talk/app/webrtc/java/android/org/webrtc/SurfaceTextureHelper.java - platform/external/webrtc - Git at Google

 /*
  * libjingle
  * Copyright 2015 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,
  *     this list of conditions and the following disclaimer in the documentation
  *     and/or other materials provided with the distribution.
  *  3. The name of the author may not be used to endorse or promote products
  *     derived from this software without specific prior written permission.
  *
  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
  * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
  * EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
  * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
  * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
  * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
  * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */

 package org.webrtc;

 import android.graphics.SurfaceTexture;
 import android.opengl.GLES11Ext;
 import android.opengl.GLES20;
 import android.os.Build;
 import android.os.Handler;
 import android.os.HandlerThread;
 import android.os.SystemClock;

 import java.nio.ByteBuffer;
 import java.nio.FloatBuffer;
 import java.util.concurrent.Callable;
 import java.util.concurrent.CountDownLatch;
 import java.util.concurrent.TimeUnit;

 /**
  * Helper class to create and synchronize access to a SurfaceTexture. The caller will get notified
  * of new frames in onTextureFrameAvailable(), and should call returnTextureFrame() when done with
  * the frame. Only one texture frame can be in flight at once, so returnTextureFrame() must be
  * called in order to receive a new frame. Call disconnect() to stop receiveing new frames and
  * release all resources.
  * Note that there is a C++ counter part of this class that optionally can be used. It is used for
  * wrapping texture frames into webrtc::VideoFrames and also handles calling returnTextureFrame()
  * when the webrtc::VideoFrame is no longer used.
  */
 class SurfaceTextureHelper {
   private static final String TAG = "SurfaceTextureHelper";
   /**
    * Callback interface for being notified that a new texture frame is available. The calls will be
    * made on a dedicated thread with a bound EGLContext. The thread will be the same throughout the
    * lifetime of the SurfaceTextureHelper instance, but different from the thread calling the
    * SurfaceTextureHelper constructor. The callee is not allowed to make another EGLContext current
    * on the calling thread.
    */
   public interface OnTextureFrameAvailableListener {
     abstract void onTextureFrameAvailable(
         int oesTextureId, float[] transformMatrix, long timestampNs);
   }

   public static SurfaceTextureHelper create(EglBase.Context sharedContext) {
     return create(sharedContext, null);
   }

   /**
    * Construct a new SurfaceTextureHelper sharing OpenGL resources with |sharedContext|. If
    * |handler| is non-null, the callback will be executed on that handler's thread. If |handler| is
    * null, a dedicated private thread is created for the callbacks.
    */
   public static SurfaceTextureHelper create(final EglBase.Context sharedContext,
       final Handler handler) {
     final Handler finalHandler;
     if (handler != null) {
       finalHandler = handler;
     } else {
       final HandlerThread thread = new HandlerThread(TAG);
       thread.start();
       finalHandler = new Handler(thread.getLooper());
     }
     // The onFrameAvailable() callback will be executed on the SurfaceTexture ctor thread. See:
     // http://grepcode.com/file/repository.grepcode.com/java/ext/com.google.android/android/5.1.1_r1/android/graphics/SurfaceTexture.java#195.
     // Therefore, in order to control the callback thread on API lvl < 21, the SurfaceTextureHelper
     // is constructed on the |handler| thread.
     return ThreadUtils.invokeUninterruptibly(finalHandler, new Callable<SurfaceTextureHelper>() {
       @Override public SurfaceTextureHelper call() {
         return new SurfaceTextureHelper(sharedContext, finalHandler, (handler == null));
       }
     });
   }

   // State for YUV conversion, instantiated on demand.
   static private class YuvConverter {
     private final EglBase eglBase;
     private final GlShader shader;
     private boolean released = false;

     // Vertex coordinates in Normalized Device Coordinates, i.e.
     // (-1, -1) is bottom-left and (1, 1) is top-right.
     private static final FloatBuffer DEVICE_RECTANGLE =
         GlUtil.createFloatBuffer(new float[] {
               -1.0f, -1.0f,  // Bottom left.
                1.0f, -1.0f,  // Bottom right.
               -1.0f,  1.0f,  // Top left.
                1.0f,  1.0f,  // Top right.
             });

