FFmpeg coverage


Directory: ../../../ffmpeg/
File: src/libavcodec/ttmlenc.c
Date: 2021-09-24 20:55:06
Exec Total Coverage
Lines: 132 179 73.7%
Branches: 33 72 45.8%

Line Branch Exec Source
1 /*
2 * TTML subtitle encoder
3 * Copyright (c) 2020 24i
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 /**
23 * @file
24 * TTML subtitle encoder
25 * @see https://www.w3.org/TR/ttml1/
26 * @see https://www.w3.org/TR/ttml2/
27 * @see https://www.w3.org/TR/ttml-imsc/rec
28 */
29
30 #include "avcodec.h"
31 #include "internal.h"
32 #include "libavutil/avstring.h"
33 #include "libavutil/bprint.h"
34 #include "libavutil/internal.h"
35 #include "ass_split.h"
36 #include "ass.h"
37 #include "ttmlenc.h"
38
39 typedef struct {
40 AVCodecContext *avctx;
41 ASSSplitContext *ass_ctx;
42 AVBPrint buffer;
43 } TTMLContext;
44
45 306 static void ttml_text_cb(void *priv, const char *text, int len)
46 {
47 306 TTMLContext *s = priv;
48 306 AVBPrint cur_line = { 0 };
49 306 AVBPrint *buffer = &s->buffer;
50
51 306 av_bprint_init(&cur_line, len, AV_BPRINT_SIZE_UNLIMITED);
52
53 306 av_bprint_append_data(&cur_line, text, len);
54
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306 if (!av_bprint_is_complete(&cur_line)) {
55 av_log(s->avctx, AV_LOG_ERROR,
56 "Failed to move the current subtitle dialog to AVBPrint!\n");
57 av_bprint_finalize(&cur_line, NULL);
58 return;
59 }
60
61
62 306 av_bprint_escape(buffer, cur_line.str, NULL, AV_ESCAPE_MODE_XML,
63 0);
64
65 306 av_bprint_finalize(&cur_line, NULL);
66 }
67
68 195 static void ttml_new_line_cb(void *priv, int forced)
69 {
70 195 TTMLContext *s = priv;
71
72 195 av_bprintf(&s->buffer, "<br/>");
73 195 }
74
75 static const ASSCodesCallbacks ttml_callbacks = {
76 .text = ttml_text_cb,
77 .new_line = ttml_new_line_cb,
78 };
79
80 111 static int ttml_encode_frame(AVCodecContext *avctx, uint8_t *buf,
81 int bufsize, const AVSubtitle *sub)
82 {
83 111 TTMLContext *s = avctx->priv_data;
84 ASSDialog *dialog;
85 int i;
86
87 111 av_bprint_clear(&s->buffer);
88
89
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222 for (i=0; i<sub->num_rects; i++) {
90 111 const char *ass = sub->rects[i]->ass;
91 int ret;
92
93
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111 if (sub->rects[i]->type != SUBTITLE_ASS) {
94 av_log(avctx, AV_LOG_ERROR, "Only SUBTITLE_ASS type supported.\n");
95 return AVERROR(EINVAL);
96 }
97
98 111 dialog = ff_ass_split_dialog(s->ass_ctx, ass);
99
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111 if (!dialog)
100 return AVERROR(ENOMEM);
101
102
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111 if (dialog->style) {
103 111 av_bprintf(&s->buffer, "<span region=\"");
104 111 av_bprint_escape(&s->buffer, dialog->style, NULL,
105 AV_ESCAPE_MODE_XML,
106 AV_ESCAPE_FLAG_XML_DOUBLE_QUOTES);
107 111 av_bprintf(&s->buffer, "\">");
108 }
109
110 111 ret = ff_ass_split_override_codes(&ttml_callbacks, s, dialog->text);
111
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111 if (ret < 0) {
112 int log_level = (ret != AVERROR_INVALIDDATA ||
113 avctx->err_recognition & AV_EF_EXPLODE) ?
