| 1 | /* |
| 2 | * TED Talks captions format decoder |
| 3 | * Copyright (c) 2012 Nicolas George |
| 4 | * |
| 5 | * This file is part of FFmpeg. |
| 6 | * |
| 7 | * FFmpeg is free software; you can redistribute it and/or |
| 8 | * modify it under the terms of the GNU Lesser General Public |
| 9 | * License as published by the Free Software Foundation; either |
| 10 | * version 2.1 of the License, or (at your option) any later version. |
| 11 | * |
| 12 | * FFmpeg is distributed in the hope that it will be useful, |
| 13 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 14 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| 15 | * Lesser General Public License for more details. |
| 16 | * |
| 17 | * You should have received a copy of the GNU Lesser General Public |
| 18 | * License along with FFmpeg; if not, write to the Free Software |
| 19 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
| 20 | */ |
| 21 | |
| 22 | #include "libavutil/bprint.h" |
| 23 | #include "libavutil/log.h" |
| 24 | #include "libavutil/opt.h" |
| 25 | #include "avformat.h" |
| 26 | #include "internal.h" |
| 27 | #include "subtitles.h" |
| 28 | |
| 29 | typedef struct { |
| 30 | AVClass *class; |
| 31 | int64_t start_time; |
| 32 | FFDemuxSubtitlesQueue subs; |
| 33 | } TEDCaptionsDemuxer; |
| 34 | |
| 35 | static const AVOption tedcaptions_options[] = { |
| 36 | { "start_time", "set the start time (offset) of the subtitles, in ms", |
| 37 | offsetof(TEDCaptionsDemuxer, start_time), FF_OPT_TYPE_INT64, |
| 38 | { .i64 = 15000 }, INT64_MIN, INT64_MAX, |
| 39 | AV_OPT_FLAG_SUBTITLE_PARAM | AV_OPT_FLAG_DECODING_PARAM }, |
| 40 | { NULL }, |
| 41 | }; |
| 42 | |
| 43 | static const AVClass tedcaptions_demuxer_class = { |
| 44 | .class_name = "tedcaptions_demuxer", |
| 45 | .item_name = av_default_item_name, |
| 46 | .option = tedcaptions_options, |
| 47 | .version = LIBAVUTIL_VERSION_INT, |
| 48 | }; |
| 49 | |
| 50 | #define BETWEEN(a, amin, amax) ((unsigned)((a) - (amin)) <= (amax) - (amin)) |
| 51 | |
| 52 | #define HEX_DIGIT_TEST(c) (BETWEEN(c, '0', '9') || BETWEEN((c) | 32, 'a', 'z')) |
| 53 | #define HEX_DIGIT_VAL(c) ((c) <= '9' ? (c) - '0' : ((c) | 32) - 'a' + 10) |
| 54 | #define ERR_CODE(c) (c < 0 ? c : AVERROR_INVALIDDATA) |
| 55 | |
| 56 | static void av_bprint_utf8(AVBPrint *bp, unsigned c) |
| 57 | { |
| 58 | int bytes, i; |
| 59 | |
| 60 | if (c <= 0x7F) { |
| 61 | av_bprint_chars(bp, c, 1); |
| 62 | return; |
| 63 | } |
| 64 | bytes = (av_log2(c) - 2) / 5; |
| 65 | av_bprint_chars(bp, (c >> (bytes * 6)) | ((0xFF80 >> bytes) & 0xFF), 1); |
| 66 | for (i = bytes - 1; i >= 0; i--) |
| 67 | av_bprint_chars(bp, ((c >> (i * 6)) & 0x3F) | 0x80, 1); |
| 68 | } |
| 69 | |
| 70 | static void next_byte(AVIOContext *pb, int *cur_byte) |
| 71 | { |
| 72 | uint8_t b; |
| 73 | int ret = avio_read(pb, &b, 1); |
| 74 | *cur_byte = ret > 0 ? b : ret == 0 ? AVERROR_EOF : ret; |
| 75 | } |
| 76 | |
| 77 | static void skip_spaces(AVIOContext *pb, int *cur_byte) |
| 78 | { |
| 79 | while (*cur_byte == ' ' || *cur_byte == '\t' || |
| 80 | *cur_byte == '\n' || *cur_byte == '\r') |
