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 "codec_internal.h"
31 #include "libavutil/bprint.h"
32
33 static const struct {
34 const char *from;
35 const char *to;
36 } webvtt_tag_replace[] = {
37 {"<i>", "{\\i1}"}, {"</i>", "{\\i0}"},
38 {"<b>", "{\\b1}"}, {"</b>", "{\\b0}"},
39 {"<u>", "{\\u1}"}, {"</u>", "{\\u0}"},
40 {"{", "\\{"}, {"}", "\\}"}, // escape to avoid ASS markup conflicts
41 {">", ">"}, {"<", "<"},
42 {"‎", ""}, {"‏", ""}, // FIXME: properly honor bidi marks
43 {"&", "&"}, {" ", "\\h"},
44 };
45
webvtt_event_to_ass(AVBPrint * buf,const char * p)46 static int webvtt_event_to_ass(AVBPrint *buf, const char *p)
47 {
48 int i, again = 0, skip = 0;
49
50 while (*p) {
51
52 for (i = 0; i < FF_ARRAY_ELEMS(webvtt_tag_replace); i++) {
53 const char *from = webvtt_tag_replace[i].from;
54 const size_t len = strlen(from);
55 if (!strncmp(p, from, len)) {
56 av_bprintf(buf, "%s", webvtt_tag_replace[i].to);
57 p += len;
58 again = 1;
59 break;
60 }
61 }
62 if (!*p)
63 break;
64
65 if (again) {
66 again = 0;
67 skip = 0;
68 continue;
69 }
70 if (*p == '<')
71 skip = 1;
72 else if (*p == '>')
73 skip = 0;
74 else if (p[0] == '\n' && p[1])
75 av_bprintf(buf, "\\N");
76 else if (!skip && *p != '\r')
77 av_bprint_chars(buf, *p, 1);
78 p++;
79 }
80 return 0;
81 }
82
webvtt_decode_frame(AVCodecContext * avctx,AVSubtitle * sub,int * got_sub_ptr,const AVPacket * avpkt)83 static int webvtt_decode_frame(AVCodecContext *avctx, AVSubtitle *sub,
84 int *got_sub_ptr, const AVPacket *avpkt)
85 {
86 int ret = 0;
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 const FFCodec ff_webvtt_decoder = {
102 .p.name = "webvtt",
103 .p.long_name = NULL_IF_CONFIG_SMALL("WebVTT subtitle"),
104 .p.type = AVMEDIA_TYPE_SUBTITLE,
105 .p.id = AV_CODEC_ID_WEBVTT,
106 FF_CODEC_DECODE_SUB_CB(webvtt_decode_frame),
107 .init = ff_ass_subtitle_header_default,
108 .flush = ff_ass_decoder_flush,
109 .priv_data_size = sizeof(FFASSDecoderContext),
110 .caps_internal = FF_CODEC_CAP_INIT_THREADSAFE,
111 };
112