编译google libyuv so库

libyuv是Google开源的实现各种YUV与RGB之间相互转换、旋转、缩放的库。支持在Windows、Linux、Mac、等平台 和x86、x64、arm架构上进行编译执行，支持SSE、AVX、NEON等SIMD指令加速。
##下载

下载地址：
https://code.google.com/p/libyuv/source/checkout
或者
https://github.com/lemenkov/libyuv

##编译

ubuntu 下编译：

• android-ndk-r13b
• git

下载：

git clone https://github.com/lemenkov/libyuv.git

下载后是libyuv，其目录如下：

配置ndk环境

gedit .bashrc
//在里面添加ndk环境如下
export PATH="/home/lammy/ffmpeg/android-ndk-r13b/:$PATH"
source .bashrc

新建jni目录
按其他博客说的只需要执行 ndk-build就可以了，但我执行一直报错：

Android NDK: Could not find application project directory !    
Android NDK: Please define the NDK_PROJECT_PATH variable to point to it.    
/home/lammy/ffmpeg/android-ndk-r13b/build/core/build-local.mk:151: *** Android NDK: 
Aborting    .  Stop.

后来查了很多资料后才得知，ndk只编译jin，所以在libyuv 下面新建了jni目录，然后将所有文件拷贝进去。

修改Android.mk文件

将LOCAL_MODULE := libyuv-static 替换为LOCAL_MODULE := libyuv（这里只是修改编译的库名，可不操作）
将include $(BUILD_STATIC_LIBRARY) 替换为include $(BUILD_SHARED_LIBRARY)

# This is the Android makefile for libyuv for both platform and NDK.
LOCAL_PATH:= $(call my-dir)

include $(CLEAR_VARS)

LOCAL_CPP_EXTENSION := .cc

LOCAL_SRC_FILES := \
    source/compare.cc           \
    source/compare_common.cc    \
    source/compare_neon64.cc    \
    source/compare_gcc.cc       \
    source/convert.cc           \
    source/convert_argb.cc      \
    source/convert_from.cc      \
    source/convert_from_argb.cc \
    source/convert_to_argb.cc   \
    source/convert_to_i420.cc   \
    source/cpu_id.cc            \
    source/planar_functions.cc  \
    source/rotate.cc            \
    source/rotate_any.cc        \
    source/rotate_argb.cc       \
    source/rotate_common.cc     \
    source/rotate_mips.cc       \
    source/rotate_neon64.cc     \
    source/rotate_gcc.cc        \
    source/row_any.cc           \
    source/row_common.cc        \
    source/row_mips.cc          \
    source/row_neon64.cc        \
    source/row_gcc.cc	        \
    source/scale.cc             \
    source/scale_any.cc         \
    source/scale_argb.cc        \
    source/scale_common.cc      \
    source/scale_mips.cc        \
    source/scale_neon64.cc      \
    source/scale_gcc.cc         \
    source/video_common.cc

# TODO(fbarchard): Enable mjpeg encoder.
#   source/mjpeg_decoder.cc
#   source/convert_jpeg.cc
#   source/mjpeg_validate.cc

ifeq ($(TARGET_ARCH_ABI),armeabi-v7a)
    LOCAL_CFLAGS += -DLIBYUV_NEON
    LOCAL_SRC_FILES += \
        source/compare_neon.cc.neon    \
        source/rotate_neon.cc.neon     \
        source/row_neon.cc.neon        \
        source/scale_neon.cc.neon
endif

LOCAL_EXPORT_C_INCLUDES := $(LOCAL_PATH)/include
LOCAL_C_INCLUDES += $(LOCAL_PATH)/include

#LOCAL_MODULE := libyuv-static
LOCAL_MODULE := libyuv
LOCAL_MODULE_TAGS := optional

# include $(BUILD_STATIC_LIBRARY)
include $(BUILD_SHARED_LIBRARY)

然后回到libyuv目录执行：

ndk-build clean
ndk-build

则可以看到生成objec和lib目录

libs下就是我们编译的库文件

在android上为了使用，我们得将jni/include/libyuv 目录拷贝出来，是头文件和so一起，方便ndk 底层c使用。
这里给出我编译好的so和头文件压缩包，欢迎各位老铁下载。