FFmpeg coverage


Directory: ../../../ffmpeg/
File: src/libavcodec/ttmlenc.c
Date: 2024-03-29 11:55:30
Exec Total Coverage
Lines: 130 178 73.0%
Functions: 11 11 100.0%
Branches: 31 68 45.6%

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