     // Texture coordinates - (0, 0) is bottom-left and (1, 1) is top-right.
     private static final FloatBuffer TEXTURE_RECTANGLE =
         GlUtil.createFloatBuffer(new float[] {
               0.0f, 0.0f,  // Bottom left.
               1.0f, 0.0f,  // Bottom right.
               0.0f, 1.0f,  // Top left.
               1.0f, 1.0f   // Top right.
             });

     private static final String VERTEX_SHADER =
         "varying vec2 interp_tc;\n"
       + "attribute vec4 in_pos;\n"
       + "attribute vec4 in_tc;\n"
       + "\n"
       + "uniform mat4 texMatrix;\n"
       + "\n"
       + "void main() {\n"
       + "    gl_Position = in_pos;\n"
       + "    interp_tc = (texMatrix * in_tc).xy;\n"
       + "}\n";

     private static final String FRAGMENT_SHADER =
         "#extension GL_OES_EGL_image_external : require\n"
       + "precision mediump float;\n"
       + "varying vec2 interp_tc;\n"
       + "\n"
       + "uniform samplerExternalOES oesTex;\n"
       // Difference in texture coordinate corresponding to one
       // sub-pixel in the x direction.
       + "uniform vec2 xUnit;\n"
       // Color conversion coefficients, including constant term
       + "uniform vec4 coeffs;\n"
       + "\n"
       + "void main() {\n"
       // Since the alpha read from the texture is always 1, this could
       // be written as a mat4 x vec4 multiply. However, that seems to
       // give a worse framerate, possibly because the additional
       // multiplies by 1.0 consume resources. TODO(nisse): Could also
       // try to do it as a vec3 x mat3x4, followed by an add in of a
       // constant vector.
       + "  gl_FragColor.r = coeffs.a + dot(coeffs.rgb,\n"
       + "      texture2D(oesTex, interp_tc - 1.5 * xUnit).rgb);\n"
       + "  gl_FragColor.g = coeffs.a + dot(coeffs.rgb,\n"
       + "      texture2D(oesTex, interp_tc - 0.5 * xUnit).rgb);\n"
       + "  gl_FragColor.b = coeffs.a + dot(coeffs.rgb,\n"
       + "      texture2D(oesTex, interp_tc + 0.5 * xUnit).rgb);\n"
       + "  gl_FragColor.a = coeffs.a + dot(coeffs.rgb,\n"
       + "      texture2D(oesTex, interp_tc + 1.5 * xUnit).rgb);\n"
       + "}\n";

     private int texMatrixLoc;
     private int xUnitLoc;
     private int coeffsLoc;;

     YuvConverter (EglBase.Context sharedContext) {
       eglBase = EglBase.create(sharedContext, EglBase.CONFIG_PIXEL_RGBA_BUFFER);
       eglBase.createDummyPbufferSurface();
       eglBase.makeCurrent();

       shader = new GlShader(VERTEX_SHADER, FRAGMENT_SHADER);
       shader.useProgram();
       texMatrixLoc = shader.getUniformLocation("texMatrix");
       xUnitLoc = shader.getUniformLocation("xUnit");
       coeffsLoc = shader.getUniformLocation("coeffs");
       GLES20.glUniform1i(shader.getUniformLocation("oesTex"), 0);
       GlUtil.checkNoGLES2Error("Initialize fragment shader uniform values.");
       // Initialize vertex shader attributes.
       shader.setVertexAttribArray("in_pos", 2, DEVICE_RECTANGLE);
       // If the width is not a multiple of 4 pixels, the texture
       // will be scaled up slightly and clipped at the right border.
       shader.setVertexAttribArray("in_tc", 2, TEXTURE_RECTANGLE);
       eglBase.detachCurrent();
     }

     synchronized void convert(ByteBuffer buf,
         int width, int height, int stride, int textureId, float [] transformMatrix) {
       if (released) {
         throw new IllegalStateException(
             "YuvConverter.convert called on released object");
       }

       // We draw into a buffer laid out like
       //
       //    +---------+
       //    |         |
       //    |  Y      |
       //    |         |
       //    |         |
       //    +----+----+
       //    | U  | V  |
       //    |    |    |
       //    +----+----+
       //
       // In memory, we use the same stride for all of Y, U and V. The
       // U data starts at offset |height| * |stride| from the Y data,
       // and the V data starts at at offset |stride/2| from the U
       // data, with rows of U and V data alternating.
       //
       // Now, it would have made sense to allocate a pixel buffer with
       // a single byte per pixel (EGL10.EGL_COLOR_BUFFER_TYPE,
       // EGL10.EGL_LUMINANCE_BUFFER,), but that seems to be
       // unsupported by devices. So do the following hack: Allocate an
       // RGBA buffer, of width |stride|/4. To render each of these
       // large pixels, sample the texture at 4 different x coordinates
       // and store the results in the four components.
       //
       // Since the V data needs to start on a boundary of such a
       // larger pixel, it is not sufficient that |stride| is even, it
       // has to be a multiple of 8 pixels.