| 81 | next_byte(pb, cur_byte); |
| 82 | } |
| 83 | |
| 84 | static int expect_byte(AVIOContext *pb, int *cur_byte, uint8_t c) |
| 85 | { |
| 86 | skip_spaces(pb, cur_byte); |
| 87 | if (*cur_byte != c) |
| 88 | return ERR_CODE(*cur_byte); |
| 89 | next_byte(pb, cur_byte); |
| 90 | return 0; |
| 91 | } |
| 92 | |
| 93 | static int parse_string(AVIOContext *pb, int *cur_byte, AVBPrint *bp, int full) |
| 94 | { |
| 95 | int ret; |
| 96 | |
| 97 | av_bprint_init(bp, 0, full ? -1 : 1); |
| 98 | ret = expect_byte(pb, cur_byte, '"'); |
| 99 | if (ret < 0) |
| 100 | goto fail; |
| 101 | while (*cur_byte > 0 && *cur_byte != '"') { |
| 102 | if (*cur_byte == '\\') { |
| 103 | next_byte(pb, cur_byte); |
| 104 | if (*cur_byte < 0) { |
| 105 | ret = AVERROR_INVALIDDATA; |
| 106 | goto fail; |
| 107 | } |
| 108 | if ((*cur_byte | 32) == 'u') { |
| 109 | unsigned chr = 0, i; |
| 110 | for (i = 0; i < 4; i++) { |
| 111 | next_byte(pb, cur_byte); |
| 112 | if (!HEX_DIGIT_TEST(*cur_byte)) { |
| 113 | ret = ERR_CODE(*cur_byte); |
| 114 | goto fail; |
| 115 | } |
| 116 | chr = chr * 16 + HEX_DIGIT_VAL(*cur_byte); |
| 117 | } |
| 118 | av_bprint_utf8(bp, chr); |
| 119 | } else { |
| 120 | av_bprint_chars(bp, *cur_byte, 1); |
| 121 | } |
| 122 | } else { |
| 123 | av_bprint_chars(bp, *cur_byte, 1); |
| 124 | } |
| 125 | next_byte(pb, cur_byte); |
| 126 | } |
| 127 | ret = expect_byte(pb, cur_byte, '"'); |
| 128 | if (ret < 0) |
| 129 | goto fail; |
| 130 | if (full && !av_bprint_is_complete(bp)) { |
| 131 | ret = AVERROR(ENOMEM); |
| 132 | goto fail; |
| 133 | } |
| 134 | return 0; |
| 135 | |
| 136 | fail: |
| 137 | av_bprint_finalize(bp, NULL); |
| 138 | return ret; |
| 139 | } |
| 140 | |
| 141 | static int parse_label(AVIOContext *pb, int *cur_byte, AVBPrint *bp) |
| 142 | { |
| 143 | int ret; |
| 144 | |
| 145 | ret = parse_string(pb, cur_byte, bp, 0); |
| 146 | if (ret < 0) |
| 147 | return ret; |
| 148 | ret = expect_byte(pb, cur_byte, ':'); |
| 149 | if (ret < 0) |
| 150 | return ret; |
| 151 | return 0; |
| 152 | } |
| 153 | |
| 154 | static int parse_boolean(AVIOContext *pb, int *cur_byte, int *result) |
| 155 | { |
| 156 | static const char * const text[] = { "false", "true" }; |
| 157 | const char *p; |
| 158 | int i; |
| 159 | |
| 160 | skip_spaces(pb, cur_byte); |
| 161 | for (i = 0; i < 2; i++) { |
| 162 | p = text[i]; |
| 163 | if (*cur_byte != *p) |
| 164 | continue; |
| 165 | for (; *p; p++, next_byte(pb, cur_byte)) |
| 166 | if (*cur_byte != *p) |
| 167 | return AVERROR_INVALIDDATA; |
| 168 | if (BETWEEN(*cur_byte | 32, 'a', 'z')) |
| 169 | return AVERROR_INVALIDDATA; |
| 170 | *result = i; |
| 171 | return 0; |
| 172 | } |
| 173 | return AVERROR_INVALIDDATA; |
| 174 | } |
| 175 | |
| 176 | static int parse_int(AVIOContext *pb, int *cur_byte, int64_t *result) |
| 177 | { |
| 178 | int64_t val = 0; |
| 179 | |
| 180 | skip_spaces(pb, cur_byte); |
| 181 | if ((unsigned)*cur_byte - '0' > 9) |
| 182 | return AVERROR_INVALIDDATA; |
| 183 | while (BETWEEN(*cur_byte, '0', '9')) { |
| 184 | val = val * 10 + (*cur_byte - '0'); |
| 185 | next_byte(pb, cur_byte); |
