Implement RGBA color matrices processor

* Transform frame colors using a defined RGBA Matrix to apply filters.

PiperOrigin-RevId: 464523581
(cherry picked from commit 23f34f8d)

library/transformer/src/androidTest/java/com/google/android/exoplayer2/transformer/RgbaMatrixPixelTest.java

+/*
+ * Copyright 2022 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.android.exoplayer2.transformer;
+
+import static androidx.test.core.app.ApplicationProvider.getApplicationContext;
+import static com.google.android.exoplayer2.transformer.BitmapTestUtil.MAXIMUM_AVERAGE_PIXEL_ABSOLUTE_DIFFERENCE;
+import static com.google.android.exoplayer2.util.Assertions.checkNotNull;
+import static com.google.common.truth.Truth.assertThat;
+
+import android.content.Context;
+import android.graphics.Bitmap;
+import android.graphics.Color;
+import android.opengl.EGLContext;
+import android.opengl.EGLDisplay;
+import android.opengl.EGLSurface;
+import android.opengl.Matrix;
+import android.util.Pair;
+import androidx.media3.common.FrameProcessingException;
+import androidx.test.ext.junit.runners.AndroidJUnit4;
+import com.google.android.exoplayer2.util.GlUtil;
+import java.io.IOException;
+import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
+/**
+ * Pixel tests for {@link RgbaMatrix}.
+ *
+ * <p>Expected images are taken from an emulator, so tests on different emulators or physical
+ * devices may fail. To test on other devices, please increase the {@link
+ * BitmapTestUtil#MAXIMUM_AVERAGE_PIXEL_ABSOLUTE_DIFFERENCE} and/or inspect the saved output bitmaps
+ * as recommended in {@link GlEffectsFrameProcessorPixelTest}.
+ */
+@RunWith(AndroidJUnit4.class)
+public final class RgbaMatrixPixelTest {
+  public static final String ORIGINAL_PNG_ASSET_PATH =
+      "media/bitmap/sample_mp4_first_frame/original.png";
+  public static final String ONLY_RED_CHANNEL_PNG_ASSET_PATH =
+      "media/bitmap/sample_mp4_first_frame/only_red_channel.png";
+  public static final String INCREASE_BRIGHTNESS_PNG_ASSET_PATH =
+      "media/bitmap/sample_mp4_first_frame/increase_brightness.png";
+  public static final String GRAYSCALE_PNG_ASSET_PATH =
+      "media/bitmap/sample_mp4_first_frame/grayscale.png";
+  public static final int COLOR_MATRIX_RED_INDEX = 0;
+  public static final int COLOR_MATRIX_GREEN_INDEX = 5;
+  public static final int COLOR_MATRIX_BLUE_INDEX = 10;
+  public static final int COLOR_MATRIX_ALPHA_INDEX = 15;
+
+  private final Context context = getApplicationContext();
+
+  private @MonotonicNonNull EGLDisplay eglDisplay;
+  private @MonotonicNonNull EGLContext eglContext;
+  private @MonotonicNonNull SingleFrameGlTextureProcessor rgbaMatrixProcessor;
+  private @MonotonicNonNull EGLSurface placeholderEglSurface;
+  private int inputTexId;
+  private int outputTexId;
+  private int inputWidth;
+  private int inputHeight;
+
+  @Before
+  public void createGlObjects() throws IOException, GlUtil.GlException {
+    eglDisplay = GlUtil.createEglDisplay();
+    eglContext = GlUtil.createEglContext(eglDisplay);
+    Bitmap inputBitmap = BitmapTestUtil.readBitmap(ORIGINAL_PNG_ASSET_PATH);
+    inputWidth = inputBitmap.getWidth();
+    inputHeight = inputBitmap.getHeight();
+    placeholderEglSurface = GlUtil.createPlaceholderEglSurface(eglDisplay);
+    GlUtil.focusEglSurface(eglDisplay, eglContext, placeholderEglSurface, inputWidth, inputHeight);
+    inputTexId = BitmapTestUtil.createGlTextureFromBitmap(inputBitmap);
+
+    outputTexId =
+        GlUtil.createTexture(inputWidth, inputHeight, /* useHighPrecisionColorComponents= */ false);
