1 /*
2 * Copyright (c) 2010 Aurelien Jacobs <aurel@gnuage.org>
3 * Copyright (c) 2017 Clément Bœsch <u@pkh.me>
4 *
5 * This file is part of FFmpeg.
6 *
7 * FFmpeg is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU Lesser General Public
9 * License as published by the Free Software Foundation; either
10 * version 2.1 of the License, or (at your option) any later version.
11 *
12 * FFmpeg is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 * Lesser General Public License for more details.
16 *
17 * You should have received a copy of the GNU Lesser General Public
18 * License along with FFmpeg; if not, write to the Free Software
19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20 */
21
22 #include "libavutil/avassert.h"
23 #include "libavutil/avstring.h"
24 #include "libavutil/common.h"
25 #include "libavutil/parseutils.h"
26 #include "htmlsubtitles.h"
27 #include <ctype.h>
28
html_color_parse(void * log_ctx,const char * str)29 static int html_color_parse(void *log_ctx, const char *str)
30 {
31 uint8_t rgba[4];
32 int nb_sharps = 0;
33 while (str[nb_sharps] == '#')
34 nb_sharps++;
35 str += FFMAX(0, nb_sharps - 1);
36 if (av_parse_color(rgba, str, strcspn(str, "\" >"), log_ctx) < 0)
37 return -1;
38 return rgba[0] | rgba[1] << 8 | rgba[2] << 16;
39 }
40
rstrip_spaces_buf(AVBPrint * buf)41 static void rstrip_spaces_buf(AVBPrint *buf)
42 {
43 if (av_bprint_is_complete(buf))
44 while (buf->len > 0 && buf->str[buf->len - 1] == ' ')
45 buf->str[--buf->len] = 0;
46 }
47
48 /*
49 * Fast code for scanning text enclosed in braces. Functionally
50 * equivalent to this sscanf call:
51 *
52 * sscanf(in, "{\\an%*1u}%n", &len) >= 0 && len > 0
53 */
scanbraces(const char * in)54 static int scanbraces(const char* in) {
55 if (strncmp(in, "{\\an", 4) != 0) {
56 return 0;
57 }
58 if (!av_isdigit(in[4])) {
59 return 0;
60 }
61 if (in[5] != '}') {
62 return 0;
63 }
64 return 1;
65 }
66
67 /* skip all {\xxx} substrings except for {\an%d}
68 and all microdvd like styles such as {Y:xxx} */
handle_open_brace(AVBPrint * dst,const char ** inp,int * an,int * closing_brace_missing)69 static void handle_open_brace(AVBPrint *dst, const char **inp, int *an, int *closing_brace_missing)
70 {
71 const char *in = *inp;
72
73 *an += scanbraces(in);
74
75 if (!*closing_brace_missing) {
76 if ( (*an != 1 && in[1] == '\\')
77 || (in[1] && strchr("CcFfoPSsYy", in[1]) && in[2] == ':')) {
78 char *bracep = strchr(in+2, '}');
79 if (bracep) {
80 *inp = bracep;
81 return;
82 } else
83 *closing_brace_missing = 1;
84 }
85 }
86
87 av_bprint_chars(dst, *in, 1);
88 }
89
90 struct font_tag {
91 char face[128];
92 int size;
93 uint32_t color;
94 };
95
96 /*
97 * Fast code for scanning the rest of a tag. Functionally equivalent to
98 * this sscanf call:
99 *
100 * sscanf(in, "%127[^<>]>%n", buffer, lenp) == 2
101 */
scantag(const char * in,char * buffer,int * lenp)102 static int scantag(const char* in, char* buffer, int* lenp) {
103 int len;
104
105 for (len = 0; len < 128; len++) {
106 const char c = *in++;
107 switch (c) {
108 case '\0':
109 return 0;
110 case '<':
111 return 0;
112 case '>':
113 buffer[len] = '\0';
114 *lenp = len+1;
115 return 1;
116 default:
117 break;
118 }
119 buffer[len] = c;
120 }
121 return 0;
122 }
123
124 /*
125 * The general politic of the convert is to mask unsupported tags or formatting
126 * errors (but still alert the user/subtitles writer with an error/warning)
127 * without dropping any actual text content for the final user.
128 */
ff_htmlmarkup_to_ass(void * log_ctx,AVBPrint * dst,const char * in)129 int ff_htmlmarkup_to_ass(void *log_ctx, AVBPrint *dst, const char *in)
130 {
131 char *param, buffer[128];
132 int len, tag_close, sptr = 0, line_start = 1, an = 0, end = 0;
133 int closing_brace_missing = 0;
134 int i, likely_a_tag;
135
136 /*
137 * state stack is only present for fonts since they are the only tags where
138 * the state is not binary. Here is a typical use case:
139 *
140 * <font color="red" size=10>
141 * red 10
142 * <font size=50> RED AND BIG </font>
143 * red 10 again
144 * </font>
145 *
146 * On the other hand, using the state system for all the tags should be
147 * avoided because it breaks wrongly nested tags such as:
148 *
149 * <b> foo <i> bar </b> bla </i>
150 *
151 * We don't want to break here; instead, we will treat all these tags as
152 * binary state markers. Basically, "<b>" will activate bold, and "</b>"
153 * will deactivate it, whatever the current state.
154 *
155 * This will also prevents cases where we have a random closing tag
156 * remaining after the opening one was dropped. Yes, this happens and we
157 * still don't want to print a "</b>" at the end of the dialog event.
