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path: root/libavformat/srtdec.c (plain)
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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(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
214static int srt_read_packet(AVFormatContext *s, AVPacket *pkt)
215{
216 SRTContext *srt = s->priv_data;
217 return ff_subtitles_queue_read_packet(&srt->q, pkt);
218}
219
220static int srt_read_seek(AVFormatContext *s, int stream_index,
221 int64_t min_ts, int64_t ts, int64_t max_ts, int flags)
222{
223 SRTContext *srt = s->priv_data;
224 return ff_subtitles_queue_seek(&srt->q, s, stream_index,
225 min_ts, ts, max_ts, flags);
226}
227
228static int srt_read_close(AVFormatContext *s)
229{
230 SRTContext *srt = s->priv_data;
231 ff_subtitles_queue_clean(&srt->q);
232 return 0;
233}
234
235AVInputFormat ff_srt_demuxer = {
236 .name = "srt",
237 .long_name = NULL_IF_CONFIG_SMALL("SubRip subtitle"),
238 .priv_data_size = sizeof(SRTContext),
239 .read_probe = srt_probe,
240 .read_header = srt_read_header,
241 .read_packet = srt_read_packet,
242 .read_seek2 = srt_read_seek,
243 .read_close = srt_read_close,
244};
245
generated by cgit at 2024-05-17 06:30:05 (GMT)