+    int frameBuffer = GlUtil.createFboForTexture(outputTexId);
+    GlUtil.focusFramebuffer(
+        checkNotNull(eglDisplay),
+        checkNotNull(eglContext),
+        checkNotNull(placeholderEglSurface),
+        frameBuffer,
+        inputWidth,
+        inputHeight);
+  }
+
+  @After
+  public void release() throws GlUtil.GlException, FrameProcessingException {
+    if (rgbaMatrixProcessor != null) {
+      rgbaMatrixProcessor.release();
+    }
+    GlUtil.destroyEglContext(eglDisplay, eglContext);
+  }
+
+  private static RgbaMatrixProcessor createRgbaMatrixProcessor(Context context, float[] rgbaMatrix)
+      throws FrameProcessingException {
+    return ((RgbaMatrix) presentationTimeUs -> rgbaMatrix)
+        .toGlTextureProcessor(context, /* useHdr= */ false);
+  }
+
+  @Test
+  public void drawFrame_identityMatrix_leavesFrameUnchanged() throws Exception {
+    String testId = "drawFrame_identityMatrix";
+    float[] identityMatrix = new float[16];
+    Matrix.setIdentityM(identityMatrix, /* smOffset= */ 0);
+    rgbaMatrixProcessor = createRgbaMatrixProcessor(context, identityMatrix);
+    Pair<Integer, Integer> outputSize = rgbaMatrixProcessor.configure(inputWidth, inputHeight);
+    Bitmap expectedBitmap = BitmapTestUtil.readBitmap(ORIGINAL_PNG_ASSET_PATH);
+
+    rgbaMatrixProcessor.drawFrame(inputTexId, /* presentationTimeUs= */ 0);
+    Bitmap actualBitmap =
+        BitmapTestUtil.createArgb8888BitmapFromCurrentGlFramebuffer(
+            outputSize.first, outputSize.second);
+
+    BitmapTestUtil.maybeSaveTestBitmapToCacheDirectory(
+        testId, /* bitmapLabel= */ "actual", actualBitmap);
+    float averagePixelAbsoluteDifference =
+        BitmapTestUtil.getAveragePixelAbsoluteDifferenceArgb8888(
+            expectedBitmap, actualBitmap, testId);
+    assertThat(averagePixelAbsoluteDifference).isAtMost(MAXIMUM_AVERAGE_PIXEL_ABSOLUTE_DIFFERENCE);
+  }
+
+  @Test
+  public void drawFrame_removeColors_producesBlackFrame() throws Exception {
+    String testId = "drawFrame_removeColors";
+    float[] removeColorFilter = new float[16];
+    Matrix.setIdentityM(removeColorFilter, /* smOffset= */ 0);
+    removeColorFilter[COLOR_MATRIX_RED_INDEX] = 0;
+    removeColorFilter[COLOR_MATRIX_GREEN_INDEX] = 0;
+    removeColorFilter[COLOR_MATRIX_BLUE_INDEX] = 0;
+    rgbaMatrixProcessor = createRgbaMatrixProcessor(context, removeColorFilter);
+    Pair<Integer, Integer> outputSize = rgbaMatrixProcessor.configure(inputWidth, inputHeight);
+    Bitmap expectedBitmap =
+        BitmapTestUtil.createArgb8888BitmapWithSolidColor(
+            outputSize.first, outputSize.second, Color.BLACK);
+
+    rgbaMatrixProcessor.drawFrame(inputTexId, /* presentationTimeUs= */ 0);
+    Bitmap actualBitmap =
+        BitmapTestUtil.createArgb8888BitmapFromCurrentGlFramebuffer(
+            outputSize.first, outputSize.second);
+
+    BitmapTestUtil.maybeSaveTestBitmapToCacheDirectory(
+        testId, /* bitmapLabel= */ "actual", actualBitmap);
+    float averagePixelAbsoluteDifference =
+        BitmapTestUtil.getAveragePixelAbsoluteDifferenceArgb8888(
+            expectedBitmap, actualBitmap, testId);
+    assertThat(averagePixelAbsoluteDifference).isAtMost(MAXIMUM_AVERAGE_PIXEL_ABSOLUTE_DIFFERENCE);
+  }
+
+  @Test
+  public void drawFrame_redOnlyFilter_setsBlueAndGreenValuesToZero() throws Exception {
+    String testId = "drawFrame_redOnlyFilter";
+    float[] redOnlyFilter = new float[16];
+    Matrix.setIdentityM(redOnlyFilter, /* smOffset= */ 0);
