| 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 | |
| 42 | static 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 | |
| 74 | static 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 | |
| 93 | AVCodec 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 | }; |