| 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 demuxer |
| 24 | * @see http://dev.w3.org/html5/webvtt/ |
| 25 | */ |
| 26 | |
| 27 | #include "avformat.h" |
| 28 | #include "internal.h" |
| 29 | #include "subtitles.h" |
| 30 | #include "libavutil/bprint.h" |
| 31 | #include "libavutil/intreadwrite.h" |
| 32 | #include "libavutil/opt.h" |
| 33 | |
| 34 | typedef struct { |
| 35 | const AVClass *class; |
| 36 | FFDemuxSubtitlesQueue q; |
| 37 | int kind; |
| 38 | } WebVTTContext; |
| 39 | |
| 40 | static int webvtt_probe(AVProbeData *p) |
| 41 | { |
| 42 | const uint8_t *ptr = p->buf; |
| 43 | |
| 44 | if (AV_RB24(ptr) == 0xEFBBBF) |
| 45 | ptr += 3; /* skip UTF-8 BOM */ |
| 46 | if (!strncmp(ptr, "WEBVTT", 6) && |
| 47 | (!ptr[6] || strchr("\n\r\t ", ptr[6]))) |
| 48 | return AVPROBE_SCORE_MAX; |
| 49 | return 0; |
| 50 | } |
| 51 | |
| 52 | static int64_t read_ts(const char *s) |
| 53 | { |
| 54 | int hh, mm, ss, ms; |
| 55 | if (sscanf(s, "%u:%u:%u.%u", &hh, &mm, &ss, &ms) == 4) return (hh*3600LL + mm*60LL + ss) * 1000LL + ms; |
| 56 | if (sscanf(s, "%u:%u.%u", &mm, &ss, &ms) == 3) return ( mm*60LL + ss) * 1000LL + ms; |
| 57 | return AV_NOPTS_VALUE; |
| 58 | } |
| 59 | |
| 60 | static int webvtt_read_header(AVFormatContext *s) |
| 61 | { |
| 62 | WebVTTContext *webvtt = s->priv_data; |
| 63 | AVBPrint header, cue; |
| 64 | int res = 0; |
| 65 | AVStream *st = avformat_new_stream(s, NULL); |
| 66 | |
| 67 | if (!st) |
| 68 | return AVERROR(ENOMEM); |
| 69 | avpriv_set_pts_info(st, 64, 1, 1000); |
| 70 | st->codec->codec_type = AVMEDIA_TYPE_SUBTITLE; |
| 71 | st->codec->codec_id = AV_CODEC_ID_WEBVTT; |
| 72 | st->disposition |= webvtt->kind; |
| 73 | |
| 74 | av_bprint_init(&header, 0, AV_BPRINT_SIZE_UNLIMITED); |
| 75 | av_bprint_init(&cue, 0, AV_BPRINT_SIZE_UNLIMITED); |
| 76 | |
| 77 | for (;;) { |
| 78 | int i; |
| 79 | int64_t pos; |
| 80 | AVPacket *sub; |
| 81 | const char *p, *identifier, *settings; |
| 82 | int identifier_len, settings_len; |
| 83 | int64_t ts_start, ts_end; |
| 84 | |
| 85 | ff_subtitles_read_chunk(s->pb, &cue); |
| 86 | |
| 87 | if (!cue.len) |
| 88 | break; |
| 89 | |
| 90 | p = identifier = cue.str; |
| 91 | pos = avio_tell(s->pb); |
| 92 | |
| 93 | /* ignore header chunk */ |
| 94 | if (!strncmp(p, "\xEF\xBB\xBFWEBVTT", 9) || |
| 95 | !strncmp(p, "WEBVTT", 6)) |
| 96 | continue; |
| 97 | |
| 98 | /* optional cue identifier (can be a number like in SRT or some kind of |
| 99 | * chaptering id) */ |
| 100 | for (i = 0; p[i] && p[i] != '\n' && p[i] != '\r'; i++) { |
| 101 | if (!strncmp(p + i, "-->", 3)) { |
| 102 | identifier = NULL; |
| 103 | break; |
| 104 | } |
| 105 | } |
| 106 | if (!identifier) |
| 107 | identifier_len = 0; |
| 108 | else { |
| 109 | identifier_len = strcspn(p, "\r\n"); |
| 110 | p += identifier_len; |
| 111 | if (*p == '\r') |
| 112 | p++; |
| 113 | if (*p == '\n') |
| 114 | p++; |
| 115 | } |
| 116 | |
| 117 | /* cue timestamps */ |
| 118 | if ((ts_start = read_ts(p)) == AV_NOPTS_VALUE) |
| 119 | break; |
| 120 | if (!(p = strstr(p, "-->"))) |
| 121 | break; |
| 122 | p += 2; |
| 123 | do p++; while (*p == ' ' || *p == '\t'); |
| 124 | if ((ts_end = read_ts(p)) == AV_NOPTS_VALUE) |
| 125 | break; |
| 126 | |
| 127 | /* optional cue settings */ |
| 128 | p += strcspn(p, "\n\t "); |
| 129 | while (*p == '\t' || *p == ' ') |
| 130 | p++; |
| 131 | settings = p; |
| 132 | settings_len = strcspn(p, "\r\n"); |
| 133 | p += settings_len; |
| 134 | if (*p == '\r') |
