1/*
2 * MP3 muxer
3 * Copyright (c) 2003 Fabrice Bellard
4 *
5 * This file is part of Libav.
6 *
7 * Libav 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 * Libav 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 Libav; if not, write to the Free Software
19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20 */
21
22#include "avformat.h"
23#include "avio_internal.h"
24#include "id3v1.h"
25#include "id3v2.h"
26#include "rawenc.h"
27#include "libavutil/avstring.h"
28#include "libavcodec/mpegaudio.h"
29#include "libavcodec/mpegaudiodata.h"
30#include "libavcodec/mpegaudiodecheader.h"
31#include "libavutil/intreadwrite.h"
32#include "libavutil/opt.h"
33#include "libavutil/dict.h"
34
35static int id3v1_set_string(AVFormatContext *s, const char *key,
36                            uint8_t *buf, int buf_size)
37{
38    AVDictionaryEntry *tag;
39    if ((tag = av_dict_get(s->metadata, key, NULL, 0)))
40        av_strlcpy(buf, tag->value, buf_size);
41    return !!tag;
42}
43
44static int id3v1_create_tag(AVFormatContext *s, uint8_t *buf)
45{
46    AVDictionaryEntry *tag;
47    int i, count = 0;
48
49    memset(buf, 0, ID3v1_TAG_SIZE); /* fail safe */
50    buf[0] = 'T';
51    buf[1] = 'A';
52    buf[2] = 'G';
53    count += id3v1_set_string(s, "TIT2",    buf +  3, 30);       //title
54    count += id3v1_set_string(s, "TPE1",    buf + 33, 30);       //author|artist
55    count += id3v1_set_string(s, "TALB",    buf + 63, 30);       //album
56    count += id3v1_set_string(s, "TDRL",    buf + 93,  4);       //date
57    count += id3v1_set_string(s, "comment", buf + 97, 30);
58    if ((tag = av_dict_get(s->metadata, "TRCK", NULL, 0))) { //track
59        buf[125] = 0;
60        buf[126] = atoi(tag->value);
61        count++;
62    }
63    buf[127] = 0xFF; /* default to unknown genre */
64    if ((tag = av_dict_get(s->metadata, "TCON", NULL, 0))) { //genre
65        for(i = 0; i <= ID3v1_GENRE_MAX; i++) {
66            if (!av_strcasecmp(tag->value, ff_id3v1_genre_str[i])) {
67                buf[127] = i;
68                count++;
69                break;
70            }
71        }
72    }
73    return count;
74}
75
76typedef struct MP3Context {
77    const AVClass *class;
78    int id3v2_version;
79    int write_id3v1;
80    int64_t nb_frames_offset;
81} MP3Context;
82
83static int mp3_write_trailer(struct AVFormatContext *s)
84{
85    uint8_t buf[ID3v1_TAG_SIZE];
86    MP3Context *mp3 = s->priv_data;
87
88    /* write the id3v1 tag */
89    if (mp3 && mp3->write_id3v1 && id3v1_create_tag(s, buf) > 0) {
90        avio_write(s->pb, buf, ID3v1_TAG_SIZE);
91    }
92
93    /* write number of frames */
94    if (mp3 && mp3->nb_frames_offset) {
95        avio_seek(s->pb, mp3->nb_frames_offset, SEEK_SET);
96        avio_wb32(s->pb, s->streams[0]->nb_frames);
97        avio_seek(s->pb, 0, SEEK_END);
98    }
99
100    avio_flush(s->pb);
101
102    return 0;
103}
104
105#if CONFIG_MP2_MUXER
106AVOutputFormat ff_mp2_muxer = {
107    .name              = "mp2",
108    .long_name         = NULL_IF_CONFIG_SMALL("MPEG audio layer 2"),
109    .mime_type         = "audio/x-mpeg",
110    .extensions        = "mp2,m2a",
111    .audio_codec       = CODEC_ID_MP2,
112    .video_codec       = CODEC_ID_NONE,
113    .write_packet      = ff_raw_write_packet,
114    .write_trailer     = mp3_write_trailer,
115};
116#endif
117
118#if CONFIG_MP3_MUXER
119
120static const AVOption options[] = {
