Add LAME-based MP3 encoder.

diff --git a/src/main/java/net/pterodactylus/sonitus/data/filter/LameMp3Encoder.java b/src/main/java/net/pterodactylus/sonitus/data/filter/LameMp3Encoder.java
new file mode 100644 (file)
index 0000000..c88d939
--- /dev/null
+++ b/src/main/java/net/pterodactylus/sonitus/data/filter/LameMp3Encoder.java
@@ -0,0 +1,163 @@
+/*
+ * Sonitus - LameMp3Encoder.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 java.util.Arrays;
+
+import net.pterodactylus.sonitus.data.Format;
+
+import com.google.common.base.Optional;
+import com.google.common.collect.ImmutableList;
+
+/**
+ * {@link ExternalMp3Encoder} implementation that uses LAME to encode MP3s.
+ *
+ * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
+ */
+public class LameMp3Encoder extends ExternalMp3Encoder {
+
+       /** Preset for LAME. */
+       public enum Preset {
+
+               /** “medium” preset. */
+               MEDIUM,
+
+               /** “standard” preset. */
+               STANDARD,
+
+               /** “extreme” preset. */
+               EXTREME,
+
+               /** “insane” preset. */
+               INSANE
+
+       }
+
+       /** The location of the binary. */
+       private final String binary;
+
+       /** Whether to swap bytes in the input. */
+       private final boolean swapBytes;
+
+       /** The preset to use. */
+       private final Optional<Preset> preset;
+
+       /** The bitrate to encode to. */
+       private final Optional<Integer> bitrate;
+
+       /**
+        * Creates a new LAME MP3 encoder.
+        *
+        * @param binary
+        *              The location of the binary
+        * @param swapBytes
+        *              {@code true} to swap bytes in the input, {@code false} to use platform
+        *              endianness
+        * @param preset
+        *              The preset to use
+        */
+       public LameMp3Encoder(String binary, boolean swapBytes, Preset preset) {
+               this(binary, swapBytes, preset, -1);
+       }
+
+       /**
+        * Creates a new LAME MP3 encoder.
+        *
+        * @param binary
+        *              The location of the binary
+        * @param swapBytes
+        *              {@code true} to swap bytes in the input, {@code false} to use platform
+        *              endianness
+        * @param bitrate
+        *              The bitrate to encode to (in kbps)
+        */
+       public LameMp3Encoder(String binary, boolean swapBytes, int bitrate) {
+               this(binary, swapBytes, null, bitrate);
+       }
+
+       /**
+        * Creates a new LAME MP3 encoder.
+        *
+        * @param binary
+        *              The location of the binary
+        * @param swapBytes
+        *              {@code true} to swap bytes in the input, {@code false} to use platform
+        *              endianness
+        * @param preset
+        *              The preset to use
+        * @param bitrate
+        *              The bitrate to encode to (in kbps)
+        */
+       private LameMp3Encoder(String binary, boolean swapBytes, Preset preset, int bitrate) {
+               this.binary = binary;
+               this.swapBytes = swapBytes;
+               this.preset = Optional.fromNullable(preset);
+               this.bitrate = (bitrate < 0) ? Optional.<Integer>absent() : Optional.<Integer>of(bitrate);
+       }
+
+       //
+       // EXTERNALFILTER METHODS
+       //
+
+       @Override
+       protected String binary(Format format) {
+               return binary;
+       }
+
+       @Override
+       protected Iterable<String> parameters(Format format) {
+               ImmutableList.Builder parameters = ImmutableList.builder();
+               parameters.add("-r");
+               parameters.add("-s").add(String.valueOf(format.frequency() / 1000.0));
+               if (swapBytes) {
+                       parameters.add("-x");
+               }
+               parameters.add("--preset");
+               if (preset.isPresent()) {
+                       parameters.add(preset.get().name().toLowerCase());
+               }
+               if (bitrate.isPresent()) {
+                       if (isSignificant(bitrate.get())) {
+                               parameters.add("cbr");
+                       }
+                       parameters.add(String.valueOf(bitrate.get()));
+               }
+               parameters.add("-p");
+               parameters.add("-q").add("0");
+               parameters.add("-").add("-");
+               return parameters.build();
+       }
+
+       //
+       // STATIC METHODS
+       //
+
+       /**
+        * Returns whether the given bitrate is one of the significant bitrates of
+        * MP3.
+        *
+        * @param bitrate
+        *              The bitrate to check (in kbps)
+        * @return {@code true} if the given bitrate is one of the significant MP3
+        *         bitrates, {@code false} otherwise
+        */
+       private static boolean isSignificant(int bitrate) {
+               return Arrays.asList(80, 96, 112, 128, 160, 192, 224, 256, 320).contains(bitrate);
+       }
+
+}