       if (stride % 8 != 0) {
         throw new IllegalArgumentException(
             "Invalid stride, must be a multiple of 8");
       }
       if (stride < width){
         throw new IllegalArgumentException(
             "Invalid stride, must >= width");
       }

       int y_width = (width+3) / 4;
       int uv_width = (width+7) / 8;
       int uv_height = (height+1)/2;
       int total_height = height + uv_height;
       int size = stride * total_height;

       if (buf.capacity() < size) {
         throw new IllegalArgumentException("YuvConverter.convert called with too small buffer");
       }
       // Produce a frame buffer starting at top-left corner, not
       // bottom-left.
       transformMatrix =
           RendererCommon.multiplyMatrices(transformMatrix,
               RendererCommon.verticalFlipMatrix());

       // Create new pBuffferSurface with the correct size if needed.
       if (eglBase.hasSurface()) {
         if (eglBase.surfaceWidth() != stride/4 ||
             eglBase.surfaceHeight() != total_height){
           eglBase.releaseSurface();
           eglBase.createPbufferSurface(stride/4, total_height);
         }
       } else {
         eglBase.createPbufferSurface(stride/4, total_height);
       }

       eglBase.makeCurrent();

       GLES20.glActiveTexture(GLES20.GL_TEXTURE0);
       GLES20.glBindTexture(GLES11Ext.GL_TEXTURE_EXTERNAL_OES, textureId);
       GLES20.glUniformMatrix4fv(texMatrixLoc, 1, false, transformMatrix, 0);

       // Draw Y
       GLES20.glViewport(0, 0, y_width, height);
       // Matrix * (1;0;0;0) / width. Note that opengl uses column major order.
       GLES20.glUniform2f(xUnitLoc,
           transformMatrix[0] / width,
           transformMatrix[1] / width);
       // Y'UV444 to RGB888, see
       // https://en.wikipedia.org/wiki/YUV#Y.27UV444_to_RGB888_conversion.
       // We use the ITU-R coefficients for U and V */
       GLES20.glUniform4f(coeffsLoc, 0.299f, 0.587f, 0.114f, 0.0f);
       GLES20.glDrawArrays(GLES20.GL_TRIANGLE_STRIP, 0, 4);

       // Draw U
       GLES20.glViewport(0, height, uv_width, uv_height);
       // Matrix * (1;0;0;0) / (2*width). Note that opengl uses column major order.
       GLES20.glUniform2f(xUnitLoc,
           transformMatrix[0] / (2.0f*width),
           transformMatrix[1] / (2.0f*width));
       GLES20.glUniform4f(coeffsLoc, -0.169f, -0.331f, 0.499f, 0.5f);
       GLES20.glDrawArrays(GLES20.GL_TRIANGLE_STRIP, 0, 4);

       // Draw V
       GLES20.glViewport(stride/8, height, uv_width, uv_height);
       GLES20.glUniform4f(coeffsLoc, 0.499f, -0.418f, -0.0813f, 0.5f);
       GLES20.glDrawArrays(GLES20.GL_TRIANGLE_STRIP, 0, 4);

       GLES20.glReadPixels(0, 0, stride/4, total_height, GLES20.GL_RGBA,
           GLES20.GL_UNSIGNED_BYTE, buf);

       GlUtil.checkNoGLES2Error("YuvConverter.convert");

       // Unbind texture. Reportedly needed on some devices to get
       // the texture updated from the camera.
       GLES20.glBindTexture(GLES11Ext.GL_TEXTURE_EXTERNAL_OES, 0);
       eglBase.detachCurrent();
     }

     synchronized void release() {
       released = true;
       eglBase.makeCurrent();
       shader.release();
       eglBase.release();
     }
   }

   private final Handler handler;
   private boolean isOwningThread;
   private final EglBase eglBase;
   private final SurfaceTexture surfaceTexture;
   private final int oesTextureId;
   private YuvConverter yuvConverter;

   private OnTextureFrameAvailableListener listener;
   // The possible states of this class.
   private boolean hasPendingTexture = false;
   private boolean isTextureInUse = false;
   private boolean isQuitting = false;

   private SurfaceTextureHelper(EglBase.Context sharedContext,
       Handler handler, boolean isOwningThread) {
     if (handler.getLooper().getThread() != Thread.currentThread()) {
       throw new IllegalStateException("SurfaceTextureHelper must be created on the handler thread");
     }
     this.handler = handler;
     this.isOwningThread = isOwningThread;

     eglBase = EglBase.create(sharedContext, EglBase.CONFIG_PIXEL_BUFFER);
     eglBase.createDummyPbufferSurface();
     eglBase.makeCurrent();

     oesTextureId = GlUtil.generateTexture(GLES11Ext.GL_TEXTURE_EXTERNAL_OES);
     surfaceTexture = new SurfaceTexture(oesTextureId);
   }

   private YuvConverter getYuvConverter() {
     // yuvConverter is assigned once
     if (yuvConverter != null)
       return yuvConverter;

     synchronized(this) {
       if (yuvConverter == null)
         yuvConverter = new YuvConverter(eglBase.getEglBaseContext());
       return yuvConverter;
     }
   }

