:00:23.69,0:00:25.67,Default,,0,0,0,,\N{\fs20}{\c&HFF0000&}{\s1}It{\s0}{\c}{\fs} has {\fs15}{\c&HFFFF00&}a{\c}{\fs} great {\fs16}{\c&HFFCC00&}philosophy{\c}{\fs} about it.
+Dialogue: 0,0:00:23.69,0:00:25.67,Default,,0,0,0,,\N{\c&HFF0000&}{\fs20}{\s1}It{\s0}{\fs}{\c} has {\c&HFFFF00&}{\fs15}a{\fs}{\c} great {\c&HFFCC00&}{\fs16}philosophy{\fs}{\c} about it.
 Dialogue: 0,0:00:40.22,0:00:40.22,Default,,0,0,0,,\N{\s1}"왕좌의 게임"은 웨스테로스라는 가상왕국의\N권력 분쟁 이야기입니다{\s0}
 Dialogue: 0,0:00:40.22,0:00:47.94,Default,,0,0,0,,\N{\c&HA5FF&}{\fs26}"Game of Thrones"{\fs}{\c} {\c&H2A2AA5&}{\b1}is{\b0}{\c}{\c&HFFFF&}{\fs24}{\i1} about{\i0}{\fs}{\c} {\c&H336699&}{\fs14}power{\fs}{\c}{\c&HFF&} struggles{\c}\N{\c&HA5FF&}{\fs8}in a fantasy{\fs}{\c&HCBC0FF&} kingdom{\c&HA5FF&}, called {\fs6}Westeros.{\fs}{\c}
 Dialogue: 0,0:00:48.06,0:00:48.06,Default,,0,0,0,,\N철의 왕좌를 둘러싼\N권력 분쟁이죠
@@ -51,7 +51,7 @@ Dialogue: 0,0:01:28.98,0:01:33.89,Default,,0,0,0,,\N{\u1}this common threat, tha
 Dialogue: 0,0:01:34.01,0:01:35.24,Default,,0,0,0,,\Npursuing their own interests.
 Dialogue: 0,0:01:35.36,0:01:35.36,Default,,0,0,0,,\N한편, 일곱 왕국의 밖에서는\N두 개의 거대한 위협이 부상합니다
 Dialogue: 0,0:01:35.36,0:01:40.23,Default,,0,0,0,,\N{\fs30}And meanwhile, outside the Seven\NKingdoms, two great threats arising.{\fs}
-Dialogue: 0,0:01:40.35,0:01:40.35,Default,,0,0,0,,\N<sup>하나는 바다 건너\N타가리엔 일족 유배자들이며</sub>
+Dialogue: 0,0:01:40.35,0:01:40.35,Default,,0,0,0,,\N하나는 바다 건너\N타가리엔 일족 유배자들이며
 Dialogue: 0,0:01:40.35,0:01:44.06,Default,,0,0,0,,\NOne across the sea, in the exile\NTargaryen siblings,
 Dialogue: 0,0:01:44.17,0:01:44.17,Default,,0,0,0,,\N또 하나는 일곱 왕국의\N국경이 자리잡은
 Dialogue: 0,0:01:44.17,0:01:47.39,Default,,0,0,0,,\Nand another far to the north,\Nbeyond the Wall,

