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 "version.h"
32 #include "libavutil/bprint.h"
33 #include "libavutil/dict.h"
34 #include "libavutil/log.h"
35 #include "libavutil/macros.h"
36 
lrc_write_header(AVFormatContext * s)37 static int lrc_write_header(AVFormatContext *s)
38 {
39     const AVDictionaryEntry *metadata_item;
40 
41     if(s->nb_streams != 1 ||
42        s->streams[0]->codec->codec_type != AVMEDIA_TYPE_SUBTITLE) {
43         av_log(s, AV_LOG_ERROR,
44                "LRC supports only a single subtitle stream.\n");
45         return AVERROR(EINVAL);
46     }
47     if(s->streams[0]->codec->codec_id != AV_CODEC_ID_SUBRIP &&
48        s->streams[0]->codec->codec_id != AV_CODEC_ID_TEXT) {
49         av_log(s, AV_LOG_ERROR, "Unsupported subtitle codec: %s\n",
50                avcodec_get_name(s->streams[0]->codec->codec_id));
51         return AVERROR(EINVAL);
52     }
53     avpriv_set_pts_info(s->streams[0], 64, 1, 100);
54 
55     ff_metadata_conv_ctx(s, ff_lrc_metadata_conv, NULL);
56     if(!(s->flags & AVFMT_FLAG_BITEXACT)) { // avoid breaking regression tests
57         /* LRC provides a metadata slot for specifying encoder version
58          * in addition to encoder name. We will store LIBAVFORMAT_VERSION
59          * to it.
60          */
61         av_dict_set(&s->metadata, "ve", AV_STRINGIFY(LIBAVFORMAT_VERSION), 0);
62     } else {
63         av_dict_set(&s->metadata, "ve", NULL, 0);
64     }
65     for(metadata_item = NULL;
66        (metadata_item = av_dict_get(s->metadata, "", metadata_item,
67                                     AV_DICT_IGNORE_SUFFIX));) {
68         char *delim;
69         if(!metadata_item->value[0]) {
70             continue;
71         }
72         while((delim = strchr(metadata_item->value, '\n'))) {
73             *delim = ' ';
74         }
75         while((delim = strchr(metadata_item->value, '\r'))) {
76             *delim = ' ';
77         }
78         avio_printf(s->pb, "[%s:%s]\n",
79                     metadata_item->key, metadata_item->value);
80     }
81     avio_printf(s->pb, "\n");
82     return 0;
83 }
84 
lrc_write_packet(AVFormatContext * s,AVPacket * pkt)85 static int lrc_write_packet(AVFormatContext *s, AVPacket *pkt)
86 {
87     if(pkt->pts != AV_NOPTS_VALUE) {
88         char *data = av_malloc(pkt->size + 1);
89         char *line;
90         char *delim;
91 
92         if(!data) {
93             return AVERROR(ENOMEM);
94         }
95         memcpy(data, pkt->data, pkt->size);
96         data[pkt->size] = '\0';
97 
98         for(delim = data + pkt->size - 1;
99             delim >= data && (delim[0] == '\n' || delim[0] == '\r'); delim--) {
100             delim[0] = '\0'; // Strip last empty lines
101         }
102         line = data;
103         while(line[0] == '\n' || line[0] == '\r') {
104             line++; // Skip first empty lines
105         }
106 
107         while(line) {
108             delim = strchr(line, '\n');
109             if(delim) {
110                 if(delim > line && delim[-1] == '\r') {
111                     delim[-1] = '\0';
112                 }
113                 delim[0] = '\0';
114                 delim++;
115             }
116             if(line[0] == '[') {
117                 av_log(s, AV_LOG_WARNING,
118                        "Subtitle starts with '[', may cause problems with LRC format.\n");
119             }
120 
121             if(pkt->pts >= 0) {
122                 avio_printf(s->pb, "[%02"PRId64":%02"PRId64".%02"PRId64"]",
123                             (pkt->pts / 6000),
124                             ((pkt->pts / 100) % 60),
125                             (pkt->pts % 100));
126             } else {
127                 /* Offset feature of LRC can easily make pts negative,
128                  * we just output it directly and let the player drop it. */
129                 avio_printf(s->pb, "[-%02"PRId64":%02"PRId64".%02"PRId64"]",
130                             (-pkt->pts) / 6000,
131                             ((-pkt->pts) / 100) % 60,
132                             (-pkt->pts) % 100);
133             }
134             avio_printf(s->pb, "%s\n", line);
135             line = delim;
136         }
137         av_free(data);
138     }
139     return 0;
140 }
141 
142 AVOutputFormat ff_lrc_muxer = {
143 	.name           = "lrc",
144     .long_name      = NULL_IF_CONFIG_SMALL("LRC lyrics"),
145     .extensions     = "lrc",
146     .priv_data_size = 0,
147     .write_header   = lrc_write_header,
148     .write_packet   = lrc_write_packet,
149     .flags          = AVFMT_VARIABLE_FPS | AVFMT_GLOBALHEADER |
150                       AVFMT_TS_NEGATIVE | AVFMT_TS_NONSTRICT,
151     .subtitle_codec = AV_CODEC_ID_SUBRIP
152 };
153