   /**
    *  Start to stream textures to the given |listener|.
    *  A Listener can only be set once.
    */
   public void setListener(OnTextureFrameAvailableListener listener) {
     if (this.listener != null) {
       throw new IllegalStateException("SurfaceTextureHelper listener has already been set.");
     }
     this.listener = listener;
     surfaceTexture.setOnFrameAvailableListener(new SurfaceTexture.OnFrameAvailableListener() {
       @Override
       public void onFrameAvailable(SurfaceTexture surfaceTexture) {
         hasPendingTexture = true;
         tryDeliverTextureFrame();
       }
     });
   }

   /**
    * Retrieve the underlying SurfaceTexture. The SurfaceTexture should be passed in to a video
    * producer such as a camera or decoder.
    */
   public SurfaceTexture getSurfaceTexture() {
     return surfaceTexture;
   }

   /**
    * Call this function to signal that you are done with the frame received in
    * onTextureFrameAvailable(). Only one texture frame can be in flight at once, so you must call
    * this function in order to receive a new frame.
    */
   public void returnTextureFrame() {
     handler.post(new Runnable() {
       @Override public void run() {
         isTextureInUse = false;
         if (isQuitting) {
           release();
         } else {
           tryDeliverTextureFrame();
         }
       }
     });
   }

   /**
    * Call disconnect() to stop receiving frames. Resources are released when the texture frame has
    * been returned by a call to returnTextureFrame(). You are guaranteed to not receive any more
    * onTextureFrameAvailable() after this function returns.
    */
   public void disconnect() {
     if (!isOwningThread) {
       throw new IllegalStateException("Must call disconnect(handler).");
     }
     if (handler.getLooper().getThread() == Thread.currentThread()) {
       isQuitting = true;
       if (!isTextureInUse) {
         release();
       }
       return;
     }
     final CountDownLatch barrier = new CountDownLatch(1);
     handler.postAtFrontOfQueue(new Runnable() {
       @Override public void run() {
         isQuitting = true;
         barrier.countDown();
         if (!isTextureInUse) {
           release();
         }
       }
     });
     ThreadUtils.awaitUninterruptibly(barrier);
   }

   /**
    * Call disconnect() to stop receiving frames and quit the looper used by |handler|.
    * Resources are released when the texture frame has been returned by a call to
    * returnTextureFrame(). You are guaranteed to not receive any more
    * onTextureFrameAvailable() after this function returns.
    */
   public void disconnect(Handler handler) {
     if (this.handler != handler) {
       throw new IllegalStateException("Wrong handler.");
     }
     isOwningThread = true;
     disconnect();
   }

   public void textureToYUV(ByteBuffer buf,
       int width, int height, int stride, int textureId, float [] transformMatrix) {
     if (textureId != oesTextureId)
       throw new IllegalStateException("textureToByteBuffer called with unexpected textureId");

     getYuvConverter().convert(buf, width, height, stride, textureId, transformMatrix);
   }

   private void tryDeliverTextureFrame() {
     if (handler.getLooper().getThread() != Thread.currentThread()) {
       throw new IllegalStateException("Wrong thread.");
     }
     if (isQuitting || !hasPendingTexture || isTextureInUse) {
       return;
     }
     isTextureInUse = true;
     hasPendingTexture = false;

     eglBase.makeCurrent();
     surfaceTexture.updateTexImage();

     final float[] transformMatrix = new float[16];
     surfaceTexture.getTransformMatrix(transformMatrix);
     final long timestampNs = (Build.VERSION.SDK_INT >= Build.VERSION_CODES.ICE_CREAM_SANDWICH)
         ? surfaceTexture.getTimestamp()
         : TimeUnit.MILLISECONDS.toNanos(SystemClock.elapsedRealtime());
     listener.onTextureFrameAvailable(oesTextureId, transformMatrix, timestampNs);
   }

   private void release() {
     if (handler.getLooper().getThread() != Thread.currentThread()) {
       throw new IllegalStateException("Wrong thread.");
     }
     if (isTextureInUse || !isQuitting) {
       throw new IllegalStateException("Unexpected release.");
     }
     synchronized (this) {
       if (yuvConverter != null)
         yuvConverter.release();
     }
     eglBase.makeCurrent();
     GLES20.glDeleteTextures(1, new int[] {oesTextureId}, 0);
     surfaceTexture.release();
     eglBase.release();
     handler.getLooper().quit();
   }
 }
	/*
	* libjingle
	* Copyright 2015 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,
	* this list of conditions and the following disclaimer in the documentation
	* and/or other materials provided with the distribution.
	* 3. The name of the author may not be used to endorse or promote products
	* derived from this software without specific prior written permission.
	*
	* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
	* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
	* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
	* EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
	* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
	* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
	* OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
	* WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
	* OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
	* ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
	*/

