[audio] Move WhisperTranslator to audio extension

examples/src/main/java/ai/djl/examples/inference/whisper/WhisperModel.java

@@ -13,6 +13,7 @@
 package ai.djl.examples.inference.whisper;
 
 import ai.djl.ModelException;
+import ai.djl.audio.translator.WhisperTranslatorFactory;
 import ai.djl.inference.Predictor;
 import ai.djl.modality.audio.Audio;
 import ai.djl.modality.audio.AudioFactory;
@@ -37,7 +38,7 @@ public WhisperModel() throws ModelException, IOException {
                         .optModelUrls(
                                 "https://resources.djl.ai/demo/pytorch/whisper/whisper_en.zip")
                         .optEngine("PyTorch")
-                        .optTranslator(new WhisperTranslator())
+                        .optTranslatorFactory(new WhisperTranslatorFactory())
                         .build();
         whisperModel = criteria.loadModel();
     }

examples/src/main/java/ai/djl/examples/inference/whisper/WhisperTranslator.java → extensions/audio/src/main/java/ai/djl/audio/translator/WhisperTranslator.java

@@ -10,7 +10,7 @@
  * OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions
  * and limitations under the License.
  */
-package ai.djl.examples.inference.whisper;
+package ai.djl.audio.translator;
 
 import ai.djl.audio.processor.AudioProcessor;
 import ai.djl.audio.processor.LogMelSpectrogram;
@@ -22,6 +22,7 @@
 import ai.djl.ndarray.NDList;
 import ai.djl.ndarray.NDManager;
 import ai.djl.translate.NoBatchifyTranslator;
+import ai.djl.translate.Translator;
 import ai.djl.translate.TranslatorContext;
 import ai.djl.util.JsonUtils;
 
@@ -37,11 +38,16 @@
 import java.util.List;
 import java.util.Map;
 
+/**
+ * A {@link Translator} that process the {@link Audio} into {@link String} to get a text translation
+ * of the audio.
+ */
 public class WhisperTranslator implements NoBatchifyTranslator<Audio, String> {
 
     private List<AudioProcessor> processors;
     private Vocabulary vocabulary;
 
+    /** Constructs a new instance of {@code WhisperTranslator}. */
     public WhisperTranslator() {
         processors = new ArrayList<>();
     }

extensions/audio/src/main/java/ai/djl/audio/translator/WhisperTranslatorFactory.java

@@ -0,0 +1,54 @@
+/*
+ * Copyright 2022 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"). You may not use this file except in compliance
+ * with the License. A copy of the License is located at
+ *
+ * http://aws.amazon.com/apache2.0/
+ *
+ * or in the "license" file accompanying this file. This file is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES
+ * OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions
+ * and limitations under the License.
+ */
+package ai.djl.audio.translator;
+
+import ai.djl.Model;
+import ai.djl.modality.audio.Audio;
+import ai.djl.translate.Translator;
+import ai.djl.translate.TranslatorFactory;
+import ai.djl.util.Pair;
+
+import java.io.Serializable;
+import java.lang.reflect.Type;
+import java.util.HashSet;
+import java.util.Map;
+import java.util.Set;
+
+/** A {@link TranslatorFactory} that creates a {@link WhisperTranslator} instance. */
+public class WhisperTranslatorFactory implements TranslatorFactory, Serializable {
+
+    private static final long serialVersionUID = 1L;
+
+    private static final Set<Pair<Type, Type>> SUPPORTED_TYPES = new HashSet<>();
+
+    static {
+        SUPPORTED_TYPES.add(new Pair<>(Audio.class, String.class));
+    }
+
+    /** {@inheritDoc} */
+    @Override
+    public Set<Pair<Type, Type>> getSupportedTypes() {
+        return SUPPORTED_TYPES;
+    }
+
+    /** {@inheritDoc} */
+    @Override
+    @SuppressWarnings("unchecked")
+    public <I, O> Translator<I, O> newInstance(
+            Class<I> input, Class<O> output, Model model, Map<String, ?> arguments) {
+        if (input == Audio.class && output == String.class) {
+            return (Translator<I, O>) new WhisperTranslator();
+        }
+        throw new IllegalArgumentException("Unsupported input/output types.");
+    }
+}