Add base class for external MP3 encoders.

diff --git a/src/main/java/net/pterodactylus/sonitus/data/filter/ExternalMp3Encoder.java b/src/main/java/net/pterodactylus/sonitus/data/filter/ExternalMp3Encoder.java
new file mode 100644 (file)
index 0000000..d26febe
--- /dev/null
+++ b/src/main/java/net/pterodactylus/sonitus/data/filter/ExternalMp3Encoder.java
@@ -0,0 +1,47 @@
+/*
+ * Sonitus - ExternalMp3Encoder.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.data.filter;
+
+import net.pterodactylus.sonitus.data.ConnectException;
+import net.pterodactylus.sonitus.data.Format;
+import net.pterodactylus.sonitus.data.Source;
+
+import com.google.common.base.Preconditions;
+
+/**
+ * Basic {@link ExternalFilter} implementation that verifies that the connected
+ * source is PCM-encoded and that returns an MP3-encoded format.
+ *
+ * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
+ */
+public abstract class ExternalMp3Encoder extends ExternalFilter {
+
+       @Override
+       public Format format() {
+               return super.format().encoding("MP3");
+       }
+
+       @Override
+       public void connect(Source source) throws ConnectException {
+               Preconditions.checkNotNull(source, "source must not be null");
+               Preconditions.checkState(source.format().encoding().equalsIgnoreCase("PCM"), "source must be PCM-encoded");
+
+               super.connect(source);
+       }
+
+}