	package org.webrtc;

	import android.graphics.SurfaceTexture;
	import android.opengl.GLES11Ext;
	import android.opengl.GLES20;
	import android.os.Build;
	import android.os.Handler;
	import android.os.HandlerThread;
	import android.os.SystemClock;

	import java.nio.ByteBuffer;
	import java.nio.FloatBuffer;
	import java.util.concurrent.Callable;
	import java.util.concurrent.CountDownLatch;
	import java.util.concurrent.TimeUnit;

	/**
	* Helper class to create and synchronize access to a SurfaceTexture. The caller will get notified
	* of new frames in onTextureFrameAvailable(), and should call returnTextureFrame() when done with
	* the frame. Only one texture frame can be in flight at once, so returnTextureFrame() must be
	* called in order to receive a new frame. Call disconnect() to stop receiveing new frames and
	* release all resources.
	* Note that there is a C++ counter part of this class that optionally can be used. It is used for
	* wrapping texture frames into webrtc::VideoFrames and also handles calling returnTextureFrame()
	* when the webrtc::VideoFrame is no longer used.
	*/
	class SurfaceTextureHelper {
	private static final String TAG = "SurfaceTextureHelper";
	/**
	* Callback interface for being notified that a new texture frame is available. The calls will be
	* made on a dedicated thread with a bound EGLContext. The thread will be the same throughout the
	* lifetime of the SurfaceTextureHelper instance, but different from the thread calling the
	* SurfaceTextureHelper constructor. The callee is not allowed to make another EGLContext current
	* on the calling thread.
	*/
	public interface OnTextureFrameAvailableListener {
	abstract void onTextureFrameAvailable(
	int oesTextureId, float[] transformMatrix, long timestampNs);
	}

	public static SurfaceTextureHelper create(EglBase.Context sharedContext) {
	return create(sharedContext, null);
	}

	/**
	* Construct a new SurfaceTextureHelper sharing OpenGL resources with \|sharedContext\|. If
	* \|handler\| is non-null, the callback will be executed on that handler's thread. If \|handler\| is
	* null, a dedicated private thread is created for the callbacks.
	*/
	public static SurfaceTextureHelper create(final EglBase.Context sharedContext,
	final Handler handler) {
	final Handler finalHandler;
	if (handler != null) {
	finalHandler = handler;
	} else {
	final HandlerThread thread = new HandlerThread(TAG);
	thread.start();
	finalHandler = new Handler(thread.getLooper());
	}
	// The onFrameAvailable() callback will be executed on the SurfaceTexture ctor thread. See:
	// http://grepcode.com/file/repository.grepcode.com/java/ext/com.google.android/android/5.1.1_r1/android/graphics/SurfaceTexture.java#195.
	// Therefore, in order to control the callback thread on API lvl < 21, the SurfaceTextureHelper
	// is constructed on the \|handler\| thread.
	return ThreadUtils.invokeUninterruptibly(finalHandler, new Callable<SurfaceTextureHelper>() {
	@Override public SurfaceTextureHelper call() {
	return new SurfaceTextureHelper(sharedContext, finalHandler, (handler == null));
	}
	});
	}

	// State for YUV conversion, instantiated on demand.
	static private class YuvConverter {
	private final EglBase eglBase;
	private final GlShader shader;
	private boolean released = false;

	// Vertex coordinates in Normalized Device Coordinates, i.e.
	// (-1, -1) is bottom-left and (1, 1) is top-right.
	private static final FloatBuffer DEVICE_RECTANGLE =
	GlUtil.createFloatBuffer(new float[] {
	-1.0f, -1.0f, // Bottom left.
	1.0f, -1.0f, // Bottom right.
	-1.0f, 1.0f, // Top left.
	1.0f, 1.0f, // Top right.
	});

