Android: Move YuvConverter to its own file

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

+/*
+ *  Copyright 2015 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.opengl.GLES11Ext;
+import android.opengl.GLES20;
+import java.nio.ByteBuffer;
+import java.nio.FloatBuffer;
+
+/**
+ * Class for converting OES textures to a YUV ByteBuffer.
+ */
+public class YuvConverter {

[sakal, 2016/10/19 11:16:02]

nit: Do we want to expose this class to external users?

[magjed_webrtc, 2016/10/19 12:27:01]

Ok, let's make it package private for now.

+  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.
+  });
+
+  // clang-format off
+  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";
+  // clang-format on
+
+  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) / (width / 2). Note that opengl uses column major order.
+    GLES20.glUniform2f(
+        xUnitLoc, 2.0f * transformMatrix[0] / width, 2.0f * transformMatrix[1] / 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();
+  }
+}