tests/ref/fate/sub-srt

@@ -14,10 +14,10 @@ Dialogue: 0,0:00:00.00,0:00:00.00,Default,,0,0,0,,Don't show this text it may be
 Dialogue: 0,0:00:01.50,0:00:04.50,Default,,0,0,0,,SubRip subtitles capability tester 1.3o by ale5000\N{\b1}{\i1}Use VLC 1.1 or higher as reference for most things and MPC Home Cinema for others{\i0}{\b0}\N{\c&HFF0000&}This text should be blue{\c}\N{\c&HFF&}This text should be red{\c}\N{\c&H0&}This text should be black{\c}\N{\fnWebdings}If you see this with the normal font, the player don't (fully) support font face{\fn}
 Dialogue: 0,0:00:04.50,0:00:04.50,Default,,0,0,0,,Hidden
 Dialogue: 0,0:00:04.50,0:00:07.50,Default,,0,0,0,,{\fs8}This text should be small{\fs}\NThis text should be normal\N{\fs35}This text should be big{\fs}
-Dialogue: 0,0:00:07.50,0:00:11.50,Default,,0,0,0,,This should be an E with an accent: È\N日本語\N{\fs30}{\b1}{\i1}{\u1}This text should be bold, italics and underline{\u0}{\i0}{\b0}{\fs}\N{\fs9}{\c&HFF00&}This text should be small and green{\c}{\fs}\N{\fs9}{\c&HFF&}This text should be small and red{\c}{\fs}\N{\fs24}{\c&H2A2AA5&}This text should be big and brown{\c}{\fs}
+Dialogue: 0,0:00:07.50,0:00:11.50,Default,,0,0,0,,This should be an E with an accent: È\N日本語\N{\fs30}{\b1}{\i1}{\u1}This text should be bold, italics and underline{\u0}{\i0}{\b0}{\fs}\N{\fs9}{\c&HFF00&}This text should be small and green{\fs}{\c}\N{\c&HFF&}{\fs9}This text should be small and red{\fs}{\c}\N{\c&H2A2AA5&}{\fs24}This text should be big and brown{\fs}{\c}
 Dialogue: 0,0:00:11.50,0:00:14.50,Default,,0,0,0,,{\b1}This line should be bold{\b0}\N{\i1}This line should be italics{\i0}\N{\u1}This line should be underline{\u0}\N{\s1}This line should be strikethrough{\s0}\N{\u1}Both lines\Nshould be underline{\u0}
-Dialogue: 0,0:00:14.50,0:00:17.50,Default,,0,0,0,,>\NIt would be a good thing to\Nhide invalid html tags that are closed and show the text in them\N<invalid_tag_unclosed>but show un-closed invalid html tags\NShow not opened tags</invalid_tag_not_opened>\N<
+Dialogue: 0,0:00:14.50,0:00:17.50,Default,,0,0,0,,>\NIt would be a good thing to\Nhide invalid html tags that are closed and show the text in them\Nbut show un-closed invalid html tags\NShow not opened tags\N<
-Dialogue: 0,0:00:17.50,0:00:20.50,Default,,0,0,0,,and also\Nhide invalid html tags with parameters that are closed and show the text in them\N<invalid_tag_uc par=5>but show un-closed invalid html tags\N{\u1}This text should be showed underlined without problems also: 2<3,5>1,4<6{\u0}\NThis shouldn't be underlined
+Dialogue: 0,0:00:17.50,0:00:20.50,Default,,0,0,0,,and also\Nhide invalid html tags with parameters that are closed and show the text in them\Nbut show un-closed invalid html tags\N{\u1}This text should be showed underlined without problems also: 2<3,5>1,4<6{\u0}\NThis shouldn't be underlined
 Dialogue: 0,0:00:20.50,0:00:21.50,Default,,0,0,0,,This text should be in the normal position...
