Use API level 23 constants.

library/src/main/java/com/google/android/exoplayer/C.java

@@ -70,19 +70,24 @@ public final class C {
   @SuppressWarnings("InlinedApi")
   public static final int ENCODING_E_AC3 = AudioFormat.ENCODING_E_AC3;
 
-  // TODO: Switch these constants to use AudioFormat fields when the target API version is >= 23.
-  // The inlined values here are for NVIDIA Shield devices which support DTS on earlier versions.
-  public static final int ENCODING_DTS = 7;
-  public static final int ENCODING_DTS_HD = 8;
+  /**
+   * @see AudioFormat#ENCODING_DTS
+   */
+  @SuppressWarnings("InlinedApi")
+  public static final int ENCODING_DTS = AudioFormat.ENCODING_DTS;
+
+  /**
+   * @see AudioFormat#ENCODING_DTS_HD
+   */
+  @SuppressWarnings("InlinedApi")
+  public static final int ENCODING_DTS_HD = AudioFormat.ENCODING_DTS_HD;
 
-  // TODO: Change 6396 to AudioFormat.CHANNEL_OUT_7POINT1_SURROUND when the target API version is
-  // >= 23.
   /**
    * @see AudioFormat#CHANNEL_OUT_7POINT1_SURROUND
    */
   @SuppressWarnings({"InlinedApi", "deprecation"})
   public static final int CHANNEL_OUT_7POINT1_SURROUND = Util.SDK_INT < 23
-      ? AudioFormat.CHANNEL_OUT_7POINT1 : 6396;
+      ? AudioFormat.CHANNEL_OUT_7POINT1 : AudioFormat.CHANNEL_OUT_7POINT1_SURROUND;
 
   /**
    * @see MediaExtractor#SAMPLE_FLAG_SYNC