Optimize HardwareVideoDecoder by doing all frame conversions in C++.

webrtc/sdk/android/src/java/org/webrtc/NV12Buffer.java

+/*
+ * Copyright 2017 The WebRTC project authors. All Rights Reserved.
+ *
+ * Use of this source code is governed by a BSD-style license
+ * that can be found in the LICENSE file in the root of the source
+ * tree. An additional intellectual property rights grant can be found
+ * in the file PATENTS.  All contributing project authors may
+ * be found in the AUTHORS file in the root of the source tree.
+ */
+
+package org.webrtc;
+
+import java.nio.ByteBuffer;
+
+public class NV12Buffer implements VideoFrame.Buffer {
+  private final int width;
+  private final int height;
+  private final int stride;
+  private final int sliceHeight;
+  private final ByteBuffer buffer;
+  private final Runnable releaseCallback;
+
+  private int refCount;
+
+  public NV12Buffer(int width, int height, int stride, int sliceHeight, ByteBuffer buffer,
+      Runnable releaseCallback) {
+    this.width = width;
+    this.height = height;
+    this.stride = stride;
+    this.sliceHeight = sliceHeight;
+    this.buffer = buffer;
+    this.releaseCallback = releaseCallback;
+
+    refCount = 1;
+  }
+
+  @Override
+  public int getWidth() {
+    return width;
+  }
+
+  @Override
+  public int getHeight() {
+    return height;
+  }
+
+  @Override
+  public VideoFrame.I420Buffer toI420() {
+    return (VideoFrame.I420Buffer) cropAndScale(0, 0, width, height, width, height);
+  }
+
+  @Override
+  public void retain() {
+    refCount++;
+  }
+
+  @Override
+  public void release() {
+    if (--refCount == 0) {
+      releaseCallback.run();
+    }
+  }
+
+  @Override
+  public VideoFrame.Buffer cropAndScale(
+      int cropX, int cropY, int cropWidth, int cropHeight, int scaleWidth, int scaleHeight) {
+    I420BufferImpl newBuffer = I420BufferImpl.allocate(scaleWidth, scaleHeight);
+    nativeCropAndScale(cropX, cropY, cropWidth, cropHeight, scaleWidth, scaleHeight, buffer, width,
+        height, stride, sliceHeight, newBuffer.getDataY(), newBuffer.getStrideY(),
+        newBuffer.getDataU(), newBuffer.getStrideU(), newBuffer.getDataV(), newBuffer.getStrideV());
+    return newBuffer;
+  }
+
+  private static native void nativeCropAndScale(int cropX, int cropY, int cropWidth, int cropHeight,
+      int scaleWidth, int scaleHeight, ByteBuffer src, int srcWidth, int srcHeight, int srcStride,
+      int srcSliceHeight, ByteBuffer dstY, int dstStrideY, ByteBuffer dstU, int dstStrideU,
+      ByteBuffer dstV, int dstStrideV);
+}