webrtc/api/android/java/src/org/webrtc/VideoRenderer.java

/*
 *  Copyright 2013 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;

/**
 * Java version of VideoSinkInterface.  In addition to allowing clients to
 * define their own rendering behavior (by passing in a Callbacks object), this
 * class also provides a createGui() method for creating a GUI-rendering window
 * on various platforms.
 */
public class VideoRenderer {
  /**
   * Java version of cricket::VideoFrame. Frames are only constructed from native code and test
   * code.
   */
  public static class I420Frame {
    public final int width;
    public final int height;
    public final int[] yuvStrides;
    public ByteBuffer[] yuvPlanes;
    public final boolean yuvFrame;
    // Matrix that transforms standard coordinates to their proper sampling locations in
    // the texture. This transform compensates for any properties of the video source that
    // cause it to appear different from a normalized texture. This matrix does not take
    // |rotationDegree| into account.
    public final float[] samplingMatrix;
    public int textureId;
    // Frame pointer in C++.
    private long nativeFramePointer;

    // rotationDegree is the degree that the frame must be rotated clockwisely
    // to be rendered correctly.
    public int rotationDegree;

    /**
     * Construct a frame of the given dimensions with the specified planar data.
     */
    I420Frame(int width, int height, int rotationDegree, int[] yuvStrides, ByteBuffer[] yuvPlanes,
        long nativeFramePointer) {
      this.width = width;
      this.height = height;
      this.yuvStrides = yuvStrides;
      this.yuvPlanes = yuvPlanes;
      this.yuvFrame = true;
      this.rotationDegree = rotationDegree;
      this.nativeFramePointer = nativeFramePointer;
      if (rotationDegree % 90 != 0) {
        throw new IllegalArgumentException("Rotation degree not multiple of 90: " + rotationDegree);
      }
      // The convention in WebRTC is that the first element in a ByteBuffer corresponds to the
      // top-left corner of the image, but in glTexImage2D() the first element corresponds to the
      // bottom-left corner. This discrepancy is corrected by setting a vertical flip as sampling
      // matrix.
      // clang-format off
      samplingMatrix = new float[] {
          1,  0, 0, 0,
          0, -1, 0, 0,
          0,  0, 1, 0,
          0,  1, 0, 1};
      // clang-format on
    }

    /**
     * Construct a texture frame of the given dimensions with data in SurfaceTexture
     */
    I420Frame(int width, int height, int rotationDegree, int textureId, float[] samplingMatrix,
        long nativeFramePointer) {
      this.width = width;
      this.height = height;
      this.yuvStrides = null;
      this.yuvPlanes = null;
      this.samplingMatrix = samplingMatrix;
      this.textureId = textureId;
      this.yuvFrame = false;
      this.rotationDegree = rotationDegree;
      this.nativeFramePointer = nativeFramePointer;
      if (rotationDegree % 90 != 0) {
        throw new IllegalArgumentException("Rotation degree not multiple of 90: " + rotationDegree);
      }
    }

    public int rotatedWidth() {
      return (rotationDegree % 180 == 0) ? width : height;
    }

    public int rotatedHeight() {
      return (rotationDegree % 180 == 0) ? height : width;
    }

    @Override
    public String toString() {
      return width + "x" + height + ":" + yuvStrides[0] + ":" + yuvStrides[1] + ":" + yuvStrides[2];
    }
  }

  // Helper native function to do a video frame plane copying.
  public static native void nativeCopyPlane(
      ByteBuffer src, int width, int height, int srcStride, ByteBuffer dst, int dstStride);

  /** The real meat of VideoSinkInterface. */
  public static interface Callbacks {
    // |frame| might have pending rotation and implementation of Callbacks
    // should handle that by applying rotation during rendering. The callee
    // is responsible for signaling when it is done with |frame| by calling
    // renderFrameDone(frame).
    public void renderFrame(I420Frame frame);
  }

  /**
   * This must be called after every renderFrame() to release the frame.
   */
  public static void renderFrameDone(I420Frame frame) {
    frame.yuvPlanes = null;
    frame.textureId = 0;
    if (frame.nativeFramePointer != 0) {
      releaseNativeFrame(frame.nativeFramePointer);
      frame.nativeFramePointer = 0;
    }
  }

  long nativeVideoRenderer;

  public VideoRenderer(Callbacks callbacks) {
    nativeVideoRenderer = nativeWrapVideoRenderer(callbacks);
  }

  public void dispose() {
    if (nativeVideoRenderer == 0) {
      // Already disposed.
      return;
    }

    freeWrappedVideoRenderer(nativeVideoRenderer);
    nativeVideoRenderer = 0;
  }

  private static native long nativeWrapVideoRenderer(Callbacks callbacks);
  private static native void freeWrappedVideoRenderer(long nativeVideoRenderer);
  private static native void releaseNativeFrame(long nativeFramePointer);
}