 Dialogue: 0,0:00:21.50,0:00:22.50,Default,,0,0,0,,{\an5}{\pos(0,45)}This text should NOT be in the normal position
 Dialogue: 0,0:00:22.50,0:00:24.50,Default,,0,0,0,,Implementation is the same of the ASS tag\N{\an8}This text should be at the\Ntop and horizontally centered
@@ -29,7 +29,7 @@ Dialogue: 0,0:00:24.50,0:00:26.50,Default,,0,0,0,,{\an1}This text should be at t
 Dialogue: 0,0:00:26.50,0:00:28.50,Default,,0,0,0,,{\an9}This text should be at the\Ntop and horizontally at the right
 Dialogue: 0,0:00:26.50,0:00:28.50,Default,,0,0,0,,{\an6}This text should be at the\Nmiddle and horizontally at the right
 Dialogue: 0,0:00:26.50,0:00:28.50,Default,,0,0,0,,{\an3}This text should be at the\Nbottom and horizontally at the right
-Dialogue: 0,0:00:28.50,0:00:31.50,Default,,0,0,0,,{\fs6}{\c&HFF00&}This could be the {\fs35}m{\c&H0&}o{\c&HFF00&}st{\fs6} difficult thing to implement{\c}{\fs}
+Dialogue: 0,0:00:28.50,0:00:31.50,Default,,0,0,0,,{\c&HFF00&}{\fs6}This could be the {\fs35}m{\c&H0&}o{\c&HFF00&}st{\fs6} difficult thing to implement{\fs}{\c}
 Dialogue: 0,0:00:31.50,0:00:50.50,Default,,0,0,0,,First text
 Dialogue: 0,0:00:33.50,0:00:35.50,Default,,0,0,0,,Second, it shouldn't overlap first
 Dialogue: 0,0:00:35.50,0:00:37.50,Default,,0,0,0,,Third, it should replace second
@@ -44,6 +44,6 @@ Dialogue: 0,0:00:54.50,0:00:56.50,Default,,0,0,0,,{\an1}\N\h\h\h\h\hA (05 hard s
 Dialogue: 0,0:00:56.50,0:00:58.50,Default,,0,0,0,,\h\h\h\h\hA (05 hard spaces followed by a letter)\NA (Normal  spaces followed by a letter)\NA (No hard spaces followed by a letter)\NShow this: \TEST and this: \-)
 Dialogue: 0,0:00:58.50,0:01:00.50,Default,,0,0,0,,{\an3}\NA letter followed by 05 hard spaces: A\h\h\h\h\h\NA letter followed by normal  spaces: A\NA letter followed by no hard spaces: A\N05 hard  spaces between letters: A\h\h\h\h\hA\N5 normal spaces between letters: A     A\N\N^--Forced line break
 Dialogue: 0,0:01:00.50,0:01:02.50,Default,,0,0,0,,{\s1}Both line should be strikethrough,\Nyes.{\s0}\NCorrectly closed tags\Nshould be hidden.
-Dialogue: 0,0:01:02.50,0:01:04.50,Default,,0,0,0,,It shouldn't be strikethrough,\Nnot opened tag showed as text.</s>\NNot opened tag showed as text.</xxxxx>
+Dialogue: 0,0:01:02.50,0:01:04.50,Default,,0,0,0,,It shouldn't be strikethrough,\Nnot opened tag showed as text.{\s0}\NNot opened tag showed as text.
-Dialogue: 0,0:01:04.50,0:01:06.50,Default,,0,0,0,,{\s1}Three lines should be strikethrough,\Nyes.\N<yyyy>Not closed tags showed as text
+Dialogue: 0,0:01:04.50,0:01:06.50,Default,,0,0,0,,{\s1}Three lines should be strikethrough,\Nyes.\NNot closed tags showed as text
-Dialogue: 0,0:01:06.50,0:01:08.50,Default,,0,0,0,,{\s1}Both line should be strikethrough but\Nthe wrong closing tag should be showed</b>
+Dialogue: 0,0:01:06.50,0:01:08.50,Default,,0,0,0,,{\s1}Both line should be strikethrough but\Nthe wrong closing tag should be showed{\b0}

