1 /*
2 * LRC lyrics file format decoder
3 * Copyright (c) 2014 StarBrilliant <m13253@hotmail.com>
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 <inttypes.h>
23 #include <stdint.h>
24 #include <string.h>
25
26 #include "avformat.h"
27 #include "internal.h"
28 #include "lrc.h"
29 #include "metadata.h"
30 #include "subtitles.h"
31 #include "libavutil/bprint.h"
32 #include "libavutil/dict.h"
33
34 typedef struct LRCContext {
35 FFDemuxSubtitlesQueue q;
36 int64_t ts_offset; // offset metadata item
37 } LRCContext;
38
find_header(const char * p)39 static int64_t find_header(const char *p)
40 {
41 int64_t offset = 0;
42 while(p[offset] == ' ' || p[offset] == '\t') {
43 offset++;
44 }
45 if(p[offset] == '[' && p[offset + 1] >= 'a' && p[offset + 1] <= 'z') {
46 return offset;
47 } else {
48 return -1;
49 }
50 }
51
count_ts(const char * p)52 static int64_t count_ts(const char *p)
53 {
54 int64_t offset = 0;
55 int in_brackets = 0;
56
57 for(;;) {
58 if(p[offset] == ' ' || p[offset] == '\t') {
59 offset++;
60 } else if(p[offset] == '[') {
61 offset++;
62 in_brackets++;
63 } else if (p[offset] == ']' && in_brackets) {
64 offset++;
65 in_brackets--;
66 } else if(in_brackets &&
67 (p[offset] == ':' || p[offset] == '.' || p[offset] == '-' ||
68 (p[offset] >= '0' && p[offset] <= '9'))) {
69 offset++;
70 } else {
71 break;
72 }
73 }
74 return offset;
75 }
76
read_ts(const char * p,int64_t * start)77 static int64_t read_ts(const char *p, int64_t *start)
78 {
79 int64_t offset = 0;
80 uint64_t mm, ss, cs;
81
82 while(p[offset] == ' ' || p[offset] == '\t') {
83 offset++;
84 }
85 if(p[offset] != '[') {
86 return 0;
87 }
88 if(sscanf(p, "[-%"SCNu64":%"SCNu64".%"SCNu64"]", &mm, &ss, &cs) == 3) {
89 /* Just in case negative pts, players may drop it but we won't. */
90 *start = -(int64_t) (mm*60000 + ss*1000 + cs*10);
91 } else if(sscanf(p, "[%"SCNu64":%"SCNu64".%"SCNu64"]", &mm, &ss, &cs) == 3) {
92 *start = mm*60000 + ss*1000 + cs*10;
93 } else {
94 return 0;
95 }
96 do {
97 offset++;
98 } while(p[offset] && p[offset-1] != ']');
99 return offset;
100 }
101
read_line(AVBPrint * buf,AVIOContext * pb)102 static int64_t read_line(AVBPrint *buf, AVIOContext *pb)
103 {
104 int64_t pos = avio_tell(pb);
105
106 av_bprint_clear(buf);
107 while(!avio_feof(pb)) {
108 int c = avio_r8(pb);
109 if(c != '\r') {
110 av_bprint_chars(buf, c, 1);
111 }
112 if(c == '\n') {
113 break;
114 }
115 }
116 return pos;
117 }
118
lrc_probe(const AVProbeData * p)119 static int lrc_probe(const AVProbeData *p)
120 {
121 int64_t offset = 0;
122 int64_t mm;
123 uint64_t ss, cs;
124 const AVMetadataConv *metadata_item;
125
126 if(!memcmp(p->buf, "\xef\xbb\xbf", 3)) { // Skip UTF-8 BOM header
127 offset += 3;
128 }
129 while(p->buf[offset] == '\n' || p->buf[offset] == '\r') {
130 offset++;
131 }
132 if(p->buf[offset] != '[') {
133 return 0;
134 }
135 offset++;
136 // Common metadata item but not exist in ff_lrc_metadata_conv
137 if(!memcmp(p->buf + offset, "offset:", 7)) {
138 return 40;
139 }
140 if(sscanf(p->buf + offset, "%"SCNd64":%"SCNu64".%"SCNu64"]",
141 &mm, &ss, &cs) == 3) {
142 return 50;
143 }
144 // Metadata items exist in ff_lrc_metadata_conv
145 for(metadata_item = ff_lrc_metadata_conv;
146 metadata_item->native; metadata_item++) {
147 size_t metadata_item_len = strlen(metadata_item->native);
148 if(p->buf[offset + metadata_item_len] == ':' &&
