libyuv库编译

下载源代码

执行以下命令下载libyuv源代码

git clone https://chromium.googlesource.com/libyuv/libyuv
# 或者使用以下镜像仓库(非官方)
git clone https://github.com.cnpmjs.org/lemenkov/libyuv.git
git clone https://hub.fastgit.org/lemenkov/libyuv.git
git clone git@git.zhlh6.cn:lemenkov/libyuv.git

编译

在 libyuv 工程根路径下 Android.mk 文件中添加如下配置

APP_ABI := armeabi-v7a 
APP_PLATFORM := android-14

使用如下命令进行编译

ndk-build \
    APP_BUILD_SCRIPT=Android.mk \
    NDK_PROJECT_PATH=. \
    APP_PLATFORM=android-21

出现以下错误

Android NDK: Module yuv depends on undefined modules: jpeg

百度一下，发现有人使用NDK-r10e版本编译可行，但是不想再下载旧版本NDK，所以决定直接把 libyuv 源码直接集成至工程中。

集成

将 libyuv 中的 include、source、CMakeLists.txt 目录全部拷贝至工程 cpp/third/libyuv路径下。注意 CMakeLists.txt 文件需要修改，具体如下 CMakeLists.txt 修改

工程主 CMakeLists.txt 需要新增如下内容

include_directories(${CMAKE_SOURCE_DIR}/third/libyuv/include)
add_subdirectory(${CMAKE_SOURCE_DIR}/third/libyuv)

target_link_libraries(
        YourProjectName
        ...
        # third library
        yuv
        )

测试

在你的代码中 #include <libyuv.h>，然后对工程进行build，编译通过则正常。

CMakeLists.txt 修改

# 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 ()


# install the conversion tool, .so, .a, and all the header files
#INSTALL(PROGRAMS ${CMAKE_BINARY_DIR}/yuvconvert DESTINATION bin)
#INSTALL(TARGETS ${ly_lib_static} DESTINATION lib)
#INSTALL(TARGETS ${ly_lib_shared} LIBRARY DESTINATION lib RUNTIME DESTINATION bin)
INSTALL(DIRECTORY ${PROJECT_SOURCE_DIR}/include/ DESTINATION include)

# create the .deb and .rpm packages using cpack
#INCLUDE(CM_linux_packages.cmake)

示例代码

MainActivit

    /**
     * show nv21 image
     */
    private void showNV21Image() {
        byte[] imageData = null;
        try {
            InputStream is = getAssets().open("image_w720_h1280.nv21");
            int size = is.available();
            imageData = new byte[size];
            is.read(imageData);
            is.close();
        } catch (Exception ex) {
            ex.printStackTrace();
        }

        if (imageData != null) {
            int width = 720;
            int height = 1280;
            int length = width * height * 3 / 2;
            byte[] i420Cache = new byte[length];

            {
                NativeImageUtils.nv21Transform(imageData, i420Cache, width, height, 270, true);

                bitmap = nv21ToBitmap.nv21ToBitmap(i420Cache, height, width);

                if (bitmap != null) {
                    Bitmap finalBitmap = bitmap;
                    runOnUiThread(() -> {
                        mBinding.imgContent.setImageBitmap(finalBitmap);
                    });
                }
            }
        }
    }

ImageUtils.cpp

jint nv21Transform(jBytePoint srcNv21Data, jBytePoint dstData, int width, int height, int rotate,
                   jboolean mirror) {
    jint length = width * height * 3 / 2;

    auto *i420Cache = new jbyte[length];

    // 将转换后的I420数据缓存在cacheData
    int ret = nv21ToI420(srcNv21Data, i420Cache, width, height);
    if (ret < 0) {
        delete[] i420Cache;
        return ret;
    }

    auto *i420TransformCache = new jbyte[length];
    ret = i420Transform(i420Cache, i420TransformCache, width, height, rotate, mirror);
    delete[] i420Cache;

    if (ret < 0) {
        delete[] i420TransformCache;
        return ret;
    }

    ret = i420ToNV21(i420TransformCache, dstData, width, height);
    delete[] i420TransformCache;
    return ret;
}

代码地址：ImageUtils