From 3b99111c3d082841f0a7f5819103fb3db6ba8447 Mon Sep 17 00:00:00 2001
From: =?utf8?q?David=20=E2=80=98Bombe=E2=80=99=20Roden?=
 <bombe@pterodactylus.net>
Date: Thu, 14 Mar 2013 22:08:00 +0100
Subject: [PATCH] Add Ogg Vorbis identifier.

---
 .../sonitus/io/OggVorbisIdentifier.java            | 115 +++++++++++++++++++++
 1 file changed, 115 insertions(+)
 create mode 100644 src/main/java/net/pterodactylus/sonitus/io/OggVorbisIdentifier.java

diff --git a/src/main/java/net/pterodactylus/sonitus/io/OggVorbisIdentifier.java b/src/main/java/net/pterodactylus/sonitus/io/OggVorbisIdentifier.java
new file mode 100644
index 0000000..64ad2dd
--- /dev/null
+++ b/src/main/java/net/pterodactylus/sonitus/io/OggVorbisIdentifier.java
@@ -0,0 +1,115 @@
+/*
+ * Sonitus - OggVorbisIdentifier.java - Copyright © 2013 David Roden
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package net.pterodactylus.sonitus.io;
+
+import java.io.IOException;
+import java.io.InputStream;
+
+import net.pterodactylus.sonitus.data.Format;
+
+import com.jcraft.jogg.Packet;
+import com.jcraft.jogg.Page;
+import com.jcraft.jogg.StreamState;
+import com.jcraft.jogg.SyncState;
+import com.jcraft.jorbis.Comment;
+import com.jcraft.jorbis.Info;
+
+/**
+ * Identifies Ogg Vorbis files.
+ *
+ * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
+ */
+public class OggVorbisIdentifier {
+
+	/** The default size of the read buffer. */
+	private static final int BUFFER_SIZE = 4096;
+
+	/** Suppress default constructor. */
+	private OggVorbisIdentifier() {
+		/* nothing here. */
+	}
+
+	/**
+	 * Tries to parse the given stream as Ogg Vorbis file and returns a {@link
+	 * Format} describing the stream.
+	 *
+	 * @param inputStream
+	 * @return
+	 * @throws IOException
+	 */
+	public static Format identify(InputStream inputStream) throws IOException {
+
+		/* stuff needed to decode Ogg. */
+		Packet packet = new Packet();
+		Page page = new Page();
+		StreamState streamState = new StreamState();
+		SyncState syncState = new SyncState();
+
+		/* stuff needed to decode Vorbis. */
+		Comment comment = new Comment();
+		Info info = new Info();
+
+		/* initialize jorbis. */
+		syncState.init();
+		int bufferSize = BUFFER_SIZE;
+		int index = syncState.buffer(bufferSize);
+		byte[] buffer = syncState.data;
+
+		boolean streamStateInitialized = false;
+		int packetsRead = 0;
+
+		/* read until we have read the three packets required to decode the header. */
+		while (packetsRead < 3) {
+			int read = inputStream.read(buffer, index, bufferSize);
+			syncState.wrote(read);
+			switch (syncState.pageout(page)) {
+				case -1:
+					throw new IOException("Hole in Ogg data!");
+				case 1:
+					if (!streamStateInitialized) {
+						/* init stream state. */
+						streamState.init(page.serialno());
+						streamState.reset();
+						info.init();
+						comment.init();
+						streamStateInitialized = true;
+					}
+					if (streamState.pagein(page) == -1) {
+						throw new IOException("Error parsing Ogg data!");
+					}
+					switch (streamState.packetout(packet)) {
+						case -1:
+							throw new IOException("Error parsing Ogg data!");
+						case 1:
+							info.synthesis_headerin(comment, packet);
+							packetsRead++;
+						default:
+							/* continue. */
+					}
+
+				default:
+					/* continue. */
+			}
+			index = syncState.buffer(bufferSize);
+			buffer = syncState.data;
+		}
+
+		return new Format(info.channels, info.rate, "Vorbis");
+	}
+
+}
-- 
2.7.4