Add libopus/libvpx availability checks

extensions/opus/src/main/java/com/google/android/exoplayer/ext/opus/LibopusAudioTrackRenderer.java

@@ -120,12 +120,19 @@ public final class LibopusAudioTrackRenderer extends SampleSourceTrackRenderer
   }
 
   /**
+   * Returns whether the underlying libopus library is available.
+   */
+  public static boolean isLibopusAvailable() {
+    return OpusDecoder.isLibopusAvailable();
+  }
+
+  /**
    * Get the version of underlying libopus library.
    *
    * @return version of the underlying libopus library.
    */
   public static String getLibopusVersion() {
-    return OpusDecoder.getLibopusVersion();
+    return isLibopusAvailable() ? OpusDecoder.getLibopusVersion() : null;
   }
 
   @Override

extensions/opus/src/main/java/com/google/android/exoplayer/ext/opus/OpusDecoder.java

@@ -26,13 +26,21 @@ import java.nio.ByteBuffer;
  */
 /* package */ class OpusDecoder {
 
-  private final long nativeDecoderContext;
-
+  private static final boolean IS_AVAILABLE;
   static {
+    boolean isAvailable;
+    try {
       System.loadLibrary("opus");
       System.loadLibrary("opusJNI");
+      isAvailable = true;
+    } catch (UnsatisfiedLinkError exception) {
+      isAvailable = false;
+    }
+    IS_AVAILABLE = isAvailable;
   }
 
+  private final long nativeDecoderContext;
+
   /**
    * Creates the Opus Decoder.
    *
@@ -82,6 +90,13 @@ import java.nio.ByteBuffer;
   }
 
   /**
+   * Returns whether the underlying libopus library is available.
+   */
+  public static boolean isLibopusAvailable() {
+    return IS_AVAILABLE;
+  }
+
+  /**
    * Returns the version string of the underlying libopus decoder.
    */
   public static native String getLibopusVersion();

extensions/vp9/src/main/java/com/google/android/exoplayer/ext/vp9/LibvpxVideoTrackRenderer.java

@@ -151,12 +151,17 @@ public final class LibvpxVideoTrackRenderer extends SampleSourceTrackRenderer {
   }
 
   /**
-   * Get the version of underlying libvpx library.
-   *
-   * @return version of the underlying libvpx library.
+   * Returns whether the underlying libvpx library is available.
+   */
+  public static boolean isLibvpxAvailable() {
+    return VpxDecoder.isLibvpxAvailable();
+  }
+
+  /**
+   * Returns the version of the underlying libvpx library if available, otherwise {@code null}.
    */
   public static String getLibvpxVersion() {
-    return VpxDecoder.getLibvpxVersion();
+    return isLibvpxAvailable() ? VpxDecoder.getLibvpxVersion() : null;
   }
 
   @Override

extensions/vp9/src/main/java/com/google/android/exoplayer/ext/vp9/VpxDecoder.java

@@ -24,13 +24,21 @@ import java.nio.ByteBuffer;
  */
 /* package */ class VpxDecoder {
 
-  private final long vpxDecContext;
-
+  private static final boolean IS_AVAILABLE;
   static {
+    boolean isAvailable;
+    try {
       System.loadLibrary("vpx");
       System.loadLibrary("vpxJNI");
+      isAvailable = true;
+    } catch (UnsatisfiedLinkError exception) {
+      isAvailable = false;
+    }
+    IS_AVAILABLE = isAvailable;
   }
 
+  private final long vpxDecContext;
+
   /**
    * Creates the VP9 Decoder.
    *
@@ -70,6 +78,13 @@ import java.nio.ByteBuffer;
   }
 
   /**
+   * Returns whether the underlying libvpx library is available.
+   */
+  public static boolean isLibvpxAvailable() {
+    return IS_AVAILABLE;
+  }
+
+  /**
    * Returns the version string of the underlying libvpx decoder.
    */
   public static native String getLibvpxVersion();