1/* 2 * SubRip subtitle demuxer 3 * Copyright (c) 2010 Aurelien Jacobs <aurel@gnuage.org> 4 * Copyright (c) 2015 Clément Bœsch <u pkh me> 5 * 6 * This file is part of FFmpeg. 7 * 8 * FFmpeg is free software; you can redistribute it and/or 9 * modify it under the terms of the GNU Lesser General Public 10 * License as published by the Free Software Foundation; either 11 * version 2.1 of the License, or (at your option) any later version. 12 * 13 * FFmpeg is distributed in the hope that it will be useful, 14 * but WITHOUT ANY WARRANTY; without even the implied warranty of 15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 16 * Lesser General Public License for more details. 17 * 18 * You should have received a copy of the GNU Lesser General Public 19 * License along with FFmpeg; if not, write to the Free Software 20 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA 21 */ 22 23#include "avformat.h" 24#include "internal.h" 25#include "subtitles.h" 26#include "libavutil/bprint.h" 27#include "libavutil/intreadwrite.h" 28 29typedef struct { 30 FFDemuxSubtitlesQueue q; 31} SRTContext; 32 33static int srt_probe(const AVProbeData *p) 34{ 35 int v; 36 char buf[64], *pbuf; 37 FFTextReader tr; 38 39 ff_text_init_buf(&tr, p->buf, p->buf_size); 40 41 while (ff_text_peek_r8(&tr) == '\r' || ff_text_peek_r8(&tr) == '\n') 42 ff_text_r8(&tr); 43 44 /* Check if the first non-empty line is a number. We do not check what the 45 * number is because in practice it can be anything. 46 * Also, that number can be followed by random garbage, so we can not 47 * unfortunately check that we only have a number. */ 48 if (ff_subtitles_read_line(&tr, buf, sizeof(buf)) < 0 || 49 strtol(buf, &pbuf, 10) < 0 || pbuf == buf) 50 return 0; 51 52 /* Check if the next line matches a SRT timestamp */ 53 if (ff_subtitles_read_line(&tr, buf, sizeof(buf)) < 0) 54 return 0; 55 pbuf = buf; 56 if (buf[0] == '-') 57 pbuf++; 58 if (pbuf[0] >= '0' && pbuf[0] <= '9' && strstr(buf, " --> ") 59 && sscanf(buf, "%*d:%*d:%*d%*1[,.]%*d --> %*d:%*d:%*d%*1[,.]%d", &v) == 1) 60 return AVPROBE_SCORE_MAX; 61 62 return 0; 63} 64 65struct event_info { 66 int32_t x1, x2, y1, y2; 67 int duration; 68 int64_t pts; 69 int64_t pos; 70}; 71 72static int get_event_info(const char *line, struct event_info *ei) 73{ 74 int hh1, mm1, ss1, ms1; 75 int hh2, mm2, ss2, ms2; 76 77 ei->x1 = ei->x2 = ei->y1 = ei->y2 = ei->duration = -1; 78 ei->pts = AV_NOPTS_VALUE; 79 ei->pos = -1; 80 if (sscanf(line, "%d:%d:%d%*1[,.]%d --> %d:%d:%d%*1[,.]%d" 81 "%*[ ]X1:%"PRId32" X2:%"PRId32" Y1:%"PRId32" Y2:%"PRId32, 82 &hh1, &mm1, &ss1, &ms1, 83 &hh2, &mm2, &ss2, &ms2, 84 &ei->x1, &ei->x2, &ei->y1, &ei->y2) >= 8) { 85 const int64_t start = (hh1*3600LL + mm1*60LL + ss1) * 1000LL + ms1; 86 const int64_t end = (hh2*3600LL + mm2*60LL + ss2) * 1000LL + ms2; 87 ei->duration = end - start; 88 ei->pts = start; 89 return 0; 90 } 91 return -1; 92} 93 94static int add_event(FFDemuxSubtitlesQueue *q, AVBPrint *buf, char *line_cache, 95 const struct event_info *ei, int append_cache) 96{ 97 if (append_cache && line_cache[0]) 98 av_bprintf(buf, "%s\n", line_cache); 99 line_cache[0] = 0; 100 101 while (buf->len > 0 && buf->str[buf->len - 1] == '\n') 102 buf->str[--buf->len] = 0; 103 104 if (buf->len) { 105 AVPacket *sub = ff_subtitles_queue_insert(q, buf->str, buf->len, 0); 106 if (!sub) 107 return