Add support to VP9 extension for overriding the native library names

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=132874777

extensions/vp9/src/main/java/com/google/android/exoplayer2/ext/vp9/LibvpxVideoRenderer.java

@@ -116,30 +116,10 @@ public final class LibvpxVideoRenderer extends BaseRenderer {
     outputMode = VpxDecoder.OUTPUT_MODE_NONE;
   }
 
-  /**
-   * Returns whether the underlying libvpx library is available.
-   */
-  public static boolean isLibvpxAvailable() {
-    return VpxDecoder.IS_AVAILABLE;
-  }
-
-  /**
-   * Returns the version of the underlying libvpx library if available, otherwise {@code null}.
-   */
-  public static String getLibvpxVersion() {
-    return isLibvpxAvailable() ? VpxDecoder.getLibvpxVersion() : null;
-  }
-
-  /**
-   * Returns the configuration string with which the underlying libvpx library was built.
-   */
-  public static String getLibvpxConfig() {
-    return isLibvpxAvailable() ? VpxDecoder.getLibvpxConfig() : null;
-  }
-
   @Override
   public int supportsFormat(Format format) {
-    return isLibvpxAvailable() && MimeTypes.VIDEO_VP9.equalsIgnoreCase(format.sampleMimeType)
+    return VpxNativeLibraryHelper.isLibvpxAvailable()
+        && MimeTypes.VIDEO_VP9.equalsIgnoreCase(format.sampleMimeType)
         ? (FORMAT_HANDLED | ADAPTIVE_SEAMLESS) : FORMAT_UNSUPPORTED_TYPE;
   }
 

extensions/vp9/src/main/java/com/google/android/exoplayer2/ext/vp9/VpxDecoder.java

@@ -30,32 +30,6 @@ import java.nio.ByteBuffer;
   public static final int OUTPUT_MODE_YUV = 0;
   public static final int OUTPUT_MODE_RGB = 1;
 
-  /**
-   * Whether the underlying libvpx library is available.
-   */
-  public 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;
-  }
-
-  /**
-   * Returns the version string of the underlying libvpx decoder.
-   */
-  public static native String getLibvpxVersion();
-
-  /**
-   * Returns the configuration string with which the underlying libvpx library was built.
-   */
-  public static native String getLibvpxConfig();
-
   private final long vpxDecContext;
 
   private volatile int outputMode;
@@ -71,6 +45,9 @@ import java.nio.ByteBuffer;
   public VpxDecoder(int numInputBuffers, int numOutputBuffers, int initialInputBufferSize)
       throws VpxDecoderException {
     super(new DecoderInputBuffer[numInputBuffers], new VpxOutputBuffer[numOutputBuffers]);
+    if (!VpxNativeLibraryHelper.isLibvpxAvailable()) {
+      throw new VpxDecoderException("Failed to load decoder native libraries.");
+    }
     vpxDecContext = vpxInit();
     if (vpxDecContext == 0) {
       throw new VpxDecoderException("Failed to initialize decoder");
@@ -80,7 +57,7 @@ import java.nio.ByteBuffer;
 
   @Override
   public String getName() {
-    return "libvpx" + getLibvpxVersion();
+    return "libvpx" + VpxNativeLibraryHelper.getLibvpxVersion();
   }
 
   /**
@@ -134,5 +111,4 @@ import java.nio.ByteBuffer;
   private native long vpxDecode(long context, ByteBuffer encoded, int length);
   private native int vpxGetFrame(long context, VpxOutputBuffer outputBuffer);
   private native String vpxGetErrorMessage(long context);
-
 }

extensions/vp9/src/main/java/com/google/android/exoplayer2/ext/vp9/VpxNativeLibraryHelper.java

@@ -0,0 +1,88 @@
+/*
+ * Copyright (C) 2016 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.google.android.exoplayer2.ext.vp9;
+
+import com.google.android.exoplayer2.util.Assertions;
+
+/**
+ * Configure the native libraries that are used by the {@link VpxDecoder}.
+ */
+public final class VpxNativeLibraryHelper {
+
+  private static boolean loadAttempted;
+  private static boolean isAvailable;
+  private static String[] nativeLibs = { "vpx", "vpxJNI" };
+
+  private static final Object lock = new Object();
+
+  private VpxNativeLibraryHelper() {}
+
+  /**
+   * Override the default set of native libraries loaded for Vpx decoder support.
+   * If an application wishes to call this method, it must do so before calling any other method
+   * defined by this class, and before instantiating a {@link LibvpxVideoRenderer} instance.
+   */
+  public static void setNativeLibraries(String... libs) {
+    synchronized (lock) {
+      Assertions.checkState(!loadAttempted,
+          "Vpx native libs must be set earlier, they have already been loaded.");
+      nativeLibs = libs;
+    }
+  }
+
+  /**
+   * Returns whether the underlying libvpx library is available.
+   */
+  public static boolean isLibvpxAvailable() {
+    return loadNativeLibraries();
+  }
+
+  /**
+   * Returns the version of the underlying libvpx library if available, otherwise {@code null}.
+   */
+  public static String getLibvpxVersion() {
+    return isLibvpxAvailable() ? nativeGetLibvpxConfig() : null;
+  }
+
+  /**
+   * Returns the configuration string with which the underlying libvpx library was built.
+   */
+  public static String getLibvpxConfig() {
+    return isLibvpxAvailable() ? nativeGetLibvpxVersion() : null;
+  }
+
+  private static boolean loadNativeLibraries() {
+    synchronized (lock) {
+      if (loadAttempted) {
+        return isAvailable;
+      }
+
+      loadAttempted = true;
+      try {
+        for (String lib : VpxNativeLibraryHelper.nativeLibs) {
+          System.loadLibrary(lib);
+        }
+        isAvailable = true;
+      } catch (UnsatisfiedLinkError exception) {
+        isAvailable = false;
+      }
+      return isAvailable;
+    }
+  }
+
+  private static native String nativeGetLibvpxConfig();
+  private static native String nativeGetLibvpxVersion();
+}

