Extension to Gaussian Blur: support changing blur over time

PiperOrigin-RevId: 597809380

libraries/effect/src/androidTest/java/androidx/media3/effect/GaussianBlurTest.java

@@ -99,4 +99,28 @@ public class GaussianBlurTest {
     assertThat(actualPresentationTimesUs).containsExactly(32_000L);
     getAndAssertOutputBitmaps(textureBitmapReader, actualPresentationTimesUs, testId, ASSET_PATH);
   }
+
+  @Test
+  @RequiresNonNull({"textureBitmapReader", "testId"})
+  public void gaussianBlur_sigmaChangesWithTime_differentFramesHaveDifferentBlurs()
+      throws Exception {
+    ImmutableList<Long> frameTimesUs = ImmutableList.of(32_000L, 71_000L);
+    ImmutableList<Long> actualPresentationTimesUs =
+        generateAndProcessFrames(
+            BLANK_FRAME_WIDTH,
+            BLANK_FRAME_HEIGHT,
+            frameTimesUs,
+            new SeparableConvolution() {
+              @Override
+              public ConvolutionFunction1D getConvolution(long presentationTimeUs) {
+                return new GaussianFunction(
+                    presentationTimeUs < 40_000L ? 5f : 20f, /* numStandardDeviations= */ 2.0f);
+              }
+            },
+            textureBitmapReader,
+            TEXT_SPAN_CONSUMER);
+
+    assertThat(actualPresentationTimesUs).containsExactly(32_000L, 71_000L);
+    getAndAssertOutputBitmaps(textureBitmapReader, actualPresentationTimesUs, testId, ASSET_PATH);
+  }
 }

libraries/effect/src/main/java/androidx/media3/effect/GaussianBlur.java

@@ -51,11 +51,10 @@ public final class GaussianBlur extends SeparableConvolution {
    */
   public GaussianBlur(float sigma) {
     this(sigma, /* numStandardDeviations= */ 2.0f);
-    ;
   }
 
   @Override
-  public ConvolutionFunction1D getConvolution() {
+  public ConvolutionFunction1D getConvolution(long presentationTimeUs) {
     return new GaussianFunction(sigma, numStandardDeviations);
   }
 }

libraries/effect/src/main/java/androidx/media3/effect/GaussianFunction.java

@@ -21,7 +21,9 @@ import static java.lang.Math.exp;
 import static java.lang.Math.sqrt;
 
 import androidx.annotation.FloatRange;
+import androidx.annotation.Nullable;
 import androidx.media3.common.util.UnstableApi;
+import java.util.Objects;
 
 /**
  * Implementation of a symmetric Gaussian function with a limited domain.
@@ -68,4 +70,21 @@ public final class GaussianFunction implements ConvolutionFunction1D {
     return (float)
         (exp(-samplePositionOverSigma * samplePositionOverSigma / 2) / sqrt(2 * PI) / sigma);
   }
+
+  @Override
+  public boolean equals(@Nullable Object o) {
+    if (this == o) {
+      return true;
+    }
+    if (!(o instanceof GaussianFunction)) {
+      return false;
+    }
+    GaussianFunction that = (GaussianFunction) o;
+    return Float.compare(that.sigma, sigma) == 0 && Float.compare(that.numStdDev, numStdDev) == 0;
+  }
+
+  @Override
+  public int hashCode() {
+    return Objects.hash(sigma, numStdDev);
+  }
 }

libraries/effect/src/main/java/androidx/media3/effect/SeparableConvolution.java

@@ -46,8 +46,12 @@ public abstract class SeparableConvolution implements GlEffect {
     this.scaleFactor = scaleFactor;
   }
 
-  /** Returns a {@linkplain ConvolutionFunction1D 1D convolution function}. */
-  public abstract ConvolutionFunction1D getConvolution();
+  /**
+   * Returns a {@linkplain ConvolutionFunction1D 1D convolution function}.
+   *
+   * @param presentationTimeUs The presentation timestamp of the input frame, in microseconds.
+   */
+  public abstract ConvolutionFunction1D getConvolution(long presentationTimeUs);
 
   @Override
   public GlShaderProgram toGlShaderProgram(Context context, boolean useHdr)

libraries/effect/src/main/java/androidx/media3/effect/SeparableConvolutionShaderProgram.java

@@ -34,6 +34,7 @@ import com.google.common.util.concurrent.MoreExecutors;
 import java.io.IOException;
 import java.nio.ShortBuffer;
 import java.util.concurrent.Executor;
+import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
 
 /**
  * A {@link GlShaderProgram} for performing separable convolutions.
@@ -87,6 +88,7 @@ import java.util.concurrent.Executor;
   private float functionLutCenterX;
   private float functionLutDomainStart;
   private float functionLutWidth;
+  private @MonotonicNonNull ConvolutionFunction1D lastConvolutionFunction;
 
   /**
    * Creates an instance.
@@ -108,11 +110,12 @@ import java.util.concurrent.Executor;
     inputListener = new InputListener() {};
     outputListener = new OutputListener() {};
     errorListener = (frameProcessingException) -> {};
-
     errorListenerExecutor = MoreExecutors.directExecutor();
     lastInputSize = Size.ZERO;
     intermediateSize = Size.ZERO;
     outputSize = Size.ZERO;
+    lastConvolutionFunction = null;
+
     try {
       glProgram = new GlProgram(context, VERTEX_SHADER_PATH, FRAGMENT_SHADER_PATH);
       sharpTransformGlProgram =
@@ -160,7 +163,7 @@ import java.util.concurrent.Executor;
             + " first.");
     try {
       ensureTexturesAreConfigured(
-          glObjectsProvider, new Size(inputTexture.width, inputTexture.height));
+          glObjectsProvider, new Size(inputTexture.width, inputTexture.height), presentationTimeUs);
       outputTextureInUse = true;
       renderHorizontal(inputTexture);
       renderVertical();
@@ -269,10 +272,15 @@ import java.util.concurrent.Executor;
     renderOnePass(intermediateTexture.texId, /* isHorizontal= */ false);
   }
 
-  private void ensureTexturesAreConfigured(GlObjectsProvider glObjectsProvider, Size inputSize)
+  private void ensureTexturesAreConfigured(
+      GlObjectsProvider glObjectsProvider, Size inputSize, long presentationTimeUs)
       throws GlUtil.GlException {
-    // Always update the function texture, as it could change on each render cycle.
-    updateFunctionTexture(glObjectsProvider);
+    ConvolutionFunction1D currentConvolutionFunction =
+        convolution.getConvolution(presentationTimeUs);
+    if (!currentConvolutionFunction.equals(lastConvolutionFunction)) {
+      updateFunctionTexture(glObjectsProvider, currentConvolutionFunction);
+      lastConvolutionFunction = currentConvolutionFunction;
+    }
 
     // Only update intermediate and output textures if the size changes.
     if (inputSize.equals(lastInputSize)) {
@@ -295,11 +303,10 @@ import java.util.concurrent.Executor;
    * Creates a function lookup table for the convolution, and stores it in a 16b floating point
    * texture for GPU access.
    */
-  private void updateFunctionTexture(GlObjectsProvider glObjectsProvider)
+  private void updateFunctionTexture(
+      GlObjectsProvider glObjectsProvider, ConvolutionFunction1D convolutionFunction)
       throws GlUtil.GlException {
 
-    ConvolutionFunction1D convolutionFunction = convolution.getConvolution();
-
     int lutRasterSize =
         (int)
             Math.ceil(