AVERROR(ENOMEM); 108 av_bprint_clear(buf); 109 sub->pos = ei->pos; 110 sub->pts = ei->pts; 111 sub->duration = ei->duration; 112 if (ei->x1 != -1) { 113 uint8_t *p = av_packet_new_side_data(sub, AV_PKT_DATA_SUBTITLE_POSITION, 16); 114 if (p) { 115 AV_WL32(p, ei->x1); 116 AV_WL32(p + 4, ei->y1); 117 AV_WL32(p + 8, ei->x2); 118 AV_WL32(p + 12, ei->y2); 119 } 120 } 121 } 122 123 return 0; 124} 125 126static int srt_read_header(AVFormatContext *s) 127{ 128 SRTContext *srt = s->priv_data; 129 AVBPrint buf; 130 AVStream *st = avformat_new_stream(s, NULL); 131 int res = 0; 132 char line[4096], line_cache[4096]; 133 int has_event_info = 0; 134 struct event_info ei; 135 FFTextReader tr; 136 ff_text_init_avio(s, &tr, s->pb); 137 138 if (!st) 139 return AVERROR(ENOMEM); 140 avpriv_set_pts_info(st, 64, 1, 1000); 141 st->codecpar->codec_type = AVMEDIA_TYPE_SUBTITLE; 142 st->codecpar->codec_id = AV_CODEC_ID_SUBRIP; 143 144 av_bprint_init(&buf, 0, AV_BPRINT_SIZE_UNLIMITED); 145 146 line_cache[0] = 0; 147 148 while (!ff_text_eof(&tr)) { 149 struct event_info tmp_ei; 150 const int64_t pos = ff_text_pos(&tr); 151 ptrdiff_t len = ff_subtitles_read_line(&tr, line, sizeof(line)); 152 153 if (len < 0) 154 break; 155 156 if (!len || !line[0]) 157 continue; 158 159 if (get_event_info(line, &tmp_ei) < 0) { 160 char *pline; 161 162 if (!has_event_info) 163 continue; 164 165 if (line_cache[0]) { 166 /* We got some cache and a new line so we assume the cached 167 * line was actually part of the payload */ 168 av_bprintf(&buf, "%s\n", line_cache); 169 line_cache[0] = 0; 170 } 171 172 /* If the line doesn't start with a number, we assume it's part of 173 * the payload, otherwise is likely an event number preceding the 174 * timing information... but we can't be sure of this yet, so we 175 * cache it */ 176 if (strtol(line, &pline, 10) < 0 || line == pline) 177 av_bprintf(&buf, "%s\n", line); 178 else 179 strcpy(line_cache, line); 180 } else { 181 if (has_event_info) { 182 /* We have the information of previous event, append it to the 183 * queue. We insert the cached line if and only if the payload 184 * is empty and the cached line is not a standalone number. */ 185 char *pline = NULL; 186 const int standalone_number = strtol(line_cache, &pline, 10) >= 0 && pline && !*pline; 187 res = add_event(&srt->q, &buf, line_cache, &ei, !buf.len && !standalone_number); 188 if (res < 0) 189 goto end; 190 } else { 191 has_event_info = 1; 192 } 193 tmp_ei.pos = pos; 194 ei = tmp_ei; 195 } 196 } 197 198 /* Append the last event. Here we force the cache to be flushed, because a 199 * trailing number is more likely to be geniune (for example a copyright 200 * date) and not the event index of an inexistant event */ 201 if (has_event_info) { 202 res = add_event(&srt->q, &buf, line_cache, &ei, 1); 203 if (res < 0) 204 goto end; 205 } 206 207 ff_subtitles_queue_finalize(s, &srt->q); 208 209end: 210 av_bprint_finalize(&buf, NULL); 211 return res; 212} 213 214const AVInputFormat ff_srt_demuxer = { 215 .name = "srt", 216 .long_name = NULL_IF_CONFIG_SMALL("SubRip subtitle"), 217 .priv_data_size = sizeof(SRTContext), 218 .flags_internal = FF_FMT_INIT_CLEANUP, 219 .read_probe = srt_probe, 220 .read_header = srt_read_header, 221 .read_packet = ff_subtitles_read_packet, 222 .read_seek2 = ff_subtitles_read_seek, 223 .read_close = ff_subtitles_read_close, 224}; 225