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path: root/libavformat/webvttdec.c (plain)
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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
34typedef struct {
35 const AVClass *class;
36 FFDemuxSubtitlesQueue q;
37 int kind;
38} WebVTTContext;
39
40static 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
52static 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
60static 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->codecpar->codec_type = AVMEDIA_TYPE_SUBTITLE;
71 st->codecpar->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 !strncmp(p, "NOTE", 4))
97 continue;
98
99 /* optional cue identifier (can be a number like in SRT or some kind of
100 * chaptering id) */
101 for (i = 0; p[i] && p[i] != '\n' && p[i] != '\r'; i++) {
102 if (!strncmp(p + i, "-->", 3)) {
103 identifier = NULL;
104 break;
105 }
106 }
107 if (!identifier)
108 identifier_len = 0;
109 else {
110 identifier_len = strcspn(p, "\r\n");
111 p += identifier_len;
112 if (*p == '\r')
113 p++;
114 if (*p == '\n')
115 p++;
116 }
117
118 /* cue timestamps */
119 if ((ts_start = read_ts(p)) == AV_NOPTS_VALUE)
120 break;
121 if (!(p = strstr(p, "-->")))
122 break;
123 p += 2;
124 do p++; while (*p == ' ' || *p == '\t');
125 if ((ts_end = read_ts(p)) == AV_NOPTS_VALUE)
126 break;
127
128 /* optional cue settings */
129 p += strcspn(p, "\n\t ");
130 while (*p == '\t' || *p == ' ')
131 p++;
132 settings = p;
133 settings_len = strcspn(p, "\r\n");
134 p += settings_len;
135 if (*p == '\r')
136 p++;
137 if (*p == '\n')
138 p++;
139
140 /* create packet */
141 sub = ff_subtitles_queue_insert(&webvtt->q, p, strlen(p), 0);
142 if (!sub) {
143 res = AVERROR(ENOMEM);
144 goto end;
145 }
146 sub->pos = pos;
147 sub->pts = ts_start;
148 sub->duration = ts_end - ts_start;
149
150#define SET_SIDE_DATA(name, type) do { \
151 if (name##_len) { \
152 uint8_t *buf = av_packet_new_side_data(sub, type, name##_len); \
153 if (!buf) { \
154 res = AVERROR(ENOMEM); \
155 goto end; \
156 } \
157 memcpy(buf, name, name##_len); \
158 } \
159} while (0)
160
161 SET_SIDE_DATA(identifier, AV_PKT_DATA_WEBVTT_IDENTIFIER);
162 SET_SIDE_DATA(settings, AV_PKT_DATA_WEBVTT_SETTINGS);
163 }
164
165 ff_subtitles_queue_finalize(s, &webvtt->q);
166
167end:
168 av_bprint_finalize(&cue, NULL);
169 av_bprint_finalize(&header, NULL);
170 return res;
171}
172
173static int webvtt_read_packet(AVFormatContext *s, AVPacket *pkt)
174{
175 WebVTTContext *webvtt = s->priv_data;
176 return ff_subtitles_queue_read_packet(&webvtt->q, pkt);
177}
178
179static int webvtt_read_seek(AVFormatContext *s, int stream_index,
180 int64_t min_ts, int64_t ts, int64_t max_ts, int flags)
181{
182 WebVTTContext *webvtt = s->priv_data;
183 return ff_subtitles_queue_seek(&webvtt->q, s, stream_index,
184 min_ts, ts, max_ts, flags);
185}
186
187static int webvtt_read_close(AVFormatContext *s)
188{
189 WebVTTContext *webvtt = s->priv_data;
190 ff_subtitles_queue_clean(&webvtt->q);
191 return 0;
192}
193
194#define OFFSET(x) offsetof(WebVTTContext, x)
195#define KIND_FLAGS AV_OPT_FLAG_SUBTITLE_PARAM
196
197static const AVOption options[] = {
198 { "kind", "Set kind of WebVTT track", OFFSET(kind), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, INT_MAX, KIND_FLAGS, "webvtt_kind" },
199 { "subtitles", "WebVTT subtitles kind", 0, AV_OPT_TYPE_CONST, { .i64 = 0 }, INT_MIN, INT_MAX, 0, "webvtt_kind" },
200 { "captions", "WebVTT captions kind", 0, AV_OPT_TYPE_CONST, { .i64 = AV_DISPOSITION_CAPTIONS }, INT_MIN, INT_MAX, 0, "webvtt_kind" },
201 { "descriptions", "WebVTT descriptions kind", 0, AV_OPT_TYPE_CONST, { .i64 = AV_DISPOSITION_DESCRIPTIONS }, INT_MIN, INT_MAX, 0, "webvtt_kind" },
202 { "metadata", "WebVTT metadata kind", 0, AV_OPT_TYPE_CONST, { .i64 = AV_DISPOSITION_METADATA }, INT_MIN, INT_MAX, 0, "webvtt_kind" },
203 { NULL }
204};
205
206static const AVClass webvtt_demuxer_class = {
207 .class_name = "WebVTT demuxer",
208 .item_name = av_default_item_name,
209 .option = options,
210 .version = LIBAVUTIL_VERSION_INT,
211};
212
213AVInputFormat ff_webvtt_demuxer = {
214 .name = "webvtt",
215 .long_name = NULL_IF_CONFIG_SMALL("WebVTT subtitle"),
216 .priv_data_size = sizeof(WebVTTContext),
217 .read_probe = webvtt_probe,
218 .read_header = webvtt_read_header,
219 .read_packet = webvtt_read_packet,
220 .read_seek2 = webvtt_read_seek,
221 .read_close = webvtt_read_close,
222 .extensions = "vtt",
223 .priv_class = &webvtt_demuxer_class,
224};
225
generated by cgit at 2024-05-17 04:47:45 (GMT)