android UVC h264 ffmpeg硬解碼（RK3288 android5.1）
username需求：由於軟解碼速度跟不上導致解碼花屏嚴重，轉用ffmpeg交叉編譯android 5.1原始碼硬解碼。
假設已經編譯好RK3288 android5.1系統（主要是硬編碼用到的libstagefright庫）
系統編譯參考：https://blog.csdn.net/pizziars/article/details/83176742
修改ffmpeg-2.2/configure檔案
如果直接按照未修改的配置進行編譯，結果編譯出來的so檔案類似libavcodec.so.55.39.101，版本號位於so之後，Android上似乎無法載入。因此需要按如下修改：
將該檔案中的如下四行：
SLIBNAME_WITH_MAJOR='$(SLIBNAME).$(LIBMAJOR)'
LIB_INSTALL_EXTRA_CMD='$$(RANLIB)"$(LIBDIR)/$(LIBNAME)"'
SLIB_INSTALL_NAME='$(SLIBNAME_WITH_VERSION)'
SLIB_INSTALL_LINKS='$(SLIBNAME_WITH_MAJOR)$(SLIBNAME)'
替換為：
SLIBNAME_WITH_MAJOR='$(SLIBPREF)$(FULLNAME)-$(LIBMAJOR)$(SLIBSUF)'
LIB_INSTALL_EXTRA_CMD='$$(RANLIB)"$(LIBDIR)/$(LIBNAME)"'
SLIB_INSTALL_NAME='$(SLIBNAME_WITH_MAJOR)'
SLIB_INSTALL_LINKS='$(SLIBNAME)'
另外（硬編碼相關，否則提示 ERROR: libstagefright_h264 not found）：
enabled libstagefright_h264 && require_cpp libstagefright_h264 "binder/ProcessState.h media/stagefright/MetaData.h
media/stagefright/MediaBufferGroup.h media/stagefright/MediaDebug.h media/stagefright/MediaDefs.h
media/stagefright/OMXClient.h media/stagefright/OMXCodec.h" android::OMXClient -lstagefright -lmedia -lutils -lbinder -lgnustl_static
修改為
enabled libstagefright && require_cpp libstagefright_h264 "binder/ProcessState.h media/stagefright/MetaData.h
media/stagefright/MediaBufferGroup.h media/stagefright/MediaDebug.h media/stagefright/MediaDefs.h
media/stagefright/OMXClient.h media/stagefright/OMXCodec.h" android::OMXClient -lstagefright -lmedia -lutils -lbinder -lgnustl_static
編寫config_android.sh指令碼檔案
config_android.sh的內容如下：
#!/bin/bash
export NDK=/home/username/ffmpeg/android-ndk-r9d
SYSROOT=$NDK/platforms/android-9/arch-arm/
TOOLCHAIN=$NDK/toolchains/arm-linux-androideabi-4.8/prebuilt/linux-x86_64
#git clone --depth=1 --branch gingerbread-release https://github.com/CyanogenMod/android_frameworks_base.git ../android-source/frameworks/base
#git clone --depth=1 --branch gingerbread-release https://github.com/CyanogenMod/android_system_core.git ../android-source/system/core
# Libraries from any froyo/gingerbread device/emulator should work
# fine, since the symbols used should be available on most of them.
#if [ ! -d "../android-libs" ]; then
# if [ ! -f "../update-cm-7.0.3-N1-signed.zip" ]; then
# wget http://download.cyanogenmod.com/get/update-cm-7.0.3-N1-signed.zip -P../
# fi
# unzip ../update-cm-7.0.3-N1-signed.zip system/lib/* -d../
# mv ../system/lib ../android-libs
# rmdir ../system
#fi
function build_one
{
./configure \
--prefix=$PREFIX \
--enable-shared \
--disable-static \
--enable-libstagefright-h264 \
--disable-doc \
--disable-ffserver \
--enable-cross-compile \
--cross-prefix=$TOOLCHAIN/bin/arm-linux-androideabi- \
--target-os=linux \
--arch=arm \
--sysroot=$SYSROOT \
--extra-cflags="-Os -fpic $ADDI_CFLAGS $EXTRA_CFLAGS" \
--extra-ldflags="$ADDI_LDFLAGS $EXTRA_LDFLAGS" \
--extra-cxxflags="$EXTRA_CXXFLAGS" \
$ADDITIONAL_CONFIGURE_FLAG
}
ANDROID_SOURCE=/home/username/rk
ANDROID_LIBS=/home/username/rk/out/target/product/rk3288_box/system/lib
ABI="armeabi-v7a"
EXTRA_CFLAGS="-I$ANDROID_SOURCE/frameworks/base/include -I$ANDROID_SOURCE/system/core/include"
EXTRA_CFLAGS="$EXTRA_CFLAGS -I$ANDROID_SOURCE/frameworks/native/include"
EXTRA_CFLAGS="$EXTRA_CFLAGS -I$ANDROID_SOURCE/frameworks/av/include"
EXTRA_CFLAGS="$EXTRA_CFLAGS -I$ANDROID_SOURCE/hardware/libhardware/include"
EXTRA_CFLAGS="$EXTRA_CFLAGS -I$ANDROID_SOURCE/frameworks/native/include/media/openmax"
EXTRA_CFLAGS="$EXTRA_CFLAGS -I$ANDROID_SOURCE/frameworks/base/media/libstagefright"
EXTRA_CFLAGS="$EXTRA_CFLAGS -I$ANDROID_SOURCE/frameworks/base/include/media/stagefright/openmax"
EXTRA_CFLAGS="$EXTRA_CFLAGS -I$NDK/sources/cxx-stl/gnu-libstdc++/4.8/include -I$NDK/sources/cxx-stl/gnu-libstdc++/4.8/libs/$ABI/include"
EXTRA_CFLAGS="$EXTRA_CFLAGS -march=armv7-a -mfloat-abi=softfp -mfpu=neon"
EXTRA_LDFLAGS="-Wl,--fix-cortex-a8 -L$ANDROID_LIBS -Wl,-rpath-link,$ANDROID_LIBS -L$NDK/sources/cxx-stl/gnu-libstdc++/4.8/libs/$ABI -lstagefright -lstdc++ -lutils -lbinder -lgnustl_static -lgnustl_shared"
#EXTRA_LDFLAGS="-Wl,--fix-cortex-a8 -L$ANDROID_LIBS -Wl,-rpath-link,$ANDROID_LIBS -L$NDK/sources/cxx-stl/gnu-libstdc++/4.8/libs/$ABI -#lstagefright -lstdc++ -lutils -lbinder"
EXTRA_CXXFLAGS="-Wno-multichar -fno-exceptions -fno-rtti"
CPU=armeabi-v7a
PREFIX=$(pwd)/android/$CPU
ADDI_CFLAGS="-marm"
build_one
#make clean
#make -j6 || exit 1
給config_android.sh增加可執行許可權：
$chmod +x config_android.sh
執行config_android.sh
$./config_android.sh
修改剛剛生成的檔案config.h：
#define HAVE_LOG2 1
#define HAVE_LOG2F 1
#define HAVE_POSIX_MEMALIGN 1
修改為
#define HAVE_LOG2 0
#define HAVE_LOG2F 0
#define HAVE_POSIX_MEMALIGN 0
修改檔案/libavcodec/libstagefright.cpp（註釋掉#include <media/stagefright/MediaDebug.h>）：
//#include <media/stagefright/MediaDebug.h>
編譯：
make -j6
至此編譯完成
參考資料：