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.Format;
  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.
  35  * <p>
  36  * All knowledge used in this class has been taken from <a
  37  * href="http://www.jcraft.com/jorbis/tutorial/Tutorial.html">jcraft.com/jorbis/tutorial/Tutorial.html</a>.
  38  * </p>
  39  *
  40  * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
  41  */
  42 public class OggVorbisIdentifier {
  43
  44         /** The default size of the read buffer. */
  45         private static final int BUFFER_SIZE = 4096;
  46
  47         /** Suppress default constructor. */
  48         private OggVorbisIdentifier() {
  49                 /* nothing here. */
  50         }
  51
  52         /**
  53          * Tries to parse the given stream as Ogg Vorbis file and returns a {@link
  54          * Format} describing the stream.
  55          *
  56          * @param inputStream
  57          *              The input stream to identify as Ogg Vorbis
  58          * @return The identified format, or {@link com.google.common.base.Optional#absent()}
  59          *         if the stream could not be identified
  60          * @throws IOException
  61          *              if an I/O error occurs
  62          */
  63         public static Optional<Format> identify(InputStream inputStream) throws IOException {
  64
  65                 /* stuff needed to decode Ogg. */
  66                 Packet packet = new Packet();
  67                 Page page = new Page();
  68                 StreamState streamState = new StreamState();
  69                 SyncState syncState = new SyncState();
  70
  71                 /* stuff needed to decode Vorbis. */
  72                 Comment comment = new Comment();
  73                 Info info = new Info();
  74
  75                 /* initialize jorbis. */
  76                 syncState.init();
  77                 int bufferSize = BUFFER_SIZE;
  78                 int index = syncState.buffer(bufferSize);
  79                 byte[] buffer = syncState.data;
  80
  81                 boolean streamStateInitialized = false;
  82                 int packetsRead = 0;
  83
  84                 /* read until we have read the three packets required to decode the header. */
  85                 while (packetsRead < 3) {
  86                         int read = inputStream.read(buffer, index, bufferSize);
  87                         syncState.wrote(read);
  88                         switch (syncState.pageout(page)) {
  89                                 case -1:
  90                                         return Optional.absent();
  91                                 case 1:
  92                                         if (!streamStateInitialized) {
  93                                                 /* init stream state. */
  94                                                 streamState.init(page.serialno());
  95                                                 streamState.reset();
  96                                                 info.init();
  97                                                 comment.init();
  98                                                 streamStateInitialized = true;
  99                                         }
 100                                         if (streamState.pagein(page) == -1) {
 101                                                 return Optional.absent();
 102                                         }
 103                                         switch (streamState.packetout(packet)) {
 104                                                 case -1:
 105                                                         return Optional.absent();
 106                                                 case 1:
 107                                                         info.synthesis_headerin(comment, packet);
 108                                                         packetsRead++;
 109                                                 default:
 110                                                         /* continue. */
 111                                         }
 112
 113                                 default:
 114                                         /* continue. */
 115                         }
 116                         index = syncState.buffer(bufferSize);
 117                         buffer = syncState.data;
 118                 }
 119
 120                 return Optional.of(new Format(info.channels, info.rate, "Vorbis"));
 121         }
 122
 123 }