Android MediaCodecVideoDecoder: Manage lifetime of texture frames

talk/app/webrtc/java/src/org/webrtc/VideoRenderer.java

 /*
  * libjingle
  * Copyright 2013 Google Inc.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are met:
  *
  *  1. Redistributions of source code must retain the above copyright notice,
  *     this list of conditions and the following disclaimer.
  *  2. Redistributions in binary form must reproduce the above copyright notice,
@@ skipping 26 matching lines @@
  */
 public class VideoRenderer {
 
   /** Java version of cricket::VideoFrame. Frames are only constructed from native code. */
   public static class I420Frame {
     public final int width;
     public final int height;
     public final int[] yuvStrides;
     public ByteBuffer[] yuvPlanes;
     public final boolean yuvFrame;
-    public Object textureObject;
+    // 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.
      */
     private 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.
+      samplingMatrix = new float[] {
+          1,  0, 0, 0,
+          0, -1, 0, 0,
+          0,  0, 1, 0,
+          0,  1, 0, 1};
     }
 
     /**
      * Construct a texture frame of the given dimensions with data in SurfaceTexture
      */
     private I420Frame(
         int width, int height, int rotationDegree,
-        Object textureObject, int textureId, long nativeFramePointer) {
+        int textureId, float[] samplingMatrix, long nativeFramePointer) {
       this.width = width;
       this.height = height;
       this.yuvStrides = null;
       this.yuvPlanes = null;
-      this.textureObject = textureObject;
+      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() {
@@ skipping 22 matching lines @@
     // 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.textureObject = null;
      frame.textureId = 0;
      if (frame.nativeFramePointer != 0) {
        releaseNativeFrame(frame.nativeFramePointer);
        frame.nativeFramePointer = 0;
      }
    }
 
   // |this| either wraps a native (GUI) renderer or a client-supplied Callbacks
   // (Java) implementation; this is indicated by |isWrappedVideoRenderer|.
   long nativeVideoRenderer;
@@ skipping 31 matching lines @@
   }
 
   private static native long nativeCreateGuiVideoRenderer(int x, int y);
   private static native long nativeWrapVideoRenderer(Callbacks callbacks);
 
   private static native void freeGuiVideoRenderer(long nativeVideoRenderer);
   private static native void freeWrappedVideoRenderer(long nativeVideoRenderer);
 
   private static native void releaseNativeFrame(long nativeFramePointer);
 }