+    redOnlyFilter[COLOR_MATRIX_GREEN_INDEX] = 0;
+    redOnlyFilter[COLOR_MATRIX_BLUE_INDEX] = 0;
+    rgbaMatrixProcessor = createRgbaMatrixProcessor(context, redOnlyFilter);
+    Pair<Integer, Integer> outputSize = rgbaMatrixProcessor.configure(inputWidth, inputHeight);
+    Bitmap expectedBitmap = BitmapTestUtil.readBitmap(ONLY_RED_CHANNEL_PNG_ASSET_PATH);
+
+    rgbaMatrixProcessor.drawFrame(inputTexId, /* presentationTimeUs= */ 0);
+    Bitmap actualBitmap =
+        BitmapTestUtil.createArgb8888BitmapFromCurrentGlFramebuffer(
+            outputSize.first, outputSize.second);
+
+    BitmapTestUtil.maybeSaveTestBitmapToCacheDirectory(
+        testId, /* bitmapLabel= */ "actual", actualBitmap);
+    float averagePixelAbsoluteDifference =
+        BitmapTestUtil.getAveragePixelAbsoluteDifferenceArgb8888(
+            expectedBitmap, actualBitmap, testId);
+    assertThat(averagePixelAbsoluteDifference).isAtMost(MAXIMUM_AVERAGE_PIXEL_ABSOLUTE_DIFFERENCE);
+  }
+
+  @Test
+  public void drawFrame_increaseBrightness_increasesAllValues() throws Exception {
+    String testId = "drawFrame_increaseBrightness";
+    float[] increaseBrightnessMatrix = new float[16];
+    Matrix.setIdentityM(increaseBrightnessMatrix, /* smOffset= */ 0);
+    Matrix.scaleM(increaseBrightnessMatrix, /* mOffset= */ 0, /* x= */ 5, /* y= */ 5, /* z= */ 5);
+    rgbaMatrixProcessor = createRgbaMatrixProcessor(context, increaseBrightnessMatrix);
+    Pair<Integer, Integer> outputSize = rgbaMatrixProcessor.configure(inputWidth, inputHeight);
+    Bitmap expectedBitmap = BitmapTestUtil.readBitmap(INCREASE_BRIGHTNESS_PNG_ASSET_PATH);
+
+    rgbaMatrixProcessor.drawFrame(inputTexId, /* presentationTimeUs= */ 0);
+    Bitmap actualBitmap =
+        BitmapTestUtil.createArgb8888BitmapFromCurrentGlFramebuffer(
+            outputSize.first, outputSize.second);
+
+    BitmapTestUtil.maybeSaveTestBitmapToCacheDirectory(
+        testId, /* bitmapLabel= */ "actual", actualBitmap);
+    float averagePixelAbsoluteDifference =
+        BitmapTestUtil.getAveragePixelAbsoluteDifferenceArgb8888(
+            expectedBitmap, actualBitmap, testId);
+    assertThat(averagePixelAbsoluteDifference).isAtMost(MAXIMUM_AVERAGE_PIXEL_ABSOLUTE_DIFFERENCE);
+  }
+
+  @Test
+  public void drawFrame_grayscale_producesGrayscaleImage() throws Exception {
+    String testId = "drawFrame_grayscale";
+    // Grayscale transformation matrix with the BT.709 standard from
+    // https://en.wikipedia.org/wiki/Grayscale#Converting_colour_to_grayscale
+    float[] grayscaleFilter = {
+      0.2126f, 0.2126f, 0.2126f, 0, 0.7152f, 0.7152f, 0.7152f, 0, 0.0722f, 0.0722f, 0.0722f, 0, 0,
+      0, 0, 1
+    };
+    rgbaMatrixProcessor = createRgbaMatrixProcessor(context, grayscaleFilter);
+    Pair<Integer, Integer> outputSize = rgbaMatrixProcessor.configure(inputWidth, inputHeight);
+    Bitmap expectedBitmap = BitmapTestUtil.readBitmap(GRAYSCALE_PNG_ASSET_PATH);
+
+    rgbaMatrixProcessor.drawFrame(inputTexId, /* presentationTimeUs= */ 0);
+    Bitmap actualBitmap =
+        BitmapTestUtil.createArgb8888BitmapFromCurrentGlFramebuffer(
+            outputSize.first, outputSize.second);
+
+    BitmapTestUtil.maybeSaveTestBitmapToCacheDirectory(
+        testId, /* bitmapLabel= */ "actual", actualBitmap);
+    float averagePixelAbsoluteDifference =
+        BitmapTestUtil.getAveragePixelAbsoluteDifferenceArgb8888(
+            expectedBitmap, actualBitmap, testId);
+    assertThat(averagePixelAbsoluteDifference).isAtMost(MAXIMUM_AVERAGE_PIXEL_ABSOLUTE_DIFFERENCE);
+  }
+}

