1/*
2 * Copyright (c) 2012 Cl��ment B��sch
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
32static 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
42static int webvtt_event_to_ass(AVBPrint *buf, const char *p)
43{
44    int i, skip = 0;
45
46    while (*p) {
47
48        for (i = 0; i < FF_ARRAY_ELEMS(webvtt_tag_replace); i++) {
49            const char *from = webvtt_tag_replace[i].from;
50            const size_t len = strlen(from);
51            if (!strncmp(p, from, len)) {
52                av_bprintf(buf, "%s", webvtt_tag_replace[i].to);
53                p += len;
54                break;
55            }
56        }
57        if (!*p)
58            break;
59
60        if (*p == '<')
61            skip = 1;
62        else if (*p == '>')
63            skip = 0;
64        else if (p[0] == '\n' && p[1])
65            av_bprintf(buf, "\\N");
66        else if (!skip && *p != '\r')
67            av_bprint_chars(buf, *p, 1);
68        p++;
69    }
70    av_bprintf(buf, "\r\n");
71    return 0;
72}
73
74static int webvtt_decode_frame(AVCodecContext *avctx,
75                               void *data, int *got_sub_ptr, AVPacket *avpkt)
76{
77    AVSubtitle *sub = data;
78    const char *ptr = avpkt->data;
79    AVBPrint buf;
80
81    av_bprint_init(&buf, 0, AV_BPRINT_SIZE_UNLIMITED);
82    if (ptr && avpkt->size > 0 && !webvtt_event_to_ass(&buf, ptr)) {
83        int ts_start     = av_rescale_q(avpkt->pts, avctx->time_base, (AVRational){1,100});
84        int ts_duration  = avpkt->duration != -1 ?
85                           av_rescale_q(avpkt->duration, avctx->time_base, (AVRational){1,100}) : -1;
86        ff_ass_add_rect(sub, buf.str, ts_start, ts_duration, 0);
87    }
88    *got_sub_ptr = sub->num_rects > 0;
89    av_bprint_finalize(&buf, NULL);
90    return avpkt->size;
91}
92
93AVCodec ff_webvtt_decoder = {
94    .name           = "webvtt",
95    .long_name      = NULL_IF_CONFIG_SMALL("WebVTT subtitle"),
96    .type           = AVMEDIA_TYPE_SUBTITLE,
97    .id             = AV_CODEC_ID_WEBVTT,
98    .decode         = webvtt_decode_frame,
99    .init           = ff_ass_subtitle_header_default,
100};
101