1 /*
2 * Copyright (c) 2012 Clément Bœsch
3 *
4 * This file is part of FFmpeg.
5 *
6 * FFmpeg is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU Lesser General Public
8 * License as published by the Free Software Foundation; either
9 * version 2.1 of the License, or (at your option) any later version.
10 *
11 * FFmpeg is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 * Lesser General Public License for more details.
15 *
16 * You should have received a copy of the GNU Lesser General Public
17 * License along with FFmpeg; if not, write to the Free Software
18 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19 */
20
21 /**
22 * @file
23 * WebVTT subtitle decoder
24 * @see http://dev.w3.org/html5/webvtt/
25 * @todo need to support extended markups and cue settings
26 */
27
28 #include "avcodec.h"
29 #include "ass.h"
30 #include "libavutil/bprint.h"
31
32 static const struct {
33 const char *from;
34 const char *to;
35 } webvtt_tag_replace[] = {
36 {"<i>", "{\\i1}"}, {"</i>", "{\\i0}"},
37 {"<b>", "{\\b1}"}, {"</b>", "{\\b0}"},
38 {"<u>", "{\\u1}"}, {"</u>", "{\\u0}"},
39 {"{", "\\{"}, {"}", "\\}"}, // escape to avoid ASS markup conflicts
40 {">", ">"}, {"<", "<"},
41 {"‎", ""}, {"‏", ""}, // FIXME: properly honor bidi marks
42 {"&", "&"}, {" ", "\\h"},
43 };
44
webvtt_event_to_ass(AVBPrint * buf,const char * p)45 static int webvtt_event_to_ass(AVBPrint *buf, const char *p)
46 {
47 int i, again = 0, skip = 0;
48
49 while (*p) {
50
51 for (i = 0; i < FF_ARRAY_ELEMS(webvtt_tag_replace); i++) {
52 const char *from = webvtt_tag_replace[i].from;
53 const size_t len = strlen(from);
54 if (!strncmp(p, from, len)) {
55 av_bprintf(buf, "%s", webvtt_tag_replace[i].to);
56 p += len;
57 again = 1;
58 break;
59 }
60 }
61 if (!*p)
62 break;
63
64 if (again) {
65 again = 0;
66 skip = 0;
67 continue;
68 }
69 if (*p == '<')
70 skip = 1;
71 else if (*p == '>')
72 skip = 0;
73 else if (p[0] == '\n' && p[1])
74 av_bprintf(buf, "\\N");
75 else if (!skip && *p != '\r')
76 av_bprint_chars(buf, *p, 1);
77 p++;
78 }
79 return 0;
80 }
81
webvtt_decode_frame(AVCodecContext * avctx,void * data,int * got_sub_ptr,AVPacket * avpkt)82 static int webvtt_decode_frame(AVCodecContext *avctx,
83 void *data, int *got_sub_ptr, AVPacket *avpkt)
84 {
85 int ret = 0;
86 AVSubtitle *sub = data;
87 const char *ptr = avpkt->data;
88 FFASSDecoderContext *s = avctx->priv_data;
89 AVBPrint buf;
90
91 av_bprint_init(&buf, 0, AV_BPRINT_SIZE_UNLIMITED);
92 if (ptr && avpkt->size > 0 && !webvtt_event_to_ass(&buf, ptr))
93 ret = ff_ass_add_rect(sub, buf.str, s->readorder++, 0, NULL, NULL);
94 av_bprint_finalize(&buf, NULL);
95 if (ret < 0)
96 return ret;
97 *got_sub_ptr = sub->num_rects > 0;
98 return avpkt->size;
99 }
100
101 AVCodec ff_webvtt_decoder = {
102 .name = "webvtt",
103 .long_name = NULL_IF_CONFIG_SMALL("WebVTT subtitle"),
104 .type = AVMEDIA_TYPE_SUBTITLE,
105 .id = AV_CODEC_ID_WEBVTT,
106 .decode = webvtt_decode_frame,
107 .init = ff_ass_subtitle_header_default,
108 .flush = ff_ass_decoder_flush,
109 .priv_data_size = sizeof(FFASSDecoderContext),
110 };
111