| 186 | } |
| 187 | *result = val; |
| 188 | return 0; |
| 189 | } |
| 190 | |
| 191 | static int parse_file(AVIOContext *pb, FFDemuxSubtitlesQueue *subs) |
| 192 | { |
| 193 | int ret, cur_byte, start_of_par; |
| 194 | AVBPrint label, content; |
| 195 | int64_t pos, start, duration; |
| 196 | AVPacket *pkt; |
| 197 | |
| 198 | next_byte(pb, &cur_byte); |
| 199 | ret = expect_byte(pb, &cur_byte, '{'); |
| 200 | if (ret < 0) |
| 201 | return AVERROR_INVALIDDATA; |
| 202 | ret = parse_label(pb, &cur_byte, &label); |
| 203 | if (ret < 0 || strcmp(label.str, "captions")) |
| 204 | return AVERROR_INVALIDDATA; |
| 205 | ret = expect_byte(pb, &cur_byte, '['); |
| 206 | if (ret < 0) |
| 207 | return AVERROR_INVALIDDATA; |
| 208 | while (1) { |
| 209 | content.size = 0; |
| 210 | start = duration = AV_NOPTS_VALUE; |
| 211 | ret = expect_byte(pb, &cur_byte, '{'); |
| 212 | if (ret < 0) |
| 213 | return ret; |
| 214 | pos = avio_tell(pb) - 1; |
| 215 | while (1) { |
| 216 | ret = parse_label(pb, &cur_byte, &label); |
| 217 | if (ret < 0) |
| 218 | return ret; |
| 219 | if (!strcmp(label.str, "startOfParagraph")) { |
| 220 | ret = parse_boolean(pb, &cur_byte, &start_of_par); |
| 221 | if (ret < 0) |
| 222 | return ret; |
| 223 | } else if (!strcmp(label.str, "content")) { |
| 224 | ret = parse_string(pb, &cur_byte, &content, 1); |
| 225 | if (ret < 0) |
| 226 | return ret; |
| 227 | } else if (!strcmp(label.str, "startTime")) { |
| 228 | ret = parse_int(pb, &cur_byte, &start); |
| 229 | if (ret < 0) |
| 230 | return ret; |
| 231 | } else if (!strcmp(label.str, "duration")) { |
| 232 | ret = parse_int(pb, &cur_byte, &duration); |
| 233 | if (ret < 0) |
| 234 | return ret; |
| 235 | } else { |
| 236 | return AVERROR_INVALIDDATA; |
| 237 | } |
| 238 | skip_spaces(pb, &cur_byte); |
| 239 | if (cur_byte != ',') |
| 240 | break; |
| 241 | next_byte(pb, &cur_byte); |
| 242 | } |
| 243 | ret = expect_byte(pb, &cur_byte, '}'); |
| 244 | if (ret < 0) |
| 245 | return ret; |
| 246 | |
| 247 | if (!content.size || start == AV_NOPTS_VALUE || |
| 248 | duration == AV_NOPTS_VALUE) |
| 249 | return AVERROR_INVALIDDATA; |
| 250 | pkt = ff_subtitles_queue_insert(subs, content.str, content.len, 0); |
| 251 | if (!pkt) |
| 252 | return AVERROR(ENOMEM); |
| 253 | pkt->pos = pos; |
| 254 | pkt->pts = start; |
| 255 | pkt->duration = duration; |
| 256 | av_bprint_finalize(&content, NULL); |
| 257 | |
| 258 | skip_spaces(pb, &cur_byte); |
| 259 | if (cur_byte != ',') |
| 260 | break; |
| 261 | next_byte(pb, &cur_byte); |
| 262 | } |
| 263 | ret = expect_byte(pb, &cur_byte, ']'); |
| 264 | if (ret < 0) |
| 265 | return ret; |
| 266 | ret = expect_byte(pb, &cur_byte, '}'); |
| 267 | if (ret < 0) |
| 268 | return ret; |
| 269 | skip_spaces(pb, &cur_byte); |
| 270 | if (cur_byte != AVERROR_EOF) |
| 271 | return ERR_CODE(cur_byte); |
| 272 | return 0; |
| 273 | } |
| 274 | |
| 275 | static av_cold int tedcaptions_read_header(AVFormatContext *avf) |
| 276 | { |
| 277 | TEDCaptionsDemuxer *tc = avf->priv_data; |
| 278 | AVStream *st; |
| 279 | int ret, i; |
| 280 | AVPacket *last; |
