1 files changed, 134 insertions, 0 deletions
diff --git a/mobile/android/exoplayer2/src/main/java/org/mozilla/thirdparty/com/google/android/exoplayer2/audio/ResamplingAudioProcessor.java b/mobile/android/exoplayer2/src/main/java/org/mozilla/thirdparty/com/google/android/exoplayer2/audio/ResamplingAudioProcessor.java
new file mode 100644
index 0000000000..efd8a30d61
--- /dev/null
+++ b/mobile/android/exoplayer2/src/main/java/org/mozilla/thirdparty/com/google/android/exoplayer2/audio/ResamplingAudioProcessor.java
@@ -0,0 +1,134 @@
+/*
+ * Copyright (C) 2017 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License 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 org.mozilla.thirdparty.com.google.android.exoplayer2.audio;
+
+import org.mozilla.thirdparty.com.google.android.exoplayer2.C;
+import org.mozilla.thirdparty.com.google.android.exoplayer2.Format;
+import java.nio.ByteBuffer;
+
+/**
+ * An {@link AudioProcessor} that converts different PCM audio encodings to 16-bit integer PCM. The
+ * following encodings are supported as input:
+ *
+ * <ul>
+ *   <li>{@link C#ENCODING_PCM_8BIT}
+ *   <li>{@link C#ENCODING_PCM_16BIT} ({@link #isActive()} will return {@code false})
+ *   <li>{@link C#ENCODING_PCM_16BIT_BIG_ENDIAN}
+ *   <li>{@link C#ENCODING_PCM_24BIT}
+ *   <li>{@link C#ENCODING_PCM_32BIT}
+ *   <li>{@link C#ENCODING_PCM_FLOAT}
+ * </ul>
+ */
+/* package */ final class ResamplingAudioProcessor extends BaseAudioProcessor {
+
+  @Override
+  public AudioFormat onConfigure(AudioFormat inputAudioFormat)
+      throws UnhandledAudioFormatException {
+    @C.PcmEncoding int encoding = inputAudioFormat.encoding;
+    if (encoding != C.ENCODING_PCM_8BIT
+        && encoding != C.ENCODING_PCM_16BIT
+        && encoding != C.ENCODING_PCM_16BIT_BIG_ENDIAN
+        && encoding != C.ENCODING_PCM_24BIT
+        && encoding != C.ENCODING_PCM_32BIT
+        && encoding != C.ENCODING_PCM_FLOAT) {
+      throw new UnhandledAudioFormatException(inputAudioFormat);
+    }
+    return encoding != C.ENCODING_PCM_16BIT
+        ? new AudioFormat(
+            inputAudioFormat.sampleRate, inputAudioFormat.channelCount, C.ENCODING_PCM_16BIT)
+        : AudioFormat.NOT_SET;
+  }
+
+  @Override
+  public void queueInput(ByteBuffer inputBuffer) {
+    // Prepare the output buffer.
+    int position = inputBuffer.position();
+    int limit = inputBuffer.limit();
+    int size = limit - position;
+    int resampledSize;
+    switch (inputAudioFormat.encoding) {
+      case C.ENCODING_PCM_8BIT:
+        resampledSize = size * 2;
+        break;
+      case C.ENCODING_PCM_16BIT_BIG_ENDIAN:
+        resampledSize = size;
+        break;
+      case C.ENCODING_PCM_24BIT:
+        resampledSize = (size / 3) * 2;
+        break;
+      case C.ENCODING_PCM_32BIT:
+      case C.ENCODING_PCM_FLOAT:
+        resampledSize = size / 2;
+        break;
+      case C.ENCODING_PCM_16BIT:
+      case C.ENCODING_INVALID:
+      case Format.NO_VALUE:
+      default:
+        throw new IllegalStateException();
+    }
+
+    // Resample the little endian input and update the input/output buffers.
+    ByteBuffer buffer = replaceOutputBuffer(resampledSize);
+    switch (inputAudioFormat.encoding) {
+      case C.ENCODING_PCM_8BIT:
+        // 8 -> 16 bit resampling. Shift each byte from [0, 256) to [-128, 128) and scale up.
+        for (int i = position; i < limit; i++) {
+          buffer.put((byte) 0);
+          buffer.put((byte) ((inputBuffer.get(i) & 0xFF) - 128));
+        }
+        break;
+      case C.ENCODING_PCM_16BIT_BIG_ENDIAN:
+        // Big endian to little endian resampling. Swap the byte order.
+        for (int i = position; i < limit; i += 2) {
+          buffer.put(inputBuffer.get(i + 1));
+          buffer.put(inputBuffer.get(i));
+        }
+        break;
+      case C.ENCODING_PCM_24BIT:
+        // 24 -> 16 bit resampling. Drop the least significant byte.
+        for (int i = position; i < limit; i += 3) {
+          buffer.put(inputBuffer.get(i + 1));
+          buffer.put(inputBuffer.get(i + 2));
+        }
+        break;
+      case C.ENCODING_PCM_32BIT:
+        // 32 -> 16 bit resampling. Drop the two least significant bytes.
+        for (int i = position; i < limit; i += 4) {
+          buffer.put(inputBuffer.get(i + 2));
+          buffer.put(inputBuffer.get(i + 3));
+        }
+        break;
+      case C.ENCODING_PCM_FLOAT:
+        // 32 bit floating point -> 16 bit resampling. Floating point values are in the range
+        // [-1.0, 1.0], so need to be scaled by Short.MAX_VALUE.
+        for (int i = position; i < limit; i += 4) {
+          short value = (short) (inputBuffer.getFloat(i) * Short.MAX_VALUE);
+          buffer.put((byte) (value & 0xFF));
+          buffer.put((byte) ((value >> 8) & 0xFF));
+        }
+        break;
+      case C.ENCODING_PCM_16BIT:
+      case C.ENCODING_INVALID:
+      case Format.NO_VALUE:
+      default:
+        // Never happens.
+        throw new IllegalStateException();
+    }
+    inputBuffer.position(inputBuffer.limit());
+    buffer.flip();
+  }
+
+}