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libavformat/mp3enc.c

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00001 /*
00002  * MP3 muxer
00003  * Copyright (c) 2003 Fabrice Bellard
00004  *
00005  * This file is part of Libav.
00006  *
00007  * Libav is free software; you can redistribute it and/or
00008  * modify it under the terms of the GNU Lesser General Public
00009  * License as published by the Free Software Foundation; either
00010  * version 2.1 of the License, or (at your option) any later version.
00011  *
00012  * Libav is distributed in the hope that it will be useful,
00013  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00014  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00015  * Lesser General Public License for more details.
00016  *
00017  * You should have received a copy of the GNU Lesser General Public
00018  * License along with Libav; if not, write to the Free Software
00019  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
00020  */
00021 
00022 #include "avformat.h"
00023 #include "avio_internal.h"
00024 #include "id3v1.h"
00025 #include "id3v2.h"
00026 #include "rawenc.h"
00027 #include "libavutil/avstring.h"
00028 #include "libavcodec/mpegaudio.h"
00029 #include "libavcodec/mpegaudiodata.h"
00030 #include "libavcodec/mpegaudiodecheader.h"
00031 #include "libavutil/intreadwrite.h"
00032 #include "libavutil/opt.h"
00033 #include "libavutil/dict.h"
00034 
00035 static int id3v1_set_string(AVFormatContext *s, const char *key,
00036                             uint8_t *buf, int buf_size)
00037 {
00038     AVDictionaryEntry *tag;
00039     if ((tag = av_dict_get(s->metadata, key, NULL, 0)))
00040         av_strlcpy(buf, tag->value, buf_size);
00041     return !!tag;
00042 }
00043 
00044 static int id3v1_create_tag(AVFormatContext *s, uint8_t *buf)
00045 {
00046     AVDictionaryEntry *tag;
00047     int i, count = 0;
00048 
00049     memset(buf, 0, ID3v1_TAG_SIZE); /* fail safe */
00050     buf[0] = 'T';
00051     buf[1] = 'A';
00052     buf[2] = 'G';
00053     count += id3v1_set_string(s, "TIT2",    buf +  3, 30);       //title
00054     count += id3v1_set_string(s, "TPE1",    buf + 33, 30);       //author|artist
00055     count += id3v1_set_string(s, "TALB",    buf + 63, 30);       //album
00056     count += id3v1_set_string(s, "TDRL",    buf + 93,  4);       //date
00057     count += id3v1_set_string(s, "comment", buf + 97, 30);
00058     if ((tag = av_dict_get(s->metadata, "TRCK", NULL, 0))) { //track
00059         buf[125] = 0;
00060         buf[126] = atoi(tag->value);
00061         count++;
00062     }
00063     buf[127] = 0xFF; /* default to unknown genre */
00064     if ((tag = av_dict_get(s->metadata, "TCON", NULL, 0))) { //genre
00065         for(i = 0; i <= ID3v1_GENRE_MAX; i++) {
00066             if (!av_strcasecmp(tag->value, ff_id3v1_genre_str[i])) {
00067                 buf[127] = i;
00068                 count++;
00069                 break;
00070             }
00071         }
00072     }
00073     return count;
00074 }
00075 
00076 typedef struct MP3Context {
00077     const AVClass *class;
00078     int id3v2_version;
00079     int write_id3v1;
00080     int64_t nb_frames_offset;
00081 } MP3Context;
00082 
00083 static int mp3_write_trailer(struct AVFormatContext *s)
00084 {
00085     uint8_t buf[ID3v1_TAG_SIZE];
00086     MP3Context *mp3 = s->priv_data;
00087 
00088     /* write the id3v1 tag */
00089     if (mp3 && mp3->write_id3v1 && id3v1_create_tag(s, buf) > 0) {
00090         avio_write(s->pb, buf, ID3v1_TAG_SIZE);
00091     }
00092 
00093     /* write number of frames */
00094     if (mp3 && mp3->nb_frames_offset) {
00095         avio_seek(s->pb, mp3->nb_frames_offset, SEEK_SET);
00096         avio_wb32(s->pb, s->streams[0]->nb_frames);
00097         avio_seek(s->pb, 0, SEEK_END);
00098     }
00099 
00100     avio_flush(s->pb);
00101 
00102     return 0;
00103 }
00104 
00105 #if CONFIG_MP2_MUXER
00106 AVOutputFormat ff_mp2_muxer = {
00107     .name              = "mp2",
00108     .long_name         = NULL_IF_CONFIG_SMALL("MPEG audio layer 2"),