114 AV_LOG_ERROR : AV_LOG_WARNING;
115 av_log(avctx, log_level,
116 "Splitting received ASS dialog text %s failed: %s\n",
117 dialog->text,
118 av_err2str(ret));
119
120 if (log_level == AV_LOG_ERROR) {
121 ff_ass_free_dialog(&dialog);
122 return ret;
123 }
124 }
125
126
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111 if (dialog->style)
127 111 av_bprintf(&s->buffer, "</span>");
128
129 111 ff_ass_free_dialog(&dialog);
130 }
131
132
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111 if (!av_bprint_is_complete(&s->buffer))
133 return AVERROR(ENOMEM);
134
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111 if (!s->buffer.len)
135 return 0;
136
137 // force null-termination, so in case our destination buffer is
138 // too small, the return value is larger than bufsize minus null.
139
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111 if (av_strlcpy(buf, s->buffer.str, bufsize) > bufsize - 1) {
140 av_log(avctx, AV_LOG_ERROR, "Buffer too small for TTML event.\n");
141 return AVERROR_BUFFER_TOO_SMALL;
142 }
143
144 111 return s->buffer.len;
145 }
146
147 3 static av_cold int ttml_encode_close(AVCodecContext *avctx)
148 {
149 3 TTMLContext *s = avctx->priv_data;
150
151 3 ff_ass_split_free(s->ass_ctx);
152
153 3 av_bprint_finalize(&s->buffer, NULL);
154
155 3 return 0;
156 }
157
158 3 static const char *ttml_get_display_alignment(int alignment)
159 {
160
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3 switch (alignment) {
161 3 case 1:
162 case 2:
163 case 3:
164 3 return "after";
165 case 4:
166 case 5:
167 case 6:
168 return "center";
169 case 7:
170 case 8:
171 case 9:
172 return "before";
173 default:
174 return NULL;
175 }
176 }
177
178 3 static const char *ttml_get_text_alignment(int alignment)
179 {
180
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3 switch (alignment) {
181 case 1:
182 case 4:
183 case 7:
184 return "left";
185 3 case 2:
186 case 5:
187 case 8:
188 3 return "center";
189 case 3:
190 case 6:
191 case 9:
192 return "right";
193 default:
194 return NULL;
195 }
196 }
197
198 3 static void ttml_get_origin(ASSScriptInfo script_info, ASSStyle style,
199 int *origin_left, int *origin_top)
200 {
201 3 *origin_left = av_rescale(style.margin_l, 100, script_info.play_res_x);
202 3 *origin_top =
203 3 av_rescale((style.alignment >= 7) ? style.margin_v : 0,
204
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3 100, script_info.play_res_y);
205 3 }
206
207 3 static void ttml_get_extent(ASSScriptInfo script_info, ASSStyle style,
208 int *width, int *height)
209 {
210 3 *width = av_rescale(script_info.play_res_x - style.margin_r,
211 3 100, script_info.play_res_x);
212 9 *height = av_rescale((style.alignment <= 3) ?
