1. 说明
至于libyuv[1]的用途，就不赘述了。以下是官方说明
Scale YUV to prepare content for compression, with point, bilinear or box filter.
Convert to YUV from webcam formats for compression.
Convert to RGB formats for rendering/effects.
Rotate by 90/180/270 degrees to adjust for mobile devices in portrait mode.
Optimized for SSSE3/AVX2 on x86/x64.
Optimized for Neon on Arm.
Optimized for MSA on Mips
2. 编译过程
当然你也可以放在Android Studio上编译。这里是脱离Android studio开发环境编译，直接编译好动静态库和头文件，可以copy给其它库用。
2.1 下载
下载源码
: https://chromium.googlesource.com/libyuv/libyuv/+archive/refs/heads/master.tar.gz
现在最新版本是 1917,可以在下载的源码中include/libyuv/version.h查看版本号
2.2 稍改CMakeLists.txt脚本
原本我们并不需要改变CMakeLists.txt脚本，只是为了存放目录，把动、静态库放在lib目录，头文件放在include目录。如果不改变脚本，编译后，自己手动copy也是可以的。
最重要的就是，Android studio集成cmake编译，是在打包的时候才strip掉符号表。我们脱离Android studio开发环境，直接使用Cmake编译，不管是Release版本还是Debug版本，Cmake都没有Strip掉符号表，库会比较大，所以我们在脚本里定制一个command，直接strip掉符号表。一般我们不会debug开源库
# CMakeLists for libyuv
# Originally created for "roxlu build system" to compile libyuv on windows
# Run with -DTEST=ON to build unit tests
PROJECT ( YUV C CXX ) # "C" is required even for C++ projects
CMAKE_MINIMUM_REQUIRED( VERSION 2.8 )
OPTION( TEST "Built unit tests" OFF )
SET ( ly_base_dir ${PROJECT_SOURCE_DIR} )
SET ( ly_src_dir ${ly_base_dir}/source )
SET ( ly_inc_dir ${ly_base_dir}/include )
SET ( ly_tst_dir ${ly_base_dir}/unit_test )
SET ( ly_lib_name yuv )
SET ( ly_lib_static ${ly_lib_name} )
SET ( ly_lib_shared ${ly_lib_name}_shared )
FILE ( GLOB_RECURSE ly_source_files ${ly_src_dir}/*.cc )
LIST ( SORT ly_source_files )
FILE ( GLOB_RECURSE ly_unittest_sources ${ly_tst_dir}/*.cc )
LIST ( SORT ly_unittest_sources )
INCLUDE_DIRECTORIES( BEFORE ${ly_inc_dir} )
# this creates the static library (.a)
ADD_LIBRARY ( ${ly_lib_static} STATIC ${ly_source_files} )
# this creates the shared library (.so)
ADD_LIBRARY ( ${ly_lib_shared} SHARED ${ly_source_files} )
SET_TARGET_PROPERTIES ( ${ly_lib_shared} PROPERTIES OUTPUT_NAME "${ly_lib_name}" )
SET_TARGET_PROPERTIES ( ${ly_lib_shared} PROPERTIES PREFIX "lib" )
# this creates the conversion tool
ADD_EXECUTABLE ( yuvconvert ${ly_base_dir}/util/yuvconvert.cc )
TARGET_LINK_LIBRARIES ( yuvconvert ${ly_lib_static} )
INCLUDE ( FindJPEG )
if (JPEG_FOUND)
include_directories( ${JPEG_INCLUDE_DIR} )
target_link_libraries( yuvconvert ${JPEG_LIBRARY} )
add_definitions( -DHAVE_JPEG )
endif()
if(TEST)
find_library(GTEST_LIBRARY gtest)
if(GTEST_LIBRARY STREQUAL "GTEST_LIBRARY-NOTFOUND")
set(GTEST_SRC_DIR /usr/src/gtest CACHE STRING "Location of gtest sources")
if(EXISTS ${GTEST_SRC_DIR}/src/gtest-all.cc)
message(STATUS "building gtest from sources in ${GTEST_SRC_DIR}")
set(gtest_sources ${GTEST_SRC_DIR}/src/gtest-all.cc)
add_library(gtest STATIC ${gtest_sources})
include_directories(${GTEST_SRC_DIR})
include_directories(${GTEST_SRC_DIR}/include)
set(GTEST_LIBRARY gtest)
else()