| 281 | |
| 282 | ret = parse_file(avf->pb, &tc->subs); |
| 283 | if (ret < 0) { |
| 284 | if (ret == AVERROR_INVALIDDATA) |
| 285 | av_log(avf, AV_LOG_ERROR, "Syntax error near offset %"PRId64".\n", |
| 286 | avio_tell(avf->pb)); |
| 287 | ff_subtitles_queue_clean(&tc->subs); |
| 288 | return ret; |
| 289 | } |
| 290 | ff_subtitles_queue_finalize(&tc->subs); |
| 291 | for (i = 0; i < tc->subs.nb_subs; i++) |
| 292 | tc->subs.subs[i].pts += tc->start_time; |
| 293 | |
| 294 | last = &tc->subs.subs[tc->subs.nb_subs - 1]; |
| 295 | st = avformat_new_stream(avf, NULL); |
| 296 | if (!st) |
| 297 | return AVERROR(ENOMEM); |
| 298 | st->codec->codec_type = AVMEDIA_TYPE_SUBTITLE; |
| 299 | st->codec->codec_id = AV_CODEC_ID_TEXT; |
| 300 | avpriv_set_pts_info(st, 64, 1, 1000); |
| 301 | st->probe_packets = 0; |
| 302 | st->start_time = 0; |
| 303 | st->duration = last->pts + last->duration; |
| 304 | st->cur_dts = 0; |
| 305 | |
| 306 | return 0; |
| 307 | } |
| 308 | |
| 309 | static int tedcaptions_read_packet(AVFormatContext *avf, AVPacket *packet) |
| 310 | { |
| 311 | TEDCaptionsDemuxer *tc = avf->priv_data; |
| 312 | |
| 313 | return ff_subtitles_queue_read_packet(&tc->subs, packet); |
| 314 | } |
| 315 | |
| 316 | static int tedcaptions_read_close(AVFormatContext *avf) |
| 317 | { |
| 318 | TEDCaptionsDemuxer *tc = avf->priv_data; |
| 319 | |
| 320 | ff_subtitles_queue_clean(&tc->subs); |
| 321 | return 0; |
| 322 | } |
| 323 | |
| 324 | static av_cold int tedcaptions_read_probe(AVProbeData *p) |
| 325 | { |
| 326 | static const char *const tags[] = { |
| 327 | "\"captions\"", "\"duration\"", "\"content\"", |
| 328 | "\"startOfParagraph\"", "\"startTime\"", |
| 329 | }; |
| 330 | unsigned i, count = 0; |
| 331 | const char *t; |
| 332 | |
| 333 | if (p->buf[strspn(p->buf, " \t\r\n")] != '{') |
| 334 | return 0; |
| 335 | for (i = 0; i < FF_ARRAY_ELEMS(tags); i++) { |
| 336 | if (!(t = strstr(p->buf, tags[i]))) |
| 337 | continue; |
| 338 | t += strlen(tags[i]); |
| 339 | t += strspn(t, " \t\r\n"); |
| 340 | if (*t == ':') |
| 341 | count++; |
| 342 | } |
| 343 | return count == FF_ARRAY_ELEMS(tags) ? AVPROBE_SCORE_MAX : |
| 344 | count ? AVPROBE_SCORE_EXTENSION : 0; |
| 345 | } |
| 346 | |
| 347 | static int tedcaptions_read_seek(AVFormatContext *avf, int stream_index, |
| 348 | int64_t min_ts, int64_t ts, int64_t max_ts, |
| 349 | int flags) |
| 350 | { |
| 351 | TEDCaptionsDemuxer *tc = avf->priv_data; |
| 352 | return ff_subtitles_queue_seek(&tc->subs, avf, stream_index, |
| 353 | min_ts, ts, max_ts, flags); |
| 354 | } |
| 355 | |
| 356 | AVInputFormat ff_tedcaptions_demuxer = { |
| 357 | .name = "tedcaptions", |
| 358 | .long_name = NULL_IF_CONFIG_SMALL("TED Talks captions"), |
| 359 | .priv_data_size = sizeof(TEDCaptionsDemuxer), |
| 360 | .priv_class = &tedcaptions_demuxer_class, |
| 361 | .read_header = tedcaptions_read_header, |
| 362 | .read_packet = tedcaptions_read_packet, |
| 363 | .read_close = tedcaptions_read_close, |
| 364 | .read_probe = tedcaptions_read_probe, |
| 365 | .read_seek2 = tedcaptions_read_seek, |
| 366 | }; |