121    { "id3v2_version", "Select ID3v2 version to write. Currently 3 and 4 are supported.",
122      offsetof(MP3Context, id3v2_version), AV_OPT_TYPE_INT, {.dbl = 4}, 3, 4, AV_OPT_FLAG_ENCODING_PARAM},
123    { "write_id3v1", "Enable ID3v1 writing. ID3v1 tags are written in UTF-8 which may not be supported by most software.",
124      offsetof(MP3Context, write_id3v1), AV_OPT_TYPE_INT, {.dbl = 0}, 0, 1, AV_OPT_FLAG_ENCODING_PARAM},
125    { NULL },
126};
127
128static const AVClass mp3_muxer_class = {
129    .class_name     = "MP3 muxer",
130    .item_name      = av_default_item_name,
131    .option         = options,
132    .version        = LIBAVUTIL_VERSION_INT,
133};
134
135/* insert a dummy frame containing number of frames */
136static void mp3_write_xing(AVFormatContext *s)
137{
138    AVCodecContext *codec = s->streams[0]->codec;
139    MP3Context       *mp3 = s->priv_data;
140    int       bitrate_idx = 1;    // 32 kbps
141    int64_t   xing_offset = (codec->channels == 2) ? 32 : 17;
142    int32_t        header;
143    MPADecodeHeader  mpah;
144    int srate_idx, i, channels;
145
146    for (i = 0; i < FF_ARRAY_ELEMS(avpriv_mpa_freq_tab); i++)
147        if (avpriv_mpa_freq_tab[i] == codec->sample_rate) {
148            srate_idx = i;
149            break;
150        }
151    if (i == FF_ARRAY_ELEMS(avpriv_mpa_freq_tab)) {
152        av_log(s, AV_LOG_ERROR, "Unsupported sample rate.\n");
153        return;
154    }
155
156    switch (codec->channels) {
157    case 1:  channels = MPA_MONO;                                          break;
158    case 2:  channels = MPA_STEREO;                                        break;
159    default: av_log(s, AV_LOG_ERROR, "Unsupported number of channels.\n"); return;
160    }
161
162    /* dummy MPEG audio header */
163    header  =  0xff                                  << 24; // sync
164    header |= (0x7 << 5 | 0x3 << 3 | 0x1 << 1 | 0x1) << 16; // sync/mpeg-1/layer 3/no crc*/
165    header |= (bitrate_idx << 4 | srate_idx << 2)    <<  8;
166    header |= channels << 6;
167    avio_wb32(s->pb, header);
168
169    avpriv_mpegaudio_decode_header(&mpah, header);
170
171    ffio_fill(s->pb, 0, xing_offset);
172    ffio_wfourcc(s->pb, "Xing");
173    avio_wb32(s->pb, 0x1);    // only number of frames
174    mp3->nb_frames_offset = avio_tell(s->pb);
175    avio_wb32(s->pb, 0);
176
177    mpah.frame_size -= 4 + xing_offset + 4 + 4 + 4;
178    ffio_fill(s->pb, 0, mpah.frame_size);
179}
180
181/**
182 * Write an ID3v2 header at beginning of stream
183 */
184
185static int mp3_write_header(struct AVFormatContext *s)
186{
187    MP3Context  *mp3 = s->priv_data;
188    int ret;
189
190    ret = ff_id3v2_write(s, mp3->id3v2_version, ID3v2_DEFAULT_MAGIC);
191    if (ret < 0)
192        return ret;
193
194    if (s->pb->seekable)
195        mp3_write_xing(s);
196
197    return 0;
198}
199
200AVOutputFormat ff_mp3_muxer = {
201    .name              = "mp3",
202    .long_name         = NULL_IF_CONFIG_SMALL("MPEG audio layer 3"),
203    .mime_type         = "audio/x-mpeg",
204    .extensions        = "mp3",
205    .priv_data_size    = sizeof(MP3Context),
206    .audio_codec       = CODEC_ID_MP3,
207    .video_codec       = CODEC_ID_NONE,
208    .write_header      = mp3_write_header,
209    .write_packet      = ff_raw_write_packet,
210    .write_trailer     = mp3_write_trailer,
211    .flags             = AVFMT_NOTIMESTAMPS,
212    .priv_class = &mp3_muxer_class,
213};
214#endif
215