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.jcraft.jogg.Packet;
  26 import com.jcraft.jogg.Page;
  27 import com.jcraft.jogg.StreamState;
  28 import com.jcraft.jogg.SyncState;
  29 import com.jcraft.jorbis.Comment;
  30 import com.jcraft.jorbis.Info;
  31
  32 /**
  33  * Identifies Ogg Vorbis files.
  34  *
  35  * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
  36  */
  37 public class OggVorbisIdentifier {
  38
  39         /** The default size of the read buffer. */
  40         private static final int BUFFER_SIZE = 4096;
  41
  42         /** Suppress default constructor. */
  43         private OggVorbisIdentifier() {
  44                 /* nothing here. */
  45         }
  46
  47         /**
  48          * Tries to parse the given stream as Ogg Vorbis file and returns a {@link
  49          * Format} describing the stream.
  50          *
  51          * @param inputStream
  52          * @return
  53          * @throws IOException
  54          */
  55         public static Format identify(InputStream inputStream) throws IOException {
  56
  57                 /* stuff needed to decode Ogg. */
  58                 Packet packet = new Packet();
  59                 Page page = new Page();
  60                 StreamState streamState = new StreamState();
  61                 SyncState syncState = new SyncState();
  62
  63                 /* stuff needed to decode Vorbis. */
  64                 Comment comment = new Comment();
  65                 Info info = new Info();
  66
  67                 /* initialize jorbis. */
  68                 syncState.init();
  69                 int bufferSize = BUFFER_SIZE;
  70                 int index = syncState.buffer(bufferSize);
  71                 byte[] buffer = syncState.data;
  72
  73                 boolean streamStateInitialized = false;
  74                 int packetsRead = 0;
  75
  76                 /* read until we have read the three packets required to decode the header. */
  77                 while (packetsRead < 3) {
  78                         int read = inputStream.read(buffer, index, bufferSize);
  79                         syncState.wrote(read);
  80                         switch (syncState.pageout(page)) {
  81                                 case -1:
  82                                         throw new IOException("Hole in Ogg data!");
  83                                 case 1:
  84                                         if (!streamStateInitialized) {
  85                                                 /* init stream state. */
  86                                                 streamState.init(page.serialno());
  87                                                 streamState.reset();
  88                                                 info.init();
  89                                                 comment.init();
  90                                                 streamStateInitialized = true;
  91                                         }
  92                                         if (streamState.pagein(page) == -1) {
  93                                                 throw new IOException("Error parsing Ogg data!");
  94                                         }
  95                                         switch (streamState.packetout(packet)) {
  96                                                 case -1:
  97                                                         throw new IOException("Error parsing Ogg data!");
  98                                                 case 1:
  99                                                         info.synthesis_headerin(comment, packet);
 100                                                         packetsRead++;
 101                                                 default:
 102                                                         /* continue. */
 103                                         }
 104
 105                                 default:
 106                                         /* continue. */
 107                         }
 108                         index = syncState.buffer(bufferSize);
 109                         buffer = syncState.data;
 110                 }
 111
 112                 return new Format(info.channels, info.rate, "Vorbis");
 113         }
 114
 115 }