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
ttml_text_cb(void * priv,const char * text,int len)45 static void ttml_text_cb(void *priv, const char *text, int len)
46 {
47 TTMLContext *s = priv;
48 AVBPrint cur_line = { 0 };
49 AVBPrint *buffer = &s->buffer;
50
51 av_bprint_init(&cur_line, len, AV_BPRINT_SIZE_UNLIMITED);
52
53 av_bprint_append_data(&cur_line, text, len);
54 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 av_bprint_escape(buffer, cur_line.str, NULL, AV_ESCAPE_MODE_XML,
63 0);
64
65 av_bprint_finalize(&cur_line, NULL);
66 }
67
ttml_new_line_cb(void * priv,int forced)68 static void ttml_new_line_cb(void *priv, int forced)
69 {
70 TTMLContext *s = priv;
71
72 av_bprintf(&s->buffer, "<br/>");
73 }
74
75 static const ASSCodesCallbacks ttml_callbacks = {
76 .text = ttml_text_cb,
77 .new_line = ttml_new_line_cb,
78 };
79
ttml_encode_frame(AVCodecContext * avctx,uint8_t * buf,int bufsize,const AVSubtitle * sub)80 static int ttml_encode_frame(AVCodecContext *avctx, uint8_t *buf,
81 int bufsize, const AVSubtitle *sub)
82 {
83 TTMLContext *s = avctx->priv_data;
84 ASSDialog *dialog;
85 int i;
86
87 av_bprint_clear(&s->buffer);
88
89 for (i=0; i<sub->num_rects; i++) {
90 const char *ass = sub->rects[i]->ass;
91
92 if (sub->rects[i]->type != SUBTITLE_ASS) {
93 av_log(avctx, AV_LOG_ERROR, "Only SUBTITLE_ASS type supported.\n");
94 return AVERROR(EINVAL);
95 }
96
97 #if FF_API_ASS_TIMING
98 if (!strncmp(ass, "Dialogue: ", 10)) {
99 int num;
100 dialog = ff_ass_split_dialog(s->ass_ctx, ass, 0, &num);
101
102 for (; dialog && num--; dialog++) {
103 int ret = ff_ass_split_override_codes(&ttml_callbacks, s,
104 dialog->text);
105 int log_level = (ret != AVERROR_INVALIDDATA ||
106 avctx->err_recognition & AV_EF_EXPLODE) ?
107 AV_LOG_ERROR : AV_LOG_WARNING;
108
109 if (ret < 0) {
110 av_log(avctx, log_level,
111 "Splitting received ASS dialog failed: %s\n",
112 av_err2str(ret));
113
114 if (log_level == AV_LOG_ERROR)
115 return ret;
116 }
117 }
118 } else {
119 #endif
120 dialog = ff_ass_split_dialog2(s->ass_ctx, ass);
121 if (!dialog)
122 return AVERROR(ENOMEM);
123
124 {
125 int ret = ff_ass_split_override_codes(&ttml_callbacks, s,
126 dialog->text);
127 int log_level = (ret != AVERROR_INVALIDDATA ||
128 avctx->err_recognition & AV_EF_EXPLODE) ?
129 AV_LOG_ERROR : AV_LOG_WARNING;
130
131 if (ret < 0) {
132 av_log(avctx, log_level,
133 "Splitting received ASS dialog text %s failed: %s\n",
134 dialog->text,
135 av_err2str(ret));
136
137 if (log_level == AV_LOG_ERROR) {
138 ff_ass_free_dialog(&dialog);
139 return ret;
140 }
141 }
142
143 ff_ass_free_dialog(&dialog);
144 }
145 #if FF_API_ASS_TIMING
146 }
147 #endif
148 }
149
150 if (!av_bprint_is_complete(&s->buffer))
151 return AVERROR(ENOMEM);
152 if (!s->buffer.len)
153 return 0;
154
155 // force null-termination, so in case our destination buffer is
156 // too small, the return value is larger than bufsize minus null.
157 if (av_strlcpy(buf, s->buffer.str, bufsize) > bufsize - 1) {
158 av_log(avctx, AV_LOG_ERROR, "Buffer too small for TTML event.\n");
159 return AVERROR_BUFFER_TOO_SMALL;
160 }
161
162 return s->buffer.len;
163 }
164
ttml_encode_close(AVCodecContext * avctx)165 static av_cold int ttml_encode_close(AVCodecContext *avctx)
166 {
167 TTMLContext *s = avctx->priv_data;
168
169 ff_ass_split_free(s->ass_ctx);
170
171 av_bprint_finalize(&s->buffer, NULL);
172
173 return 0;
174 }
175
ttml_encode_init(AVCodecContext * avctx)176 static av_cold int ttml_encode_init(AVCodecContext *avctx)
177 {
178 TTMLContext *s = avctx->priv_data;
179
180 s->avctx = avctx;
181
182 if (!(s->ass_ctx = ff_ass_split(avctx->subtitle_header))) {
183 return AVERROR_INVALIDDATA;
184 }
185
186 if (!(avctx->extradata = av_mallocz(TTMLENC_EXTRADATA_SIGNATURE_SIZE +
187 1 + AV_INPUT_BUFFER_PADDING_SIZE))) {
188 return AVERROR(ENOMEM);
189 }
190
191 avctx->extradata_size = TTMLENC_EXTRADATA_SIGNATURE_SIZE;
192 memcpy(avctx->extradata, TTMLENC_EXTRADATA_SIGNATURE,
193 TTMLENC_EXTRADATA_SIGNATURE_SIZE);
194
195 av_bprint_init(&s->buffer, 0, AV_BPRINT_SIZE_UNLIMITED);
196
197 return 0;
198 }
199
200 AVCodec ff_ttml_encoder = {
201 .name = "ttml",
202 .long_name = NULL_IF_CONFIG_SMALL("TTML subtitle"),
203 .type = AVMEDIA_TYPE_SUBTITLE,
204 .id = AV_CODEC_ID_TTML,
205 .priv_data_size = sizeof(TTMLContext),
206 .init = ttml_encode_init,
207 .encode_sub = ttml_encode_frame,
208 .close = ttml_encode_close,
209 .capabilities = FF_CODEC_CAP_INIT_CLEANUP,
210 };
211