extensions/vp9/src/main/jni/vpx_jni.cc

@@ -34,7 +34,7 @@
 #define LOGE(...) ((void)__android_log_print(ANDROID_LOG_ERROR, LOG_TAG, \
                                              __VA_ARGS__))
 
-#define FUNC(RETURN_TYPE, NAME, ...) \
+#define VPX_DECODER_FUNC(RETURN_TYPE, NAME, ...) \
   extern "C" { \
   JNIEXPORT RETURN_TYPE \
     Java_com_google_android_exoplayer2_ext_vp9_VpxDecoder_ ## NAME \
@@ -44,6 +44,16 @@
     Java_com_google_android_exoplayer2_ext_vp9_VpxDecoder_ ## NAME \
       (JNIEnv* env, jobject thiz, ##__VA_ARGS__)\
 
+#define VPX_NATIVE_LIBRARY_HELPER_FUNC(RETURN_TYPE, NAME, ...) \
+  extern "C" { \
+  JNIEXPORT RETURN_TYPE \
+    Java_com_google_android_exoplayer2_ext_vp9_VpxNativeLibraryHelper_ ## NAME \
+      (JNIEnv* env, jobject thiz, ##__VA_ARGS__);\
+  } \
+  JNIEXPORT RETURN_TYPE \
+    Java_com_google_android_exoplayer2_ext_vp9_VpxNativeLibraryHelper_ ## NAME \
+      (JNIEnv* env, jobject thiz, ##__VA_ARGS__)\
+
 // JNI references for VpxOutputBuffer class.
 static jmethodID initForRgbFrame;
 static jmethodID initForYuvFrame;
@@ -58,7 +68,7 @@ jint JNI_OnLoad(JavaVM* vm, void* reserved) {
   return JNI_VERSION_1_6;
 }
 
-FUNC(jlong, vpxInit) {
+VPX_DECODER_FUNC(jlong, vpxInit) {
   vpx_codec_ctx_t* context = new vpx_codec_ctx_t();
   vpx_codec_dec_cfg_t cfg = {0, 0, 0};
   cfg.threads = android_getCpuCount();
@@ -81,7 +91,7 @@ FUNC(jlong, vpxInit) {
   return reinterpret_cast<intptr_t>(context);
 }
 
-FUNC(jlong, vpxDecode, jlong jContext, jobject encoded, jint len) {
+VPX_DECODER_FUNC(jlong, vpxDecode, jlong jContext, jobject encoded, jint len) {
   vpx_codec_ctx_t* const context = reinterpret_cast<vpx_codec_ctx_t*>(jContext);
   const uint8_t* const buffer =
       reinterpret_cast<const uint8_t*>(env->GetDirectBufferAddress(encoded));
@@ -94,14 +104,14 @@ FUNC(jlong, vpxDecode, jlong jContext, jobject encoded, jint len) {
   return 0;
 }
 
-FUNC(jlong, vpxClose, jlong jContext) {
+VPX_DECODER_FUNC(jlong, vpxClose, jlong jContext) {
   vpx_codec_ctx_t* const context = reinterpret_cast<vpx_codec_ctx_t*>(jContext);
   vpx_codec_destroy(context);
   delete context;
   return 0;
 }
 
-FUNC(jint, vpxGetFrame, jlong jContext, jobject jOutputBuffer) {
+VPX_DECODER_FUNC(jint, vpxGetFrame, jlong jContext, jobject jOutputBuffer) {
   vpx_codec_ctx_t* const context = reinterpret_cast<vpx_codec_ctx_t*>(jContext);
   vpx_codec_iter_t iter = NULL;
   const vpx_image_t* const img = vpx_codec_get_frame(context, &iter);
@@ -166,15 +176,16 @@ FUNC(jint, vpxGetFrame, jlong jContext, jobject jOutputBuffer) {
   return 0;
 }
 
-FUNC(jstring, getLibvpxVersion) {
+VPX_DECODER_FUNC(jstring, vpxGetErrorMessage, jlong jContext) {
-  return env->NewStringUTF(vpx_codec_version_str());
-}
-
-FUNC(jstring, getLibvpxConfig) {
-  return env->NewStringUTF(vpx_codec_build_config());
-}
-
-FUNC(jstring, vpxGetErrorMessage, jlong jContext) {
   vpx_codec_ctx_t* const context = reinterpret_cast<vpx_codec_ctx_t*>(jContext);
   return env->NewStringUTF(vpx_codec_error(context));
 }
+
+VPX_NATIVE_LIBRARY_HELPER_FUNC(jstring, nativeGetLibvpxVersion) {
+  return env->NewStringUTF(vpx_codec_version_str());
+}
+
+VPX_NATIVE_LIBRARY_HELPER_FUNC(jstring, nativeGetLibvpxConfig) {
+  return env->NewStringUTF(vpx_codec_build_config());
+}
+