213 3 script_info.play_res_y - style.margin_v :
214 script_info.play_res_y,
215
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3 100, script_info.play_res_y);
216 3 }
217
218 3 static int ttml_write_region(AVCodecContext *avctx, AVBPrint *buf,
219 ASSScriptInfo script_info, ASSStyle style)
220 {
221 3 const char *display_alignment = NULL;
222 3 const char *text_alignment = NULL;
223 3 int origin_left = 0;
224 3 int origin_top = 0;
225 3 int width = 0;
226 3 int height = 0;
227
228
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3 if (!style.name) {
229 av_log(avctx, AV_LOG_ERROR, "Subtitle style name not set!\n");
230 return AVERROR_INVALIDDATA;
231 }
232
233
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3 if (style.font_size < 0) {
234 av_log(avctx, AV_LOG_ERROR, "Invalid font size for TTML: %d!\n",
235 style.font_size);
236 return AVERROR_INVALIDDATA;
237 }
238
239
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3 if (style.margin_l < 0 || style.margin_r < 0 || style.margin_v < 0) {
240 av_log(avctx, AV_LOG_ERROR,
241 "One or more negative margin values in subtitle style: "
242 "left: %d, right: %d, vertical: %d!\n",
243 style.margin_l, style.margin_r, style.margin_v);
244 return AVERROR_INVALIDDATA;
245 }
246
247 3 display_alignment = ttml_get_display_alignment(style.alignment);
248 3 text_alignment = ttml_get_text_alignment(style.alignment);
249
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3 if (!display_alignment || !text_alignment) {
250 av_log(avctx, AV_LOG_ERROR,
251 "Failed to convert ASS style alignment %d of style %s to "
252 "TTML display and text alignment!\n",
253 style.alignment,
254 style.name);
255 return AVERROR_INVALIDDATA;
256 }
257
258 3 ttml_get_origin(script_info, style, &origin_left, &origin_top);
259 3 ttml_get_extent(script_info, style, &width, &height);
260
261 3 av_bprintf(buf, " <region xml:id=\"");
262 3 av_bprint_escape(buf, style.name, NULL, AV_ESCAPE_MODE_XML,
263 AV_ESCAPE_FLAG_XML_DOUBLE_QUOTES);
264 3 av_bprintf(buf, "\"\n");
265
266 3 av_bprintf(buf, " tts:origin=\"%d%% %d%%\"\n",
267 origin_left, origin_top);
268 3 av_bprintf(buf, " tts:extent=\"%d%% %d%%\"\n",
269 width, height);
270
271 3 av_bprintf(buf, " tts:displayAlign=\"");
272 3 av_bprint_escape(buf, display_alignment, NULL, AV_ESCAPE_MODE_XML,
273 AV_ESCAPE_FLAG_XML_DOUBLE_QUOTES);
274 3 av_bprintf(buf, "\"\n");
275
276 3 av_bprintf(buf, " tts:textAlign=\"");
277 3 av_bprint_escape(buf, text_alignment, NULL, AV_ESCAPE_MODE_XML,
278 AV_ESCAPE_FLAG_XML_DOUBLE_QUOTES);
279 3 av_bprintf(buf, "\"\n");
280
281 // if we set cell resolution to our script reference resolution,
282 // then a single line is a single "point" on our canvas. Thus, by setting
283 // our font size to font size in cells, we should gain a similar enough
284 // scale without resorting to explicit pixel based font sizing, which is
285 // frowned upon in the TTML community.
286 3 av_bprintf(buf, " tts:fontSize=\"%dc\"\n",
287 style.font_size);
288
289
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3 if (style.font_name) {
290 3 av_bprintf(buf, " tts:fontFamily=\"");
291 3 av_bprint_escape(buf, style.font_name, NULL, AV_ESCAPE_MODE_XML,
292 AV_ESCAPE_FLAG_XML_DOUBLE_QUOTES);
293 3 av_bprintf(buf, "\"\n");
294 }
295
296 3 av_bprintf(buf, " tts:overflow=\"visible\" />\n");
297
298 3 return 0;
299 }
300
301 3 static int ttml_write_header_content(AVCodecContext *avctx)
302 {
303 3 TTMLContext *s = avctx->priv_data;
304 3 ASS *ass = (ASS *)s->ass_ctx;
305 3 ASSScriptInfo script_info = ass->script_info;
306 3 const size_t base_extradata_size = TTMLENC_EXTRADATA_SIGNATURE_SIZE + 1 +
307 AV_INPUT_BUFFER_PADDING_SIZE;
308 3 size_t additional_extradata_size = 0;
309
310
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3 if (script_info.play_res_x <= 0 || script_info.play_res_y <= 0) {
311 av_log(avctx, AV_LOG_ERROR,
312 "Invalid subtitle reference resolution %dx%d!\n",
313 script_info.play_res_x, script_info.play_res_y);
314 return AVERROR_INVALIDDATA;
315 }
316
317 // write the first string in extradata, attributes in the base "tt" element.
