2 * Sonitus - OggVorbisIdentifier.java - Copyright © 2013 David Roden
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.
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.
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/>.
18 package net.pterodactylus.sonitus.io;
20 import java.io.IOException;
21 import java.io.InputStream;
23 import net.pterodactylus.sonitus.data.Format;
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;
34 * Identifies Ogg Vorbis files.
36 * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
38 public class OggVorbisIdentifier {
40 /** The default size of the read buffer. */
41 private static final int BUFFER_SIZE = 4096;
43 /** Suppress default constructor. */
44 private OggVorbisIdentifier() {
49 * Tries to parse the given stream as Ogg Vorbis file and returns a {@link
50 * Format} describing the stream.
53 * The input stream to identify as Ogg Vorbis
54 * @return The identified format, or {@link com.google.common.base.Optional#absent()}
55 * if the stream could not be identified
57 * if an I/O error occurs
59 public static Optional<Format> identify(InputStream inputStream) throws IOException {
61 /* stuff needed to decode Ogg. */
62 Packet packet = new Packet();
63 Page page = new Page();
64 StreamState streamState = new StreamState();
65 SyncState syncState = new SyncState();
67 /* stuff needed to decode Vorbis. */
68 Comment comment = new Comment();
69 Info info = new Info();
71 /* initialize jorbis. */
73 int bufferSize = BUFFER_SIZE;
74 int index = syncState.buffer(bufferSize);
75 byte[] buffer = syncState.data;
77 boolean streamStateInitialized = false;
80 /* read until we have read the three packets required to decode the header. */
81 while (packetsRead < 3) {
82 int read = inputStream.read(buffer, index, bufferSize);
83 syncState.wrote(read);
84 switch (syncState.pageout(page)) {
86 return Optional.absent();
88 if (!streamStateInitialized) {
89 /* init stream state. */
90 streamState.init(page.serialno());
94 streamStateInitialized = true;
96 if (streamState.pagein(page) == -1) {
97 return Optional.absent();
99 switch (streamState.packetout(packet)) {
101 return Optional.absent();
103 info.synthesis_headerin(comment, packet);
112 index = syncState.buffer(bufferSize);
113 buffer = syncState.data;
116 return Optional.of(new Format(info.channels, info.rate, "Vorbis"));