	// Texture coordinates - (0, 0) is bottom-left and (1, 1) is top-right.
	private static final FloatBuffer TEXTURE_RECTANGLE =
	GlUtil.createFloatBuffer(new float[] {
	0.0f, 0.0f, // Bottom left.
	1.0f, 0.0f, // Bottom right.
	0.0f, 1.0f, // Top left.
	1.0f, 1.0f // Top right.
	});

	private static final String VERTEX_SHADER =
	"varying vec2 interp_tc;\n"
	+ "attribute vec4 in_pos;\n"
	+ "attribute vec4 in_tc;\n"
	+ "\n"
	+ "uniform mat4 texMatrix;\n"
	+ "\n"
	+ "void main() {\n"
	+ " gl_Position = in_pos;\n"
	+ " interp_tc = (texMatrix * in_tc).xy;\n"
	+ "}\n";

	private static final String FRAGMENT_SHADER =
	"#extension GL_OES_EGL_image_external : require\n"
	+ "precision mediump float;\n"
	+ "varying vec2 interp_tc;\n"
	+ "\n"
	+ "uniform samplerExternalOES oesTex;\n"
	// Difference in texture coordinate corresponding to one
	// sub-pixel in the x direction.
	+ "uniform vec2 xUnit;\n"
	// Color conversion coefficients, including constant term
	+ "uniform vec4 coeffs;\n"
	+ "\n"
	+ "void main() {\n"
	// Since the alpha read from the texture is always 1, this could
	// be written as a mat4 x vec4 multiply. However, that seems to
	// give a worse framerate, possibly because the additional
	// multiplies by 1.0 consume resources. TODO(nisse): Could also
	// try to do it as a vec3 x mat3x4, followed by an add in of a
	// constant vector.
	+ " gl_FragColor.r = coeffs.a + dot(coeffs.rgb,\n"
	+ " texture2D(oesTex, interp_tc - 1.5 * xUnit).rgb);\n"
	+ " gl_FragColor.g = coeffs.a + dot(coeffs.rgb,\n"
	+ " texture2D(oesTex, interp_tc - 0.5 * xUnit).rgb);\n"
	+ " gl_FragColor.b = coeffs.a + dot(coeffs.rgb,\n"
	+ " texture2D(oesTex, interp_tc + 0.5 * xUnit).rgb);\n"
	+ " gl_FragColor.a = coeffs.a + dot(coeffs.rgb,\n"
	+ " texture2D(oesTex, interp_tc + 1.5 * xUnit).rgb);\n"
	+ "}\n";

	private int texMatrixLoc;
	private int xUnitLoc;
	private int coeffsLoc;;

	YuvConverter (EglBase.Context sharedContext) {
	eglBase = EglBase.create(sharedContext, EglBase.CONFIG_PIXEL_RGBA_BUFFER);
	eglBase.createDummyPbufferSurface();
	eglBase.makeCurrent();

	shader = new GlShader(VERTEX_SHADER, FRAGMENT_SHADER);
	shader.useProgram();
	texMatrixLoc = shader.getUniformLocation("texMatrix");
	xUnitLoc = shader.getUniformLocation("xUnit");
	coeffsLoc = shader.getUniformLocation("coeffs");
	GLES20.glUniform1i(shader.getUniformLocation("oesTex"), 0);
	GlUtil.checkNoGLES2Error("Initialize fragment shader uniform values.");
	// Initialize vertex shader attributes.
	shader.setVertexAttribArray("in_pos", 2, DEVICE_RECTANGLE);
	// If the width is not a multiple of 4 pixels, the texture
	// will be scaled up slightly and clipped at the right border.
	shader.setVertexAttribArray("in_tc", 2, TEXTURE_RECTANGLE);
	eglBase.detachCurrent();
	}

	synchronized void convert(ByteBuffer buf,
	int width, int height, int stride, int textureId, float [] transformMatrix) {
	if (released) {
	throw new IllegalStateException(
	"YuvConverter.convert called on released object");
	}

	// We draw into a buffer laid out like
	//
	// +---------+
	// \| \|
	// \| Y \|
	// \| \|
	// \| \|
	// +----+----+
	// \| U \| V \|
	// \| \| \|
	// +----+----+
	//
	// In memory, we use the same stride for all of Y, U and V. The
	// U data starts at offset \|height\| * \|stride\| from the Y data,
	// and the V data starts at at offset \|stride/2\| from the U
	// data, with rows of U and V data alternating.
	//
	// Now, it would have made sense to allocate a pixel buffer with
	// a single byte per pixel (EGL10.EGL_COLOR_BUFFER_TYPE,
	// EGL10.EGL_LUMINANCE_BUFFER,), but that seems to be
	// unsupported by devices. So do the following hack: Allocate an
	// RGBA buffer, of width \|stride\|/4. To render each of these
	// large pixels, sample the texture at 4 different x coordinates
	// and store the results in the four components.
	//
	// Since the V data needs to start on a boundary of such a
	// larger pixel, it is not sufficient that \|stride\| is even, it
	// has to be a multiple of 8 pixels.

