# ExoPlayer FFmpeg extension #

## Description ##

The FFmpeg extension is a [Renderer][] implementation that uses FFmpeg to decode
audio.

[Renderer]: https://google.github.io/ExoPlayer/doc/reference/com/google/android/exoplayer2/Renderer.html

## Build instructions ##

To use this extension you need to clone the ExoPlayer repository and depend on
its modules locally. Instructions for doing this can be found in ExoPlayer's
[top level README][]. In addition, it's necessary to build the extension's
native components as follows:

* Set the following environment variables:

```
cd "<path to exoplayer checkout>"
EXOPLAYER_ROOT="$(pwd)"
FFMPEG_EXT_PATH="${EXOPLAYER_ROOT}/extensions/ffmpeg/src/main"
```

* Download the [Android NDK][] and set its location in an environment variable:

```
NDK_PATH="<path to Android NDK>"
```

* Set up host platform ("darwin-x86_64" for Mac OS X):

```
HOST_PLATFORM="linux-x86_64"
```

* Fetch and build FFmpeg. For example, to fetch and build for armeabi-v7a,
  arm64-v8a and x86 on Linux x86_64:

```
COMMON_OPTIONS="\
    --target-os=android \
    --disable-static \
    --enable-shared \
    --disable-doc \
    --disable-programs \
    --disable-everything \
    --disable-avdevice \
    --disable-avformat \
    --disable-swscale \
    --disable-postproc \
    --disable-avfilter \
    --disable-symver \
    --disable-swresample \
    --enable-avresample \
    --enable-decoder=vorbis \
    --enable-decoder=opus \
    --enable-decoder=flac \
    " && \
cd "${FFMPEG_EXT_PATH}/jni" && \
git clone git://source.ffmpeg.org/ffmpeg ffmpeg && cd ffmpeg && \
./configure \
    --libdir=android-libs/armeabi-v7a \
    --arch=arm \
    --cpu=armv7-a \
    --cross-prefix="${NDK_PATH}/toolchains/arm-linux-androideabi-4.9/prebuilt/${HOST_PLATFORM}/bin/arm-linux-androideabi-" \
    --sysroot="${NDK_PATH}/platforms/android-9/arch-arm/" \
    --extra-cflags="-march=armv7-a -mfloat-abi=softfp" \
    --extra-ldflags="-Wl,--fix-cortex-a8" \
    --extra-ldexeflags=-pie \
    ${COMMON_OPTIONS} \
    && \
make -j4 && make install-libs && \
make clean && ./configure \
    --libdir=android-libs/arm64-v8a \
    --arch=aarch64 \
    --cpu=armv8-a \
    --cross-prefix="${NDK_PATH}/toolchains/aarch64-linux-android-4.9/prebuilt/${HOST_PLATFORM}/bin/aarch64-linux-android-" \
    --sysroot="${NDK_PATH}/platforms/android-21/arch-arm64/" \
    --extra-ldexeflags=-pie \
    ${COMMON_OPTIONS} \
    && \
make -j4 && make install-libs && \
make clean && ./configure \
    --libdir=android-libs/x86 \
    --arch=x86 \
    --cpu=i686 \
    --cross-prefix="${NDK_PATH}/toolchains/x86-4.9/prebuilt/${HOST_PLATFORM}/bin/i686-linux-android-" \
    --sysroot="${NDK_PATH}/platforms/android-9/arch-x86/" \
    --extra-ldexeflags=-pie \
    --disable-asm \
    ${COMMON_OPTIONS} \
    && \
make -j4 && make install-libs && \
make clean
```

* 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" -j4
```

[top level README]: https://github.com/google/ExoPlayer/blob/release-v2/README.md
[Android NDK]: https://developer.android.com/tools/sdk/ndk/index.html