Add texture support to HardwareVideoDecoder.

webrtc/sdk/android/src/java/org/webrtc/OesTextureBuffer.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 android.graphics.Matrix;
+import java.nio.ByteBuffer;
+import org.webrtc.VideoFrame.I420Buffer;
+import org.webrtc.VideoFrame.TextureBuffer;
+
+/** Android OES texture buffer. */
+class OesTextureBuffer implements TextureBuffer {

[sakal, 2017/07/17 13:44:56]

I think this class is inherently tied to SurfaceTextureHelper and should be a
subclass that can be created using a member method.

[mellem, 2017/07/17 21:57:15]

Moved this into SurfaceTextureHelper.  I'm not sure I like it from a code
organization perspective, but it does restrict it so it's only usable with the
right id and helper.

+  private final int id;
+  private final int width;
+  private final int height;
+  private final float[] transformMatrix;
+  private final SurfaceTextureHelper helper;
+  private int refCount;
+
+  OesTextureBuffer(
+      int id, int width, int height, float[] transformMatrix, SurfaceTextureHelper helper) {
+    this.id = id;
+    this.width = width;
+    this.height = height;
+    this.transformMatrix = transformMatrix;
+    this.helper = helper;
+    this.refCount = 1; // Creator implicitly holds a reference.
+  }
+
+  @Override
+  public TextureBuffer.Type getType() {
+    return TextureBuffer.Type.OES;
+  }
+
+  @Override
+  public int getTextureId() {
+    return id;
+  }
+
+  @Override
+  public int getWidth() {
+    return width;
+  }
+
+  @Override
+  public int getHeight() {
+    return height;
+  }
+
+  @Override
+  public I420Buffer toI420() {
+    // SurfaceTextureHelper requires a stride that is divisible by 8.  Round width up.
+    // See SurfaceTextureHelper for details on the size and format.
+    int stride = ((width + 7) / 8) * 8;
+    int uvHeight = (height + 1) / 2;
+    // Due to the layout used by SurfaceTextureHelper, vPos + stride * uvHeight would overrun the
+    // buffer.  Add one row at the bottom to compensate for this.  There will never be data in the
+    // extra row, but now other code does not have to deal with v stride * v height exceeding the
+    // buffer's capacity.
+    int size = stride * (height + uvHeight + 1);
+    ByteBuffer buffer = ByteBuffer.allocateDirect(size);
+    helper.textureToYUV(buffer, width, height, stride, id, transformMatrix);
+
+    int yPos = 0;
+    int uPos = yPos + stride * height;
+    // Rows of U and V alternate in the buffer, so V data starts after the first row of U.
+    int vPos = yPos + stride / 2;
+
+    // SurfaceTextureHelper uses the same stride for Y, U, and V data.
+    return new I420BufferImpl(
+        buffer, width, height, yPos, stride, uPos, stride, vPos, stride, null);
+  }
+
+  @Override
+  public void retain() {
+    ++refCount;
+  }
+
+  @Override
+  public void release() {
+    if (--refCount == 0) {
+      helper.returnTextureFrame();
+    }
+  }
+}