00109     .mime_type         = "audio/x-mpeg",
00110     .extensions        = "mp2,m2a",
00111     .audio_codec       = CODEC_ID_MP2,
00112     .video_codec       = CODEC_ID_NONE,
00113     .write_packet      = ff_raw_write_packet,
00114     .write_trailer     = mp3_write_trailer,
00115 };
00116 #endif
00117 
00118 #if CONFIG_MP3_MUXER
00119 
00120 static const AVOption options[] = {
00121     { "id3v2_version", "Select ID3v2 version to write. Currently 3 and 4 are supported.",
00122       offsetof(MP3Context, id3v2_version), AV_OPT_TYPE_INT, {.dbl = 4}, 3, 4, AV_OPT_FLAG_ENCODING_PARAM},
00123     { "write_id3v1", "Enable ID3v1 writing. ID3v1 tags are written in UTF-8 which may not be supported by most software.",
00124       offsetof(MP3Context, write_id3v1), AV_OPT_TYPE_INT, {.dbl = 0}, 0, 1, AV_OPT_FLAG_ENCODING_PARAM},
00125     { NULL },
00126 };
00127 
00128 static const AVClass mp3_muxer_class = {
00129     .class_name     = "MP3 muxer",
00130     .item_name      = av_default_item_name,
00131     .option         = options,
00132     .version        = LIBAVUTIL_VERSION_INT,
00133 };
00134 
00135 /* insert a dummy frame containing number of frames */
00136 static void mp3_write_xing(AVFormatContext *s)
00137 {
00138     AVCodecContext *codec = s->streams[0]->codec;
00139     MP3Context       *mp3 = s->priv_data;
00140     int       bitrate_idx = 1;    // 32 kbps
00141     int64_t   xing_offset = (codec->channels == 2) ? 32 : 17;
00142     int32_t        header;
00143     MPADecodeHeader  mpah;
00144     int srate_idx, i, channels;
00145 
00146     for (i = 0; i < FF_ARRAY_ELEMS(avpriv_mpa_freq_tab); i++)
00147         if (avpriv_mpa_freq_tab[i] == codec->sample_rate) {
00148             srate_idx = i;
00149             break;
00150         }
00151     if (i == FF_ARRAY_ELEMS(avpriv_mpa_freq_tab)) {
00152         av_log(s, AV_LOG_ERROR, "Unsupported sample rate.\n");
00153         return;
00154     }
00155 
00156     switch (codec->channels) {
00157     case 1:  channels = MPA_MONO;                                          break;
00158     case 2:  channels = MPA_STEREO;                                        break;
00159     default: av_log(s, AV_LOG_ERROR, "Unsupported number of channels.\n"); return;
00160     }
00161 
00162     /* dummy MPEG audio header */
00163     header  =  0xff                                  << 24; // sync
00164     header |= (0x7 << 5 | 0x3 << 3 | 0x1 << 1 | 0x1) << 16; // sync/mpeg-1/layer 3/no crc*/
00165     header |= (bitrate_idx << 4 | srate_idx << 2)    <<  8;
00166     header |= channels << 6;
00167     avio_wb32(s->pb, header);
00168 
00169     avpriv_mpegaudio_decode_header(&mpah, header);
00170 
00171     ffio_fill(s->pb, 0, xing_offset);
00172     ffio_wfourcc(s->pb, "Xing");
00173     avio_wb32(s->pb, 0x1);    // only number of frames
00174     mp3->nb_frames_offset = avio_tell(s->pb);
00175     avio_wb32(s->pb, 0);
00176 
00177     mpah.frame_size -= 4 + xing_offset + 4 + 4 + 4;
00178     ffio_fill(s->pb, 0, mpah.frame_size);
00179 }
00180 
00185 static int mp3_write_header(struct AVFormatContext *s)
00186 {
00187     MP3Context  *mp3 = s->priv_data;
00188     int ret;
00189 
00190     ret = ff_id3v2_write(s, mp3->id3v2_version, ID3v2_DEFAULT_MAGIC);
00191     if (ret < 0)
00192         return ret;
00193 
00194     if (s->pb->seekable)
00195         mp3_write_xing(s);
00196 
00197     return 0;
00198 }
00199 
00200 AVOutputFormat ff_mp3_muxer = {
00201     .name              = "mp3",
00202     .long_name         = NULL_IF_CONFIG_SMALL("MPEG audio layer 3"),
00203     .mime_type         = "audio/x-mpeg",
00204     .extensions        = "mp3",
00205     .priv_data_size    = sizeof(MP3Context),
00206     .audio_codec       = CODEC_ID_MP3,
00207     .video_codec       = CODEC_ID_NONE,
00208     .write_header      = mp3_write_header,
00209     .write_packet      = ff_raw_write_packet,
00210     .write_trailer     = mp3_write_trailer,
00211     .flags             = AVFMT_NOTIMESTAMPS,
00212     .priv_class = &mp3_muxer_class,
00213 };
00214 #endif
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