1 files changed, 109 insertions, 0 deletions
diff --git a/mobile/android/exoplayer2/src/main/java/org/mozilla/thirdparty/com/google/android/exoplayer2/audio/FloatResamplingAudioProcessor.java b/mobile/android/exoplayer2/src/main/java/org/mozilla/thirdparty/com/google/android/exoplayer2/audio/FloatResamplingAudioProcessor.java
new file mode 100644
index 0000000000..c2eb62a0ad
--- /dev/null
+++ b/mobile/android/exoplayer2/src/main/java/org/mozilla/thirdparty/com/google/android/exoplayer2/audio/FloatResamplingAudioProcessor.java
@@ -0,0 +1,109 @@
+/*
+ * Copyright (C) 2018 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 org.mozilla.thirdparty.com.google.android.exoplayer2.util.Util;
+import java.nio.ByteBuffer;
+
+/**
+ * An {@link AudioProcessor} that converts high resolution PCM audio to 32-bit float. The following
+ * encodings are supported as input:
+ *
+ * <ul>
+ *   <li>{@link C#ENCODING_PCM_24BIT}
+ *   <li>{@link C#ENCODING_PCM_32BIT}
+ *   <li>{@link C#ENCODING_PCM_FLOAT} ({@link #isActive()} will return {@code false})
+ * </ul>
+ */
+/* package */ final class FloatResamplingAudioProcessor extends BaseAudioProcessor {
+
+  private static final int FLOAT_NAN_AS_INT = Float.floatToIntBits(Float.NaN);
+  private static final double PCM_32_BIT_INT_TO_PCM_32_BIT_FLOAT_FACTOR = 1.0 / 0x7FFFFFFF;
+
+  @Override
+  public AudioFormat onConfigure(AudioFormat inputAudioFormat)
+      throws UnhandledAudioFormatException {
+    @C.PcmEncoding int encoding = inputAudioFormat.encoding;
+    if (!Util.isEncodingHighResolutionPcm(encoding)) {
+      throw new UnhandledAudioFormatException(inputAudioFormat);
+    }
+    return encoding != C.ENCODING_PCM_FLOAT
+        ? new AudioFormat(
+            inputAudioFormat.sampleRate, inputAudioFormat.channelCount, C.ENCODING_PCM_FLOAT)
+        : AudioFormat.NOT_SET;
+  }
+
+  @Override
+  public void queueInput(ByteBuffer inputBuffer) {
+    int position = inputBuffer.position();
+    int limit = inputBuffer.limit();
+    int size = limit - position;
+
+    ByteBuffer buffer;
+    switch (inputAudioFormat.encoding) {
+      case C.ENCODING_PCM_24BIT:
+        buffer = replaceOutputBuffer((size / 3) * 4);
+        for (int i = position; i < limit; i += 3) {
+          int pcm32BitInteger =
+              ((inputBuffer.get(i) & 0xFF) << 8)
+                  | ((inputBuffer.get(i + 1) & 0xFF) << 16)
+                  | ((inputBuffer.get(i + 2) & 0xFF) << 24);
+          writePcm32BitFloat(pcm32BitInteger, buffer);
+        }
+        break;
+      case C.ENCODING_PCM_32BIT:
+        buffer = replaceOutputBuffer(size);
+        for (int i = position; i < limit; i += 4) {
+          int pcm32BitInteger =
+              (inputBuffer.get(i) & 0xFF)
+                  | ((inputBuffer.get(i + 1) & 0xFF) << 8)
+                  | ((inputBuffer.get(i + 2) & 0xFF) << 16)
+                  | ((inputBuffer.get(i + 3) & 0xFF) << 24);
+          writePcm32BitFloat(pcm32BitInteger, buffer);
+        }
+        break;
+      case C.ENCODING_PCM_8BIT:
+      case C.ENCODING_PCM_16BIT:
+      case C.ENCODING_PCM_16BIT_BIG_ENDIAN:
+      case C.ENCODING_PCM_FLOAT:
+      case C.ENCODING_INVALID:
+      case Format.NO_VALUE:
+      default:
+        // Never happens.
+        throw new IllegalStateException();
+    }
+
+    inputBuffer.position(inputBuffer.limit());
+    buffer.flip();
+  }
+
+  /**
+   * Converts the provided 32-bit integer to a 32-bit float value and writes it to {@code buffer}.
+   *
+   * @param pcm32BitInt The 32-bit integer value to convert to 32-bit float in [-1.0, 1.0].
+   * @param buffer The output buffer.
+   */
+  private static void writePcm32BitFloat(int pcm32BitInt, ByteBuffer buffer) {
+    float pcm32BitFloat = (float) (PCM_32_BIT_INT_TO_PCM_32_BIT_FLOAT_FACTOR * pcm32BitInt);
+    int floatBits = Float.floatToIntBits(pcm32BitFloat);
+    if (floatBits == FLOAT_NAN_AS_INT) {
+      floatBits = Float.floatToIntBits((float) 0.0);
+    }
+    buffer.putInt(floatBits);
+  }
+}