message(FATAL_ERROR "TEST is set but unable to find gtest library")
endif()
endif()
add_executable(libyuv_unittest ${ly_unittest_sources})
target_link_libraries(libyuv_unittest ${ly_lib_name} ${GTEST_LIBRARY})
find_library(PTHREAD_LIBRARY pthread)
if(NOT PTHREAD_LIBRARY STREQUAL "PTHREAD_LIBRARY-NOTFOUND")
target_link_libraries(libyuv_unittest pthread)
endif()
if (JPEG_FOUND)
target_link_libraries(libyuv_unittest ${JPEG_LIBRARY})
endif()
if(NACL AND NACL_LIBC STREQUAL "newlib")
target_link_libraries(libyuv_unittest glibc-compat)
endif()
find_library(GFLAGS_LIBRARY gflags)
if(NOT GFLAGS_LIBRARY STREQUAL "GFLAGS_LIBRARY-NOTFOUND")
target_link_libraries(libyuv_unittest gflags)
add_definitions(-DLIBYUV_USE_GFLAGS)
endif()
endif()
# ----------------------------------新加的内容-------------------------------------
# 为了是目录更明确，自己创建目录
if(NOT EXISTS CMAKE_INSTALL_PREFIX)
message(WARNING "目录${CMAKE_INSTALL_PREFIX}-----not exists---------------")
file(MAKE_DIRECTORY ${CMAKE_INSTALL_PREFIX}/bin ${CMAKE_INSTALL_PREFIX}/lib ${CMAKE_INSTALL_PREFIX}/include)
endif()
#copy头文件文件夹,动态库和静态库文件都放在lib目录,头文件放在include目录
add_custom_command( TARGET ${ly_lib_shared} POST_BUILD
COMMAND ${CMAKE_COMMAND} -E copy_directory ${ly_inc_dir} ${CMAKE_INSTALL_PREFIX}/include)
# strip动态库的符号表
add_custom_command( TARGET ${ly_lib_shared} POST_BUILD
COMMAND "${ANDROID_TOOLCHAIN_PREFIX}strip" "--strip-unneeded" "-o"
"${CMAKE_INSTALL_PREFIX}/lib/lib${ly_lib_name}-strip.so" "${CMAKE_INSTALL_PREFIX}/lib/lib${ly_lib_name}.so"
COMMENT "strip符号表")
# ---------------------------------------------------------------------------------
# install the conversion tool, .so, .a, and all the header files
INSTALL ( PROGRAMS ${CMAKE_BINARY_DIR}/yuvconvert DESTINATION ${CMAKE_INSTALL_PREFIX}/bin )
INSTALL ( TARGETS ${ly_lib_static} DESTINATION ${CMAKE_INSTALL_PREFIX}/lib )
INSTALL ( TARGETS ${ly_lib_shared} LIBRARY DESTINATION lib RUNTIME DESTINATION ${CMAKE_INSTALL_PREFIX}/bin )
INSTALL ( DIRECTORY ${PROJECT_SOURCE_DIR}/include/ DESTINATION ${CMAKE_INSTALL_PREFIX}/include )
# create the .deb and .rpm packages using cpack
INCLUDE ( CM_linux_packages.cmake )
2.3 Windows环境编译脚本bat
@echo off
cls
::==========================================================================
::本脚本用来用来在Windows环境使用Cmake交叉编译Android使用的libyuv库
::==========================================================================
title cmake build libyuv
chcp 65001>nul
echo.
echo.
echo.--------本脚本用来用来在Windows环境使用Cmake交叉编译Android使用的库------
echo.
echo CMD Path:%cd%
echo 当前 dir:%~dp0
rem 切换到当前目录
cd /d %~dp0
:: --------------------------------------------------------------------------
rem 临时变量
set ANDROID_NDK=F:/Android/android-ndk-r16b
set CMAKE_PATH=D:/Android/android-sdk/cmake/3.6.4111459
set NASM_PATH=D:/Progra~1/Android/nasm-2.13.03
set ANDROID_VERSION=24
set SOURCE_DIR=./libyuv-refs_heads_master
set NATIVE_BUILD_DIR=.