library/transformer/src/main/assets/shaders/fragment_shader_transformation_es2.glsl

+#version 100
+// Copyright 2022 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// ES 2 fragment shader that samples from a (non-external) texture with
+// uTexSampler, copying from this texture to the current output while
+// applying a 4x4 RGBA color matrix to change the pixel colors.
+
+precision mediump float;
+uniform sampler2D uTexSampler;
+uniform mat4 uColorMatrix;
+varying vec2 vTexSamplingCoord;
+
+void main() {
+    vec4 inputColor = texture2D(uTexSampler, vTexSamplingCoord);
+    gl_FragColor = uColorMatrix * inputColor;
+}

library/transformer/src/main/java/com/google/android/exoplayer2/transformer/RgbaMatrix.java

+/*
+ * Copyright 2022 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.android.exoplayer2.transformer;
+
+import android.content.Context;
+import androidx.media3.common.FrameProcessingException;
+
+/**
+ * Specifies a 4x4 RGBA color transformation matrix to apply to each frame in the fragment shader.
+ */
+public interface RgbaMatrix extends GlEffect {
+
+  /**
+   * Returns the 4x4 RGBA transformation {@linkplain android.opengl.Matrix matrix} to apply to the
+   * color values of each pixel in the frame with the given timestamp.
+   */
+  float[] getMatrix(long presentationTimeUs);
+
+  @Override
+  default RgbaMatrixProcessor toGlTextureProcessor(Context context, boolean useHdr)
+      throws FrameProcessingException {
+    return new RgbaMatrixProcessor(context, /* rgbaMatrix= */ this, useHdr);
+  }
+}

library/transformer/src/main/java/com/google/android/exoplayer2/transformer/RgbaMatrixProcessor.java

+/*
+ * Copyright 2022 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.android.exoplayer2.transformer;
+
+import android.content.Context;
+import android.opengl.GLES20;
+import android.opengl.Matrix;
+import android.util.Pair;
+import androidx.media3.common.FrameProcessingException;
+import com.google.android.exoplayer2.util.GlProgram;
+import com.google.android.exoplayer2.util.GlUtil;
+import java.io.IOException;
+
+/** Applies an {@link RgbaMatrix} to each frame. */
+/* package */ final class RgbaMatrixProcessor extends SingleFrameGlTextureProcessor {
+  private static final String VERTEX_SHADER_PATH = "shaders/vertex_shader_transformation_es2.glsl";
+  private static final String FRAGMENT_SHADER_PATH =
+      "shaders/fragment_shader_transformation_es2.glsl";
+
+  private final GlProgram glProgram;
+  private final RgbaMatrix rgbaMatrix;
+
+  // TODO(b/239431666): Support chaining multiple RgbaMatrix instances in RgbaMatrixProcessor.
+  // TODO(b/239757183): Merge RgbaMatrixProcessor with MatrixTransformationProcessor.
+  public RgbaMatrixProcessor(Context context, RgbaMatrix rgbaMatrix, boolean useHdr)
+      throws FrameProcessingException {
+    super(useHdr);
+    this.rgbaMatrix = rgbaMatrix;
+
+    try {
+      glProgram = new GlProgram(context, VERTEX_SHADER_PATH, FRAGMENT_SHADER_PATH);
+    } catch (IOException | GlUtil.GlException e) {
+      throw new FrameProcessingException(e);
+    }
+
+    // Draw the frame on the entire normalized device coordinate space, from -1 to 1, for x and y.
+    glProgram.setBufferAttribute(
+        "aFramePosition",
+        GlUtil.getNormalizedCoordinateBounds(),
+        GlUtil.HOMOGENEOUS_COORDINATE_VECTOR_SIZE);
+
+    float[] identityMatrix = new float[16];
+    Matrix.setIdentityM(identityMatrix, /* smOffset= */ 0);
+    glProgram.setFloatsUniform("uTransformationMatrix", identityMatrix);
+    glProgram.setFloatsUniform("uTexTransformationMatrix", identityMatrix);
+  }
+
+  @Override
+  public Pair<Integer, Integer> configure(int inputWidth, int inputHeight) {
+    return Pair.create(inputWidth, inputHeight);
+  }
+
+  @Override
+  public void drawFrame(int inputTexId, long presentationTimeUs) throws FrameProcessingException {
+    float[] rgbaMatrixArray = rgbaMatrix.getMatrix(presentationTimeUs);
+    try {
+      glProgram.use();
+      glProgram.setSamplerTexIdUniform("uTexSampler", inputTexId, /* texUnitIndex= */ 0);
+      glProgram.setFloatsUniform("uColorMatrix", rgbaMatrixArray);
+      glProgram.bindAttributesAndUniforms();
+
+      // The four-vertex triangle strip forms a quad.
+      GLES20.glDrawArrays(GLES20.GL_TRIANGLE_STRIP, /* first= */ 0, /* count= */ 4);
+    } catch (GlUtil.GlException e) {
+      throw new FrameProcessingException(e, presentationTimeUs);
+    }
+  }
+}