/*
* 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. It should be constructed on a thread with
* an active EGL context, and only be used from that thread.
*/
class YuvConverter {
// 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 final GlTextureFrameBuffer textureFrameBuffer;
private final GlShader shader;
private final int texMatrixLoc;
private final int xUnitLoc;
private final int coeffsLoc;
private final ThreadUtils.ThreadChecker threadChecker = new ThreadUtils.ThreadChecker();
private boolean released = false;
/**
* This class should be constructed on a thread that has an active EGL context.
*/
public YuvConverter() {
threadChecker.checkIsOnValidThread();
textureFrameBuffer = new GlTextureFrameBuffer(GLES20.GL_RGBA);
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);
}
public void convert(ByteBuffer buf, int width, int height, int stride, int srcTextureId,
float[] transformMatrix) {
threadChecker.checkIsOnValidThread();
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());
final int frameBufferWidth = stride / 4;
final int frameBufferHeight = total_height;
textureFrameBuffer.setSize(frameBufferWidth, frameBufferHeight);
// Bind our framebuffer.
GLES20.glBindFramebuffer(GLES20.GL_FRAMEBUFFER, textureFrameBuffer.getFrameBufferId());
GlUtil.checkNoGLES2Error("glBindFramebuffer");
GLES20.glActiveTexture(GLES20.GL_TEXTURE0);
GLES20.glBindTexture(GLES11Ext.GL_TEXTURE_EXTERNAL_OES, srcTextureId);
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, frameBufferWidth, frameBufferHeight, GLES20.GL_RGBA, GLES20.GL_UNSIGNED_BYTE, buf);
GlUtil.checkNoGLES2Error("YuvConverter.convert");
// Restore normal framebuffer.
GLES20.glBindFramebuffer(GLES20.GL_FRAMEBUFFER, 0);
GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, 0);
// Unbind texture. Reportedly needed on some devices to get
// the texture updated from the camera.
GLES20.glBindTexture(GLES11Ext.GL_TEXTURE_EXTERNAL_OES, 0);
}
public void release() {
threadChecker.checkIsOnValidThread();
released = true;
shader.release();
textureFrameBuffer.release();
}
}
