Add resampling filter that uses sox for the heavy lifting.

diff --git a/src/main/java/net/pterodactylus/sonitus/data/filter/SoxResampleFilter.java b/src/main/java/net/pterodactylus/sonitus/data/filter/SoxResampleFilter.java
new file mode 100644 (file)
index 0000000..69daa99
--- /dev/null
+++ b/src/main/java/net/pterodactylus/sonitus/data/filter/SoxResampleFilter.java
@@ -0,0 +1,104 @@
+/*
+ * Sonitus - ResampleFilter.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 static com.google.common.base.Preconditions.*;
+
+import net.pterodactylus.sonitus.data.ConnectException;
+import net.pterodactylus.sonitus.data.Metadata;
+import net.pterodactylus.sonitus.data.Source;
+
+import com.google.common.collect.ImmutableList;
+
+/**
+ * {@link net.pterodactylus.sonitus.data.Filter} implementation that uses {@code
+ * sox} to resample a PCM-encoded source.
+ *
+ * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
+ */
+public class SoxResampleFilter extends ExternalFilter {
+
+       /** The location of the binary. */
+       private final String binary;
+
+       /** The final sampling rate. */
+       private final int rate;
+
+       /**
+        * Creates a new resample filter.
+        *
+        * @param binary
+        *              The location of the binary
+        * @param rate
+        *              The new sampling rate
+        */
+       public SoxResampleFilter(String binary, int rate) {
+               this.binary = binary;
+               this.rate = rate;
+       }
+
+       //
+       // FILTER METHODS
+       //
+
+       @Override
+       public Metadata metadata() {
+               return super.metadata().frequency(rate);
+       }
+
+       @Override
+       public void connect(Source source) throws ConnectException {
+               checkNotNull(source, "source must not be null");
+               checkArgument(source.metadata().encoding().equalsIgnoreCase("PCM"), "source must be PCM-encoded");
+
+               super.connect(source);
+       }
+
+       //
+       // EXTERNALFILTER METHODS
+       //
+
+       @Override
+       protected String binary(Metadata metadata) {
+               return binary;
+       }
+
+       @Override
+       protected Iterable<String> parameters(Metadata metadata) {
+               ImmutableList.Builder<String> parameters = ImmutableList.builder();
+               /* the input file. */
+               parameters.add("--bits").add("16");
+               parameters.add("--channels").add(String.valueOf(metadata.channels()));
+               parameters.add("--encoding").add("signed-integer");
+               parameters.add("--rate").add(String.valueOf(metadata.frequency()));
+               parameters.add("--type").add("raw");
+               parameters.add("--endian").add("little");
+               parameters.add("-");
+               /* the output file. */
+               parameters.add("--bits").add("16");
+               parameters.add("--channels").add(String.valueOf(metadata.channels()));
+               parameters.add("--encoding").add("signed-integer");
+               parameters.add("--type").add("raw");
+               parameters.add("--endian").add("little");
+               parameters.add("-");
+               /* rate effect. */
+               parameters.add("rate").add("-h").add(String.valueOf(rate));
+               return parameters.build();
+       }
+
+}