Match the suggested bitrate to the actual Kush Gauge formula.

As defined in Kush Amerasinghe's paper 'H.264 For the rest of us'.

PiperOrigin-RevId: 446988272

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

@@ -502,11 +502,24 @@ public final class DefaultEncoderFactory implements Codec.EncoderFactory {
         && allowedMimeTypes.contains(mimeType);
   }
 
-  /** Computes the video bit rate using the Kush Gauge. */
+  /**
+   * Computes the video bit rate using the Kush Gauge.
+   *
+   * <p>{@code kushGaugeBitrate = height * width * frameRate * 0.07 * motionFactor}.
+   *
+   * <p>Motion factors:
+   *
+   * <ul>
+   *   <li>Low motion video - 1
+   *   <li>Medium motion video - 2
+   *   <li>High motion video - 4
+   * </ul>
+   */
   private static int getSuggestedBitrate(int width, int height, float frameRate) {
     // TODO(b/210591626) Implement bitrate estimation.
-    // 1080p30 -> 6.2Mbps, 720p30 -> 2.7Mbps.
-    return (int) (width * height * frameRate * 0.1);
+    // Assume medium motion factor.
+    // 1080p60 -> 16.6Mbps, 720p30 -> 3.7Mbps.
+    return (int) (width * height * frameRate * 0.07 * 2);
   }
 
   @RequiresNonNull("#1.sampleMimeType")

library/transformer/src/test/java/com/google/android/exoplayer2/transformer/DefaultEncoderFactoryTest.java

@@ -74,8 +74,8 @@ public class DefaultEncoderFactoryTest {
     assertThat(actualVideoFormat.sampleMimeType).isEqualTo(MimeTypes.VIDEO_H264);
     assertThat(actualVideoFormat.width).isEqualTo(1920);
     assertThat(actualVideoFormat.height).isEqualTo(1080);
-    // 1920 * 1080 * 30 * 0.1
-    assertThat(actualVideoFormat.averageBitrate).isEqualTo(6_220_800);
+    // 1920 * 1080 * 30 * 0.07 * 2.
+    assertThat(actualVideoFormat.averageBitrate).isEqualTo(8_709_120);
   }
 
   @Test
@@ -92,8 +92,8 @@ public class DefaultEncoderFactoryTest {
     assertThat(actualVideoFormat.sampleMimeType).isEqualTo(MimeTypes.VIDEO_H264);
     assertThat(actualVideoFormat.width).isEqualTo(1920);
     assertThat(actualVideoFormat.height).isEqualTo(1080);
-    // 1920 * 1080 * 30 * 0.1
-    assertThat(actualVideoFormat.averageBitrate).isEqualTo(6_220_800);
+    // 1920 * 1080 * 30 * 0.07 * 2.
+    assertThat(actualVideoFormat.averageBitrate).isEqualTo(8_709_120);
   }
 
   @Test