149 !memcmp(p->buf + offset, metadata_item->native, metadata_item_len)) {
150 return 40;
151 }
152 }
153 return 5; // Give it 5 scores since it starts with a bracket
154 }
155
lrc_read_header(AVFormatContext * s)156 static int lrc_read_header(AVFormatContext *s)
157 {
158 LRCContext *lrc = s->priv_data;
159 AVBPrint line;
160 AVStream *st;
161
162 st = avformat_new_stream(s, NULL);
163 if(!st) {
164 return AVERROR(ENOMEM);
165 }
166 avpriv_set_pts_info(st, 64, 1, 1000);
167 lrc->ts_offset = 0;
168 st->codecpar->codec_type = AVMEDIA_TYPE_SUBTITLE;
169 st->codecpar->codec_id = AV_CODEC_ID_TEXT;
170 av_bprint_init(&line, 0, AV_BPRINT_SIZE_UNLIMITED);
171
172 while(!avio_feof(s->pb)) {
173 int64_t pos = read_line(&line, s->pb);
174 int64_t header_offset = find_header(line.str);
175 if(header_offset >= 0) {
176 char *comma_offset = strchr(line.str, ':');
177 if(comma_offset) {
178 char *right_bracket_offset = strchr(line.str, ']');
179 if(!right_bracket_offset) {
180 continue;
181 }
182
183 *right_bracket_offset = *comma_offset = '\0';
184 if(strcmp(line.str + 1, "offset") ||
185 sscanf(comma_offset + 1, "%"SCNd64, &lrc->ts_offset) != 1) {
186 av_dict_set(&s->metadata, line.str + 1, comma_offset + 1, 0);
187 }
188 lrc->ts_offset = av_clip64(lrc->ts_offset, INT64_MIN/4, INT64_MAX/4);
189
190 *comma_offset = ':';
191 *right_bracket_offset = ']';
192 }
193
194 } else {
195 AVPacket *sub;
196 int64_t ts_start = AV_NOPTS_VALUE;
197 int64_t ts_stroffset = 0;
198 int64_t ts_stroffset_incr = 0;
199 int64_t ts_strlength = count_ts(line.str);
200
201 while((ts_stroffset_incr = read_ts(line.str + ts_stroffset,
202 &ts_start)) != 0) {
203 ts_start = av_clip64(ts_start, INT64_MIN/4, INT64_MAX/4);
204 ts_stroffset += ts_stroffset_incr;
205 sub = ff_subtitles_queue_insert(&lrc->q, line.str + ts_strlength,
206 line.len - ts_strlength, 0);
207 if(!sub) {
208 ff_subtitles_queue_clean(&lrc->q);
209 return AVERROR(ENOMEM);
210 }
211 sub->pos = pos;
212 sub->pts = ts_start - lrc->ts_offset;
213 sub->duration = -1;
214 }
215 }
216 }
217 ff_subtitles_queue_finalize(s, &lrc->q);
218 ff_metadata_conv_ctx(s, NULL, ff_lrc_metadata_conv);
219 av_bprint_finalize(&line, NULL);
220 return 0;
221 }
222
lrc_read_packet(AVFormatContext * s,AVPacket * pkt)223 static int lrc_read_packet(AVFormatContext *s, AVPacket *pkt)
224 {
225 LRCContext *lrc = s->priv_data;
226 return ff_subtitles_queue_read_packet(&lrc->q, pkt);
227 }
228
lrc_read_seek(AVFormatContext * s,int stream_index,int64_t min_ts,int64_t ts,int64_t max_ts,int flags)229 static int lrc_read_seek(AVFormatContext *s, int stream_index,
230 int64_t min_ts, int64_t ts, int64_t max_ts, int flags)
231 {
232 LRCContext *lrc = s->priv_data;
233 return ff_subtitles_queue_seek(&lrc->q, s, stream_index,
234 min_ts, ts, max_ts, flags);
235 }
236
lrc_read_close(AVFormatContext * s)237 static int lrc_read_close(AVFormatContext *s)
238 {
239 LRCContext *lrc = s->priv_data;
240 ff_subtitles_queue_clean(&lrc->q);
241 return 0;
242 }
243
244 AVInputFormat ff_lrc_demuxer = {
245 .name = "lrc",
246 .long_name = NULL_IF_CONFIG_SMALL("LRC lyrics"),
247 .priv_data_size = sizeof (LRCContext),
248 .read_probe = lrc_probe,
249 .read_header = lrc_read_header,
250 .read_packet = lrc_read_packet,
251 .read_close = lrc_read_close,
252 .read_seek2 = lrc_read_seek
253 };
254