Use CMake to build the ffmpeg audio extension

PiperOrigin-RevId: 322793308

extensions/ffmpeg/README.md

@@ -18,8 +18,8 @@ its modules locally. Instructions for doing this can be found in ExoPlayer's
 [top level README][]. The extension is not provided via JCenter (see [#2781][]
 for more information).
 
-In addition, it's necessary to build the extension's native components as
+In addition, it's necessary to manually build the FFmpeg library, so that gradle
-follows:
+can bundle the FFmpeg binaries in the APK:
 
 * Set the following shell variable:
 
@@ -73,14 +73,6 @@ cd "${FFMPEG_EXT_PATH}/jni" && \
   "${FFMPEG_EXT_PATH}" "${NDK_PATH}" "${HOST_PLATFORM}" "${ENABLED_DECODERS[@]}"
 ```
 
-* Build the JNI native libraries, setting `APP_ABI` to include the architectures
-  built in the previous step. For example:
-
-```
-cd "${FFMPEG_EXT_PATH}/jni" && \
-${NDK_PATH}/ndk-build APP_ABI="armeabi-v7a arm64-v8a x86 x86_64" -j4
-```
-
 ## Build instructions (Windows) ##
 
 We do not provide support for building this extension on Windows, however it

extensions/ffmpeg/build.gradle

@@ -15,11 +15,18 @@ apply from: "$gradle.ext.exoplayerSettingsDir/common_library_config.gradle"
 
 android {
     sourceSets.main {
+        // The directory from which to pick the ffmpeg binaries.
         jniLibs.srcDir 'src/main/libs'
-        jni.srcDirs = [] // Disable the automatic ndk-build call by Android Studio.
     }
 }
 
+// Configure the native build only if ffmpeg is present to avoid gradle sync
+// failures if ffmpeg hasn't been built according to the README instructions.
+if (project.file('src/main/jni/ffmpeg').exists()) {
+    android.externalNativeBuild.cmake.path = 'src/main/jni/CMakeLists.txt'
+    android.externalNativeBuild.cmake.version = '3.7.1+'
+}
+
 dependencies {
     implementation project(modulePrefix + 'library-core')
     implementation 'androidx.annotation:annotation:' + androidxAnnotationVersion

extensions/ffmpeg/src/main/java/com/google/android/exoplayer2/ext/ffmpeg/FfmpegLibrary.java

@@ -35,7 +35,7 @@ public final class FfmpegLibrary {
   private static final String TAG = "FfmpegLibrary";
 
   private static final LibraryLoader LOADER =
-      new LibraryLoader("avutil", "swresample", "avcodec", "ffmpeg");
+      new LibraryLoader("avutil", "swresample", "avcodec", "ffmpeg_jni");
 
   private static @MonotonicNonNull String version;
   private static int inputBufferPaddingSize = C.LENGTH_UNSET;

extensions/ffmpeg/src/main/jni/Android.mk

@@ -1,40 +0,0 @@
-#
-# 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.
-#
-
-LOCAL_PATH := $(call my-dir)
-
-include $(CLEAR_VARS)
-LOCAL_MODULE    := libavcodec
-LOCAL_SRC_FILES := ffmpeg/android-libs/$(TARGET_ARCH_ABI)/$(LOCAL_MODULE).so
-include $(PREBUILT_SHARED_LIBRARY)
-
-include $(CLEAR_VARS)
-LOCAL_MODULE    := libswresample
-LOCAL_SRC_FILES := ffmpeg/android-libs/$(TARGET_ARCH_ABI)/$(LOCAL_MODULE).so
-include $(PREBUILT_SHARED_LIBRARY)
-
-include $(CLEAR_VARS)
-LOCAL_MODULE    := libavutil
-LOCAL_SRC_FILES := ffmpeg/android-libs/$(TARGET_ARCH_ABI)/$(LOCAL_MODULE).so
-include $(PREBUILT_SHARED_LIBRARY)
-
-include $(CLEAR_VARS)
-LOCAL_MODULE := ffmpeg
-LOCAL_SRC_FILES := ffmpeg_jni.cc
-LOCAL_C_INCLUDES := ffmpeg
-LOCAL_SHARED_LIBRARIES := libavcodec libswresample libavutil
-LOCAL_LDLIBS := -Lffmpeg/android-libs/$(TARGET_ARCH_ABI) -llog
-include $(BUILD_SHARED_LIBRARY)

extensions/ffmpeg/src/main/jni/Application.mk

@@ -1,20 +0,0 @@
-#
-# 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.
-#
-
-APP_OPTIM := release
-APP_STL := c++_static
-APP_CPPFLAGS := -frtti
-APP_PLATFORM := android-9

extensions/ffmpeg/src/main/jni/CMakeLists.txt

@@ -0,0 +1,38 @@
+cmake_minimum_required(VERSION 3.7.1 FATAL_ERROR)
+
+# Enable C++11 features.
+set(CMAKE_CXX_STANDARD 11)
+
+project(libffmpeg_jni C CXX)
+
+set(ffmpeg_location "${CMAKE_CURRENT_SOURCE_DIR}/ffmpeg")
+set(ffmpeg_binaries "${ffmpeg_location}/android-libs/${ANDROID_ABI}")
+set(ffmpeg_output_dir "${CMAKE_CURRENT_SOURCE_DIR}/../libs/${ANDROID_ABI}")
+
+foreach(ffmpeg_lib avutil swresample avcodec)
+    set(ffmpeg_lib_filename lib${ffmpeg_lib}.so)
+    set(ffmpeg_lib_file_path ${ffmpeg_binaries}/${ffmpeg_lib_filename})
+    add_library(
+            ${ffmpeg_lib}
+            SHARED
+            IMPORTED)
+    set_target_properties(
+            ${ffmpeg_lib} PROPERTIES
+            IMPORTED_LOCATION
+            ${ffmpeg_lib_file_path})
+    file(COPY ${ffmpeg_lib_file_path} DESTINATION ${ffmpeg_output_dir})
+endforeach()
+
+include_directories(${ffmpeg_location})
+find_library(android_log_lib log)
+
+add_library(ffmpeg_jni
+            SHARED
+            ffmpeg_jni.cc)
+
+target_link_libraries(ffmpeg_jni
+                      PRIVATE android
+                      PRIVATE avutil
+                      PRIVATE swresample
+                      PRIVATE avcodec
+                      PRIVATE ${android_log_lib})