set INSTALL_DIR=%~dp0
:: --------------------------------------------------------------------------
echo.
echo.--------------------------开始build--------------------------------------
echo.
rem --make armeabi
call:buildLibTurboJpeg armeabi
rem --make armeabi-v7a
call:buildLibTurboJpeg armeabi-v7a
rem --make arm64-v8a
call:buildLibTurboJpeg arm64-v8a
rem --make x86
call:buildLibTurboJpeg x86
rem --make x86_64
call:buildLibTurboJpeg x86_64
set timeout=5
echo.倒计时 %timeout% 秒钟后自动退出
for /L %%a in (%timeout% -1 1) do ( ^
set /p=%%a . <nul&ping -n 2 127.0.0.1>nul
)
echo.
echo.&pause&goto:eof
:: --------------------------------------------------------------------------
rem 定义函数 (%1:arch,%2:abi)
:buildLibTurboJpeg
setlocal
echo.[func]-----------------start make [%1]---------------------------
echo.
set ABI=%1
set BINARY_DIR="%NATIVE_BUILD_DIR%/bin/%ABI%"
set PLATFORM_VERSION=%ANDROID_VERSION%
set LIB_OUTPUT_DIR="%INSTALL_DIR%/dist/%ABI%"
echo [func]----PLATFORM_VERSION==%ANDROID_VERSION%
echo [func]----ABI==%ABI%
echo [func]----SOURCE_DIR==%SOURCE_DIR%
echo [func]----BINARY_DIR==%BINARY_DIR%
echo [func]----LIB_OUTPUT_DIR==%LIB_OUTPUT_DIR%
echo.
echo.
if not exist %BINARY_DIR% md %BINARY_DIR%
cd /d %BINARY_DIR%
:: -DCMAKE_LIBRARY_OUTPUT_DIRECTORY=../../%LIB_OUTPUT_DIR% ^
:: -DCMAKE_ARCHIVE_OUTPUT_DIRECTORY=../../%LIB_OUTPUT_DIR% ^
::-DCMAKE_LIBRARY_OUTPUT_DIRECTORY=%LIB_OUTPUT_DIR% ^
::-DCMAKE_ARCHIVE_OUTPUT_DIRECTORY=%LIB_OUTPUT_DIR% ^
rem 开源库有提供cmake Android Gradle - Ninja ^
cmake ^
-DANDROID_ABI=%ABI% ^
-DANDROID_PLATFORM=android-%PLATFORM_VERSION% ^
-DCMAKE_INSTALL_PREFIX=%LIB_OUTPUT_DIR% ^
-DCMAKE_LIBRARY_OUTPUT_DIRECTORY=%LIB_OUTPUT_DIR%/lib ^
-DCMAKE_ARCHIVE_OUTPUT_DIRECTORY=%LIB_OUTPUT_DIR%/lib ^
-DCMAKE_BUILD_TYPE=Release ^
-DANDROID_NDK=%ANDROID_NDK% ^
-DCMAKE_TOOLCHAIN_FILE=%ANDROID_NDK%/build/cmake/android.toolchain.cmake ^
-DCMAKE_MAKE_PROGRAM=%CMAKE_PATH%/bin/ninja.exe ^
-G"Android Gradle - Ninja" ^
-DANDROID_ARM_NEON=TRUE ^
-DANDROID_TOOLCHAIN=clang ^
-DANDROID_STL=c++_static ^
-DCMAKE_C_FLAGS=" -Os -Wall -pipe -fPIC" ^
-DANDROID_CPP_FEATURES=rtti exceptions ^
../../%SOURCE_DIR%
cmake --build ./
rem ninja -C .
cd ../../
echo.[func]-----------------[%1] make end---------------------------
echo.
endlocal
goto:eof
2.4 编译静态、动态库
双击执行以上脚本保存的bat文件即可，等待编译完成
编译安装目录
ABIS
arm64-v8a
libs
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