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 29typedef struct { 30 AVClass *class; 31 int64_t start_time; 32 FFDemuxSubtitlesQueue subs; 33} TEDCaptionsDemuxer; 34 35static 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 43static 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 56static 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 70static 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 77static 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 84static 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 93static 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 136fail: 137 av_bprint_finalize(bp, NULL); 138 return ret; 139} 140 141static 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 154static 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 176static 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 191static 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 275static 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 309static 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 316static 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 324static 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 347static 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 356AVInputFormat 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}; 367