src/main/java/net/pterodactylus/sonitus/io/OggVorbisIdentifier.java

   1 /*
   2  * Sonitus - OggVorbisIdentifier.java - Copyright © 2013 David Roden
   3  *
   4  * This program is free software: you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation, either version 3 of the License, or
   7  * (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  16  */
  17
  18 package net.pterodactylus.sonitus.io;
  19
  20 import java.io.IOException;
  21 import java.io.InputStream;
  22
  23 import net.pterodactylus.sonitus.data.Metadata;
  24
  25 import com.google.common.base.Optional;
  26 import com.jcraft.jogg.Packet;
  27 import com.jcraft.jogg.Page;
  28 import com.jcraft.jogg.StreamState;
  29 import com.jcraft.jogg.SyncState;
  30 import com.jcraft.jorbis.Comment;
  31 import com.jcraft.jorbis.Info;
  32
  33 /**
  34  * Identifies Ogg Vorbis files. <p> All knowledge used in this class has been
  35  * taken from <a href="http://www.jcraft.com/jorbis/tutorial/Tutorial.html">jcraft.com/jorbis/tutorial/Tutorial.html</a>.
  36  * </p>
  37  *
  38  * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
  39  */
  40 public class OggVorbisIdentifier {
  41
  42         /** The default size of the read buffer. */
  43         private static final int BUFFER_SIZE = 4096;
  44
  45         /** Suppress default constructor. */
  46         private OggVorbisIdentifier() {
  47                 /* nothing here. */
  48         }
  49
  50         /**
  51          * Tries to parse the given stream as Ogg Vorbis file and returns a {@link
  52          * Metadata} describing the stream.
  53          *
  54          * @param inputStream
  55          *              The input stream to identify as Ogg Vorbis
  56          * @return The identified metadata, or {@link Optional#absent()} if the stream
  57          *         could not be identified
  58          * @throws IOException
  59          *              if an I/O error occurs
  60          */
  61         public static Optional<Metadata> identify(InputStream inputStream) throws IOException {
  62
  63                 /* stuff needed to decode Ogg. */
  64                 Packet packet = new Packet();
  65                 Page page = new Page();
  66                 StreamState streamState = new StreamState();
  67                 SyncState syncState = new SyncState();
  68
  69                 /* stuff needed to decode Vorbis. */
  70                 Comment comment = new Comment();
  71                 Info info = new Info();
  72
  73                 /* initialize jorbis. */
  74                 syncState.init();
  75                 int bufferSize = BUFFER_SIZE;
  76                 int index = syncState.buffer(bufferSize);
  77                 byte[] buffer = syncState.data;
  78
  79                 boolean streamStateInitialized = false;
  80                 int packetsRead = 0;
  81
  82                 /* read until we have read the three packets required to decode the header. */
  83                 while (packetsRead < 3) {
  84                         int read = inputStream.read(buffer, index, bufferSize);
  85                         syncState.wrote(read);
  86                         switch (syncState.pageout(page)) {
  87                                 case -1:
  88                                         return Optional.absent();
  89                                 case 1:
  90                                         if (!streamStateInitialized) {
  91                                                 /* init stream state. */
  92                                                 streamState.init(page.serialno());
  93                                                 streamState.reset();
  94                                                 info.init();
  95                                                 comment.init();
  96                                                 streamStateInitialized = true;
  97                                         }
  98                                         if (streamState.pagein(page) == -1) {
  99                                                 return Optional.absent();
 100                                         }
 101                                         switch (streamState.packetout(packet)) {
 102                                                 case -1:
 103                                                         return Optional.absent();
 104                                                 case 1:
 105                                                         info.synthesis_headerin(comment, packet);
 106                                                         packetsRead++;
 107                                                 default:
 108                                                         /* continue. */
 109                                         }
 110
 111                                 default:
 112                                         /* continue. */
 113                         }
 114                         index = syncState.buffer(bufferSize);
 115                         buffer = syncState.data;
 116                 }
 117
 118                 Metadata metadata = new Metadata(info.channels, info.rate, "Vorbis");
 119                 for (int c = 0; c < comment.comments; ++c) {
 120                         String field = comment.getComment(c);
 121                         Optional<String> extractedField = extractField(field, "ARTIST");
 122                         if (extractedField.isPresent()) {
 123                                 metadata = metadata.artist(extractedField.get());
 124                                 continue;
 125                         }
 126                         extractedField = extractField(field, "TITLE");
 127                         if (extractedField.isPresent()) {
 128                                 metadata = metadata.name(extractedField.get());
 129                                 continue;
 130                         }
 131                 }
 132                 return Optional.of(metadata);
 133         }
 134
 135         /**
 136          * Extracts the content of the field from the comment if the comment contains
 137          * the given field.
 138          *
 139          * @param comment
 140          *              The comment to extract the value from
 141          * @param fieldName
 142          *              The name of the field to extract
 143          * @return The extracted field, or {@link Optional#absent()} if the comment
 144          *         does not contain the given field
 145          */
 146         private static Optional<String> extractField(String comment, String fieldName) {
 147                 if (comment.startsWith(fieldName + "=")) {
 148                         return Optional.of(comment.substring(fieldName.length() + 1));
 149                 }
 150                 return Optional.absent();
 151         }
 152
 153 }