| 135 | p++; |
| 136 | if (*p == '\n') |
| 137 | p++; |
| 138 | |
| 139 | /* create packet */ |
| 140 | sub = ff_subtitles_queue_insert(&webvtt->q, p, strlen(p), 0); |
| 141 | if (!sub) { |
| 142 | res = AVERROR(ENOMEM); |
| 143 | goto end; |
| 144 | } |
| 145 | sub->pos = pos; |
| 146 | sub->pts = ts_start; |
| 147 | sub->duration = ts_end - ts_start; |
| 148 | |
| 149 | #define SET_SIDE_DATA(name, type) do { \ |
| 150 | if (name##_len) { \ |
| 151 | uint8_t *buf = av_packet_new_side_data(sub, type, name##_len); \ |
| 152 | if (!buf) { \ |
| 153 | res = AVERROR(ENOMEM); \ |
| 154 | goto end; \ |
| 155 | } \ |
| 156 | memcpy(buf, name, name##_len); \ |
| 157 | } \ |
| 158 | } while (0) |
| 159 | |
| 160 | SET_SIDE_DATA(identifier, AV_PKT_DATA_WEBVTT_IDENTIFIER); |
| 161 | SET_SIDE_DATA(settings, AV_PKT_DATA_WEBVTT_SETTINGS); |
| 162 | } |
| 163 | |
| 164 | ff_subtitles_queue_finalize(&webvtt->q); |
| 165 | |
| 166 | end: |
| 167 | av_bprint_finalize(&cue, NULL); |
| 168 | av_bprint_finalize(&header, NULL); |
| 169 | return res; |
| 170 | } |
| 171 | |
| 172 | static int webvtt_read_packet(AVFormatContext *s, AVPacket *pkt) |
| 173 | { |
| 174 | WebVTTContext *webvtt = s->priv_data; |
| 175 | return ff_subtitles_queue_read_packet(&webvtt->q, pkt); |
| 176 | } |
| 177 | |
| 178 | static int webvtt_read_seek(AVFormatContext *s, int stream_index, |
| 179 | int64_t min_ts, int64_t ts, int64_t max_ts, int flags) |
| 180 | { |
| 181 | WebVTTContext *webvtt = s->priv_data; |
| 182 | return ff_subtitles_queue_seek(&webvtt->q, s, stream_index, |
| 183 | min_ts, ts, max_ts, flags); |
| 184 | } |
| 185 | |
| 186 | static int webvtt_read_close(AVFormatContext *s) |
| 187 | { |
| 188 | WebVTTContext *webvtt = s->priv_data; |
| 189 | ff_subtitles_queue_clean(&webvtt->q); |
| 190 | return 0; |
| 191 | } |
| 192 | |
| 193 | #define OFFSET(x) offsetof(WebVTTContext, x) |
| 194 | #define KIND_FLAGS AV_OPT_FLAG_SUBTITLE_PARAM |
| 195 | |
| 196 | static const AVOption options[] = { |
| 197 | { "kind", "Set kind of WebVTT track", OFFSET(kind), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, INT_MAX, KIND_FLAGS, "webvtt_kind" }, |
| 198 | { "subtitles", "WebVTT subtitles kind", 0, AV_OPT_TYPE_CONST, { .i64 = 0 }, INT_MIN, INT_MAX, 0, "webvtt_kind" }, |
| 199 | { "captions", "WebVTT captions kind", 0, AV_OPT_TYPE_CONST, { .i64 = AV_DISPOSITION_CAPTIONS }, INT_MIN, INT_MAX, 0, "webvtt_kind" }, |
| 200 | { "descriptions", "WebVTT descriptions kind", 0, AV_OPT_TYPE_CONST, { .i64 = AV_DISPOSITION_DESCRIPTIONS }, INT_MIN, INT_MAX, 0, "webvtt_kind" }, |
| 201 | { "metadata", "WebVTT metadata kind", 0, AV_OPT_TYPE_CONST, { .i64 = AV_DISPOSITION_METADATA }, INT_MIN, INT_MAX, 0, "webvtt_kind" }, |
| 202 | { NULL } |
| 203 | }; |
| 204 | |
| 205 | static const AVClass webvtt_demuxer_class = { |
| 206 | .class_name = "WebVTT demuxer", |
| 207 | .item_name = av_default_item_name, |
| 208 | .option = options, |
| 209 | .version = LIBAVUTIL_VERSION_INT, |
| 210 | }; |
| 211 | |
| 212 | AVInputFormat ff_webvtt_demuxer = { |
| 213 | .name = "webvtt", |
| 214 | .long_name = NULL_IF_CONFIG_SMALL("WebVTT subtitle"), |
| 215 | .priv_data_size = sizeof(WebVTTContext), |
| 216 | .read_probe = webvtt_probe, |
| 217 | .read_header = webvtt_read_header, |
| 218 | .read_packet = webvtt_read_packet, |
| 219 | .read_seek2 = webvtt_read_seek, |
| 220 | .read_close = webvtt_read_close, |
| 221 | .extensions = "vtt", |
| 222 | .priv_class = &webvtt_demuxer_class, |
| 223 | }; |