158 */
159 struct font_tag stack[16];
160
161 memset(&stack[0], 0, sizeof(stack[0]));
162
163 for (; !end && *in; in++) {
164 switch (*in) {
165 case '\r':
166 break;
167 case '\n':
168 if (line_start) {
169 end = 1;
170 break;
171 }
172 rstrip_spaces_buf(dst);
173 av_bprintf(dst, "\\N");
174 line_start = 1;
175 break;
176 case ' ':
177 if (!line_start)
178 av_bprint_chars(dst, *in, 1);
179 break;
180 case '{':
181 handle_open_brace(dst, &in, &an, &closing_brace_missing);
182 break;
183 case '<':
184 /*
185 * "<<" are likely latin guillemets in ASCII or some kind of random
186 * style effect; see sub/badsyntax.srt in the FATE samples
187 * directory for real test cases.
188 */
189
190 likely_a_tag = 1;
191 for (i = 0; in[1] == '<'; i++) {
192 av_bprint_chars(dst, '<', 1);
193 likely_a_tag = 0;
194 in++;
195 }
196
197 tag_close = in[1] == '/';
198 if (tag_close)
199 likely_a_tag = 1;
200
201 av_assert0(in[0] == '<');
202
203 len = 0;
204
205 if (scantag(in+tag_close+1, buffer, &len) && len > 0) {
206 const int skip = len + tag_close;
207 const char *tagname = buffer;
208 while (*tagname == ' ') {
209 likely_a_tag = 0;
210 tagname++;
211 }
212 if ((param = strchr(tagname, ' ')))
213 *param++ = 0;
214
215 /* Check if this is likely a tag */
216 #define LIKELY_A_TAG_CHAR(x) (((x) >= '0' && (x) <= '9') || \
217 ((x) >= 'a' && (x) <= 'z') || \
218 ((x) >= 'A' && (x) <= 'Z') || \
219 (x) == '_' || (x) == '/')
220 for (i = 0; tagname[i]; i++) {
221 if (!LIKELY_A_TAG_CHAR(tagname[i])) {
222 likely_a_tag = 0;
223 break;
224 }
225 }
226
227 if (!av_strcasecmp(tagname, "font")) {
228 if (tag_close && sptr > 0) {
229 struct font_tag *cur_tag = &stack[sptr--];
230 struct font_tag *last_tag = &stack[sptr];
231
232 if (cur_tag->size) {
233 if (!last_tag->size)
234 av_bprintf(dst, "{\\fs}");
235 else if (last_tag->size != cur_tag->size)
236 av_bprintf(dst, "{\\fs%d}", last_tag->size);
237 }
238
239 if (cur_tag->color & 0xff000000) {
240 if (!(last_tag->color & 0xff000000))
241 av_bprintf(dst, "{\\c}");
242 else if (last_tag->color != cur_tag->color)
243 av_bprintf(dst, "{\\c&H%"PRIX32"&}", last_tag->color & 0xffffff);
244 }
245
246 if (cur_tag->face[0]) {
247 if (!last_tag->face[0])
248 av_bprintf(dst, "{\\fn}");
249 else if (strcmp(last_tag->face, cur_tag->face))
250 av_bprintf(dst, "{\\fn%s}", last_tag->face);
251 }
252 } else if (!tag_close && sptr < FF_ARRAY_ELEMS(stack) - 1) {
253 struct font_tag *new_tag = &stack[sptr + 1];
254
255 *new_tag = stack[sptr++];
256
257 while (param) {
258 if (!av_strncasecmp(param, "size=", 5)) {
259 param += 5 + (param[5] == '"');
260 if (sscanf(param, "%u", &new_tag->size) == 1)
261 av_bprintf(dst, "{\\fs%u}", new_tag->size);
262 } else if (!av_strncasecmp(param, "color=", 6)) {
263 int color;
264 param += 6 + (param[6] == '"');
265 color = html_color_parse(log_ctx, param);
266 if (color >= 0) {
267 new_tag->color = 0xff000000 | color;
268 av_bprintf(dst, "{\\c&H%"PRIX32"&}", new_tag->color & 0xffffff);
269 }
270 } else if (!av_strncasecmp(param, "face=", 5)) {
271 param += 5 + (param[5] == '"');
272 len = strcspn(param,
273 param[-1] == '"' ? "\"" :" ");
274 av_strlcpy(new_tag->face, param,
275 FFMIN(sizeof(new_tag->face), len+1));
276 param += len;
277 av_bprintf(dst, "{\\fn%s}", new_tag->face);
278 }
279 if ((param = strchr(param, ' ')))
280 param++;
281 }
282 }
283 in += skip;
284 } else if (tagname[0] && !tagname[1] && strchr("bisu", av_tolower(tagname[0]))) {
285 av_bprintf(dst, "{\\%c%d}", (char)av_tolower(tagname[0]), !tag_close);
286 in += skip;
287 } else if (!av_strncasecmp(tagname, "br", 2) &&
288 (!tagname[2] || (tagname[2] == '/' && !tagname[3]))) {
289 av_bprintf(dst, "\\N");
290 in += skip;
291 } else if (likely_a_tag) {
292 if (!tag_close) // warn only once
293 av_log(log_ctx, AV_LOG_WARNING, "Unrecognized tag %s\n", tagname);
294 in += skip;
295 } else {
296 av_bprint_chars(dst, '<', 1);
297 }
298 } else {
299 av_bprint_chars(dst, *in, 1);
300 }
301 break;
302 default:
303 av_bprint_chars(dst, *in, 1);
304 break;
305 }
306 if (*in != ' ' && *in != '\r' && *in != '\n')
307 line_start = 0;
308 }
309
310 if (!av_bprint_is_complete(dst))
311 return AVERROR(ENOMEM);
312
313 while (dst->len >= 2 && !strncmp(&dst->str[dst->len - 2], "\\N", 2))
314 dst->len -= 2;
315 dst->str[dst->len] = 0;
316 rstrip_spaces_buf(dst);
317
318 return 0;
319 }
320