tests/ref/fate/sub-srt-badsyntax

@@ -14,8 +14,8 @@ Dialogue: 0,0:00:01.00,0:00:02.31,Default,,0,0,0,,<<<<<< Antes <<<<<<\NEla é hu
 Dialogue: 0,0:01:10.00,0:01:14.50,Default,,0,0,0,,>>> RebelSubTeam <<<
 Dialogue: 0,0:02:37.75,0:02:43.70,Default,,0,0,0,,{\b1}~ASUKO MARCH!~\N>>:<<\Ntranslation by: cangii\NRetiming by: furransu{\b0}
 Dialogue: 0,0:03:38.32,0:03:42.78,Default,,0,0,0,,<<THE HIGH ROLLERS>>\N<<Grandes Jogadores>>
-Dialogue: 0,0:04:50.43,0:05:01.03,Default,,0,0,0,,<<flash gordon\N<E9>pisode 4\Nsaison 1>\Nwww.SeriesSub.com>
+Dialogue: 0,0:04:50.43,0:05:01.03,Default,,0,0,0,,<<flash gordon\Npisode 4\Nsaison 1>\Nwww.SeriesSub.com>
-Dialogue: 0,0:20:31.85,0:20:56.84,Default,,0,0,0,,{\c&HFFFFFFFF&}\N<<<<www.egfire.com>>>>{\c}
+Dialogue: 0,0:20:31.85,0:20:56.84,Default,,0,0,0,,\N<<<<www.egfire.com>>>>
 Dialogue: 0,0:37:59.69,0:38:01.59,Default,,0,0,0,,mint asztalt foglaltatni\Na <<>Le Cirque-ben.
 Dialogue: 0,0:53:43.78,0:53:45.94,Default,,0,0,0,,<<That's OK, >> - he calmed himself.
 Dialogue: 0,0:53:46.22,0:53:49.09,Default,,0,0,0,,<<lt's not a long way to the hotel,\Nthe hotel is within easy reach.

tests/ref/fate/sub-textenc

@@ -44,15 +44,15 @@ should be underline
 >
 It would be a good thing to
 hide invalid html tags that are closed and show the text in them
-<invalid_tag_unclosed>but show un-closed invalid html tags
+but show un-closed invalid html tags
-Show not opened tags</invalid_tag_not_opened>
+Show not opened tags
 <
 
 8
 00:00:17,501 --> 00:00:20,500
 and also
 hide invalid html tags with parameters that are closed and show the text in them
-<invalid_tag_uc par=5>but show un-closed invalid html tags
+but show un-closed invalid html tags
 This text should be showed underlined without problems also: 2<3,5>1,4<6
 This shouldn't be underlined
 
@@ -197,17 +197,17 @@ should be hidden.
 35
 00:01:02,501 --> 00:01:04,500
 It shouldn't be strikethrough,
-not opened tag showed as text.</s>
+not opened tag showed as text.
-Not opened tag showed as text.</xxxxx>
+Not opened tag showed as text.
 
 36
 00:01:04,501 --> 00:01:06,500
 Three lines should be strikethrough,
 yes.
-<yyyy>Not closed tags showed as text
+Not closed tags showed as text
 
 37
 00:01:06,501 --> 00:01:08,500
 Both line should be strikethrough but
-the wrong closing tag should be showed</b>
+the wrong closing tag should be showed
 

tests/ref/fate/sub-webvttenc

@@ -39,14 +39,14 @@ should be underline</u>
 >
 It would be a good thing to
 hide invalid html tags that are closed and show the text in them
-<invalid_tag_unclosed>but show un-closed invalid html tags
+but show un-closed invalid html tags
-Show not opened tags</invalid_tag_not_opened>
+Show not opened tags
 <
 
 00:17.501 --> 00:20.500
 and also
 hide invalid html tags with parameters that are closed and show the text in them
-<invalid_tag_uc par=5>but show un-closed invalid html tags
+but show un-closed invalid html tags
 <u>This text should be showed underlined without problems also: 2<3,5>1,4<6</u>
 This shouldn't be underlined
 
@@ -164,14 +164,14 @@ should be hidden.
 
 01:02.501 --> 01:04.500
 It shouldn't be strikethrough,
-not opened tag showed as text.</s>
+not opened tag showed as text.
-Not opened tag showed as text.</xxxxx>
+Not opened tag showed as text.
 
 01:04.501 --> 01:06.500
 Three lines should be strikethrough,
 yes.
-<yyyy>Not closed tags showed as text
+Not closed tags showed as text
 
 01:06.501 --> 01:08.500
 Both line should be strikethrough but
-the wrong closing tag should be showed</b>
+the wrong closing tag should be showed