	if (stride % 8 != 0) {
	throw new IllegalArgumentException(
	"Invalid stride, must be a multiple of 8");
	}
	if (stride < width){
	throw new IllegalArgumentException(
	"Invalid stride, must >= width");
	}

	int y_width = (width+3) / 4;
	int uv_width = (width+7) / 8;
	int uv_height = (height+1)/2;
	int total_height = height + uv_height;
	int size = stride * total_height;

	if (buf.capacity() < size) {
	throw new IllegalArgumentException("YuvConverter.convert called with too small buffer");
	}
	// Produce a frame buffer starting at top-left corner, not
	// bottom-left.
	transformMatrix =
	RendererCommon.multiplyMatrices(transformMatrix,
	RendererCommon.verticalFlipMatrix());

	// Create new pBuffferSurface with the correct size if needed.
	if (eglBase.hasSurface()) {
	if (eglBase.surfaceWidth() != stride/4 \|\|
	eglBase.surfaceHeight() != total_height){
	eglBase.releaseSurface();
	eglBase.createPbufferSurface(stride/4, total_height);
	}
	} else {
	eglBase.createPbufferSurface(stride/4, total_height);
	}

	eglBase.makeCurrent();

	GLES20.glActiveTexture(GLES20.GL_TEXTURE0);
	GLES20.glBindTexture(GLES11Ext.GL_TEXTURE_EXTERNAL_OES, textureId);
	GLES20.glUniformMatrix4fv(texMatrixLoc, 1, false, transformMatrix, 0);

	// Draw Y
	GLES20.glViewport(0, 0, y_width, height);
	// Matrix * (1;0;0;0) / width. Note that opengl uses column major order.
	GLES20.glUniform2f(xUnitLoc,
	transformMatrix[0] / width,
	transformMatrix[1] / width);
	// Y'UV444 to RGB888, see
	// https://en.wikipedia.org/wiki/YUV#Y.27UV444_to_RGB888_conversion.
	// We use the ITU-R coefficients for U and V */
	GLES20.glUniform4f(coeffsLoc, 0.299f, 0.587f, 0.114f, 0.0f);
	GLES20.glDrawArrays(GLES20.GL_TRIANGLE_STRIP, 0, 4);

	// Draw U
	GLES20.glViewport(0, height, uv_width, uv_height);
	// Matrix * (1;0;0;0) / (2*width). Note that opengl uses column major order.
	GLES20.glUniform2f(xUnitLoc,
	transformMatrix[0] / (2.0f*width),
	transformMatrix[1] / (2.0f*width));
	GLES20.glUniform4f(coeffsLoc, -0.169f, -0.331f, 0.499f, 0.5f);
	GLES20.glDrawArrays(GLES20.GL_TRIANGLE_STRIP, 0, 4);

	// Draw V
	GLES20.glViewport(stride/8, height, uv_width, uv_height);
	GLES20.glUniform4f(coeffsLoc, 0.499f, -0.418f, -0.0813f, 0.5f);
	GLES20.glDrawArrays(GLES20.GL_TRIANGLE_STRIP, 0, 4);

	GLES20.glReadPixels(0, 0, stride/4, total_height, GLES20.GL_RGBA,
	GLES20.GL_UNSIGNED_BYTE, buf);

	GlUtil.checkNoGLES2Error("YuvConverter.convert");

	// Unbind texture. Reportedly needed on some devices to get
	// the texture updated from the camera.
	GLES20.glBindTexture(GLES11Ext.GL_TEXTURE_EXTERNAL_OES, 0);
	eglBase.detachCurrent();
	}

	synchronized void release() {
	released = true;
	eglBase.makeCurrent();
	shader.release();
	eglBase.release();
	}
	}

	private final Handler handler;
	private boolean isOwningThread;
	private final EglBase eglBase;
	private final SurfaceTexture surfaceTexture;
	private final int oesTextureId;
	private YuvConverter yuvConverter;

	private OnTextureFrameAvailableListener listener;
	// The possible states of this class.
	private boolean hasPendingTexture = false;
	private boolean isTextureInUse = false;
	private boolean isQuitting = false;

	private SurfaceTextureHelper(EglBase.Context sharedContext,
	Handler handler, boolean isOwningThread) {
	if (handler.getLooper().getThread() != Thread.currentThread()) {
	throw new IllegalStateException("SurfaceTextureHelper must be created on the handler thread");
	}
	this.handler = handler;
	this.isOwningThread = isOwningThread;

	eglBase = EglBase.create(sharedContext, EglBase.CONFIG_PIXEL_BUFFER);
	eglBase.createDummyPbufferSurface();
	eglBase.makeCurrent();

	oesTextureId = GlUtil.generateTexture(GLES11Ext.GL_TEXTURE_EXTERNAL_OES);
	surfaceTexture = new SurfaceTexture(oesTextureId);
	}

	private YuvConverter getYuvConverter() {
	// yuvConverter is assigned once
	if (yuvConverter != null)
	return yuvConverter;

	synchronized(this) {
	if (yuvConverter == null)
	yuvConverter = new YuvConverter(eglBase.getEglBaseContext());
	return yuvConverter;
	}
	}