318 3 av_bprintf(&s->buffer, ttml_default_namespacing);
319 // the cell resolution is in character cells, so not exactly 1:1 against
320 // a pixel based resolution, but as the tts:extent in the root
321 // "tt" element is frowned upon (and disallowed in the EBU-TT profile),
322 // we mimic the reference resolution by setting it as the cell resolution.
323 3 av_bprintf(&s->buffer, " ttp:cellResolution=\"%d %d\"\n",
324 script_info.play_res_x, script_info.play_res_y);
325 3 av_bprint_chars(&s->buffer, '\0', 1);
326
327 // write the second string in extradata, head element containing the styles
328 3 av_bprintf(&s->buffer, " <head>\n");
329 3 av_bprintf(&s->buffer, " <layout>\n");
330
331
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6 for (int i = 0; i < ass->styles_count; i++) {
332 3 int ret = ttml_write_region(avctx, &s->buffer, script_info,
333 3 ass->styles[i]);
334
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3 if (ret < 0)
335 return ret;
336 }
337
338 3 av_bprintf(&s->buffer, " </layout>\n");
339 3 av_bprintf(&s->buffer, " </head>\n");
340 3 av_bprint_chars(&s->buffer, '\0', 1);
341
342
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3 if (!av_bprint_is_complete(&s->buffer)) {
343 return AVERROR(ENOMEM);
344 }
345
346 3 additional_extradata_size = s->buffer.len;
347
348
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3 if (!(avctx->extradata =
349 3 av_mallocz(base_extradata_size + additional_extradata_size))) {
350 return AVERROR(ENOMEM);
351 }
352
353 3 avctx->extradata_size =
354 3 TTMLENC_EXTRADATA_SIGNATURE_SIZE + additional_extradata_size;
355 3 memcpy(avctx->extradata, TTMLENC_EXTRADATA_SIGNATURE,
356 TTMLENC_EXTRADATA_SIGNATURE_SIZE);
357
358
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3 if (additional_extradata_size)
359 3 memcpy(avctx->extradata + TTMLENC_EXTRADATA_SIGNATURE_SIZE,
360 3 s->buffer.str, additional_extradata_size);
361
362 3 av_bprint_clear(&s->buffer);
363
364 3 return 0;
365 }
366
367 3 static av_cold int ttml_encode_init(AVCodecContext *avctx)
368 {
369 3 TTMLContext *s = avctx->priv_data;
370 3 int ret = AVERROR_BUG;
371 3 s->avctx = avctx;
372
373 3 av_bprint_init(&s->buffer, 0, AV_BPRINT_SIZE_UNLIMITED);
374
375
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3 if (!(s->ass_ctx = ff_ass_split(avctx->subtitle_header))) {
376 return AVERROR_INVALIDDATA;
377 }
378
379
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3 if ((ret = ttml_write_header_content(avctx)) < 0) {
380 return ret;
381 }
382
383 3 return 0;
384 }
385
386 const AVCodec ff_ttml_encoder = {
387 .name = "ttml",
388 .long_name = NULL_IF_CONFIG_SMALL("TTML subtitle"),
389 .type = AVMEDIA_TYPE_SUBTITLE,
390 .id = AV_CODEC_ID_TTML,
391 .priv_data_size = sizeof(TTMLContext),
392 .init = ttml_encode_init,
393 .encode_sub = ttml_encode_frame,
394 .close = ttml_encode_close,
395 .caps_internal = FF_CODEC_CAP_INIT_THREADSAFE | FF_CODEC_CAP_INIT_CLEANUP,
396 };
397