From 337e59e733ffa6bdc5b9badbcff6d143ceb3e4e6 Mon Sep 17 00:00:00 2001
From: ivanbuper <ivanbuper@google.com>
Date: Fri, 11 Oct 2024 07:58:46 -0700
Subject: [PATCH] Move util methods in `SpeedChangingAudioProcessor`to `Util`

This CL is prework for implementing
`RandomParameterizedSpeedChangingAudioProcessorTest`, which will build
on logic present in `RandomParameterizedSonicTest`.

This is a non-functional change.

PiperOrigin-RevId: 684838017
---
 .../audio/RandomParameterizedSonicTest.java   | 17 ++++-----
 .../androidx/media3/test/utils/TestUtil.java  | 35 +++++++++++++++++++
 2 files changed, 41 insertions(+), 11 deletions(-)

diff --git a/libraries/common/src/test/java/androidx/media3/common/audio/RandomParameterizedSonicTest.java b/libraries/common/src/test/java/androidx/media3/common/audio/RandomParameterizedSonicTest.java
index cb474f2d50..515d4b5783 100644
--- a/libraries/common/src/test/java/androidx/media3/common/audio/RandomParameterizedSonicTest.java
+++ b/libraries/common/src/test/java/androidx/media3/common/audio/RandomParameterizedSonicTest.java
@@ -15,6 +15,8 @@
  */
 package androidx.media3.common.audio;
 
+import static androidx.media3.test.utils.TestUtil.generateFloatInRange;
+import static androidx.media3.test.utils.TestUtil.roundToDecimalPlaces;
 import static com.google.common.truth.Truth.assertThat;
 import static java.lang.Math.max;
 
@@ -97,8 +99,10 @@ public final class RandomParameterizedSonicTest {
     ImmutableSet.Builder<Float> speedsBuilder = new ImmutableSet.Builder<>();
 
     for (int i = 0; i < PARAM_COUNT; i++) {
-      Range<Float> r = SPEED_RANGES.get(i % SPEED_RANGES.size());
-      speedsBuilder.add(round(generateFloatInRange(r)));
+      Range<Float> range = SPEED_RANGES.get(i % SPEED_RANGES.size());
+      speedsBuilder.add(
+          (float)
+              roundToDecimalPlaces(generateFloatInRange(random, range), SPEED_DECIMAL_PRECISION));
     }
     ImmutableSet<Float> speeds = speedsBuilder.build();
 
@@ -235,13 +239,4 @@ public final class RandomParameterizedSonicTest {
 
     assertThat(readSampleCount).isWithin(tolerance).of(expectedSampleCount.longValueExact());
   }
-
-  private static float round(float num) {
-    BigDecimal bigDecimal = new BigDecimal(Float.toString(num));
-    return bigDecimal.setScale(SPEED_DECIMAL_PRECISION, RoundingMode.HALF_EVEN).floatValue();
-  }
-
-  private static float generateFloatInRange(Range<Float> r) {
-    return r.lowerEndpoint() + random.nextFloat() * (r.upperEndpoint() - r.lowerEndpoint());
-  }
 }
diff --git a/libraries/test_utils/src/main/java/androidx/media3/test/utils/TestUtil.java b/libraries/test_utils/src/main/java/androidx/media3/test/utils/TestUtil.java
index 6552b2d411..b3b6f2fe77 100644
--- a/libraries/test_utils/src/main/java/androidx/media3/test/utils/TestUtil.java
+++ b/libraries/test_utils/src/main/java/androidx/media3/test/utils/TestUtil.java
@@ -51,7 +51,9 @@ import androidx.media3.extractor.ExtractorInput;
 import androidx.media3.extractor.PositionHolder;
 import androidx.media3.extractor.SeekMap;
 import androidx.media3.extractor.metadata.MetadataInputBuffer;
+import com.google.common.collect.BoundType;
 import com.google.common.collect.ImmutableList;
+import com.google.common.collect.Range;
 import com.google.common.io.ByteStreams;
 import com.google.common.primitives.Bytes;
 import com.google.common.primitives.UnsignedBytes;
@@ -63,6 +65,8 @@ import java.io.IOException;
 import java.io.InputStream;
 import java.lang.reflect.Method;
 import java.lang.reflect.Modifier;
+import java.math.BigDecimal;
+import java.math.RoundingMode;
 import java.nio.ByteBuffer;
 import java.nio.ByteOrder;
 import java.nio.FloatBuffer;
@@ -663,6 +667,37 @@ public class TestUtil {
     return checkNotNull(parcel.readBundle(throwingClassLoader));
   }
 
+  /**
+   * Returns a randomly generated float within the specified range, using {@code random} as random
+   * number generator.
+   *
+   * <p>{@code range} must be a bounded range.
+   */
+  public static float generateFloatInRange(Random random, Range<Float> range) {
+    float bottom =
+        range.lowerBoundType() == BoundType.OPEN
+            ? Math.nextUp(range.lowerEndpoint())
+            : range.lowerEndpoint();
+    float top =
+        range.upperBoundType() == BoundType.OPEN
+            ? Math.nextDown(range.upperEndpoint())
+            : range.upperEndpoint();
+
+    return bottom + random.nextFloat() * (top - bottom);
+  }
+
+  /**
+   * Rounds {@code num} to {@code decimalPlaces}, using {@link RoundingMode#HALF_EVEN}.
+   *
+   * <p>The number is converted first into a {@link BigDecimal} on which the scale is set to {@code
+   * decimalPlaces}. Finally, the method returns the {@link BigDecimal#doubleValue()} of the scaled
+   * big decimal.
+   */
+  public static double roundToDecimalPlaces(double num, int decimalPlaces) {
+    BigDecimal bigDecimal = new BigDecimal(Double.toString(num));
+    return bigDecimal.setScale(decimalPlaces, RoundingMode.HALF_EVEN).doubleValue();
+  }
+
   private static final class NoUidOrShufflingTimeline extends Timeline {
 
     private final Timeline delegate;