	/**
	* Start to stream textures to the given \|listener\|.
	* A Listener can only be set once.
	*/
	public void setListener(OnTextureFrameAvailableListener listener) {
	if (this.listener != null) {
	throw new IllegalStateException("SurfaceTextureHelper listener has already been set.");
	}
	this.listener = listener;
	surfaceTexture.setOnFrameAvailableListener(new SurfaceTexture.OnFrameAvailableListener() {
	@Override
	public void onFrameAvailable(SurfaceTexture surfaceTexture) {
	hasPendingTexture = true;
	tryDeliverTextureFrame();
	}
	});
	}

	/**
	* Retrieve the underlying SurfaceTexture. The SurfaceTexture should be passed in to a video
	* producer such as a camera or decoder.
	*/
	public SurfaceTexture getSurfaceTexture() {
	return surfaceTexture;
	}

	/**
	* Call this function to signal that you are done with the frame received in
	* onTextureFrameAvailable(). Only one texture frame can be in flight at once, so you must call
	* this function in order to receive a new frame.
	*/
	public void returnTextureFrame() {
	handler.post(new Runnable() {
	@Override public void run() {
	isTextureInUse = false;
	if (isQuitting) {
	release();
	} else {
	tryDeliverTextureFrame();
	}
	}
	});
	}

	/**
	* Call disconnect() to stop receiving frames. Resources are released when the texture frame has
	* been returned by a call to returnTextureFrame(). You are guaranteed to not receive any more
	* onTextureFrameAvailable() after this function returns.
	*/
	public void disconnect() {
	if (!isOwningThread) {
	throw new IllegalStateException("Must call disconnect(handler).");
	}
	if (handler.getLooper().getThread() == Thread.currentThread()) {
	isQuitting = true;
	if (!isTextureInUse) {
	release();
	}
	return;
	}
	final CountDownLatch barrier = new CountDownLatch(1);
	handler.postAtFrontOfQueue(new Runnable() {
	@Override public void run() {
	isQuitting = true;
	barrier.countDown();
	if (!isTextureInUse) {
	release();
	}
	}
	});
	ThreadUtils.awaitUninterruptibly(barrier);
	}

	/**
	* Call disconnect() to stop receiving frames and quit the looper used by \|handler\|.
	* Resources are released when the texture frame has been returned by a call to
	* returnTextureFrame(). You are guaranteed to not receive any more
	* onTextureFrameAvailable() after this function returns.
	*/
	public void disconnect(Handler handler) {
	if (this.handler != handler) {
	throw new IllegalStateException("Wrong handler.");
	}
	isOwningThread = true;
	disconnect();
	}

	public void textureToYUV(ByteBuffer buf,
	int width, int height, int stride, int textureId, float [] transformMatrix) {
	if (textureId != oesTextureId)
	throw new IllegalStateException("textureToByteBuffer called with unexpected textureId");

	getYuvConverter().convert(buf, width, height, stride, textureId, transformMatrix);
	}

	private void tryDeliverTextureFrame() {
	if (handler.getLooper().getThread() != Thread.currentThread()) {
	throw new IllegalStateException("Wrong thread.");
	}
	if (isQuitting \|\| !hasPendingTexture \|\| isTextureInUse) {
	return;
	}
	isTextureInUse = true;
	hasPendingTexture = false;

	eglBase.makeCurrent();
	surfaceTexture.updateTexImage();

	final float[] transformMatrix = new float[16];
	surfaceTexture.getTransformMatrix(transformMatrix);
	final long timestampNs = (Build.VERSION.SDK_INT >= Build.VERSION_CODES.ICE_CREAM_SANDWICH)
	? surfaceTexture.getTimestamp()
	: TimeUnit.MILLISECONDS.toNanos(SystemClock.elapsedRealtime());
	listener.onTextureFrameAvailable(oesTextureId, transformMatrix, timestampNs);
	}

	private void release() {
	if (handler.getLooper().getThread() != Thread.currentThread()) {
	throw new IllegalStateException("Wrong thread.");
	}
	if (isTextureInUse \|\| !isQuitting) {
	throw new IllegalStateException("Unexpected release.");
	}
	synchronized (this) {
	if (yuvConverter != null)
	yuvConverter.release();
	}
	eglBase.makeCurrent();
	GLES20.glDeleteTextures(1, new int[] {oesTextureId}, 0);
	surfaceTexture.release();
	eglBase.release();
	handler.getLooper().quit();
	}
	}