Effect: Clarify that padding is added in ScaleToFitTransformation.

PiperOrigin-RevId: 504796380

library/effect/src/main/java/com/google/android/exoplayer2/effect/GlMatrixTransformation.java

@@ -22,7 +22,7 @@ import com.google.android.exoplayer2.util.Size;
 import com.google.common.collect.ImmutableList;
 
 /**
- * Specifies a 4x4 transformation {@link Matrix} to apply in the vertex shader for each frame.
+ * Specifies a 4x4 transformation {@link Matrix} to apply in the vertex shader for each input frame.
  *
  * <p>The matrix is applied to points given in normalized device coordinates (-1 to 1 on x, y, and z
  * axes). Transformed pixels that are moved outside of the normal device coordinate range are

library/effect/src/main/java/com/google/android/exoplayer2/effect/ScaleToFitTransformation.java

@@ -72,9 +72,9 @@ public final class ScaleToFitTransformation implements MatrixTransformation {
      *
      * <p>The default value, 0, corresponds to not applying any rotation.
      *
-     * <p>The output frame's width and height are automatically adjusted to preserve all input
-     * pixels. The rotated input frame is fitted inside an enclosing black rectangle if its edges
-     * aren't parallel to the x and y axes.
+     * <p>The output frame's width and height are adjusted to preserve all input pixels. The rotated
+     * input frame is fitted inside an enclosing black rectangle if its edges aren't parallel to the
+     * x and y axes, to form the output frame.
      *
      * @param rotationDegrees The counterclockwise rotation, in degrees.
      * @return This builder.