如何爲Android平臺編譯 opencv3 和 opencv_contrib (Linux)

編譯出來的opencv庫有問題，正在調試中 ......

 

本文以編譯opencv 3.3.0 和 opencv_contrib 3.3.0爲例，系統爲 Linux x64 (Fedora 21)，具體步驟以下：

1. 下載 Source code zip 壓縮包

從下面網址，選擇 opencv 3.3.0 Source code 下載
https://github.com/opencv/opencv/releases

從下面網址，選擇下載與 opencv 3.3.0 對應的 opencv_contrib 3.3.0
https://github.com/opencv/opencv_contrib/releases

注意：opencv和opencv_contrib 版本必須保持一致，不然可能會出現編譯錯誤。

 

2. 下載 build-opencv-for-android 開源代碼

$ cd /mnt/work $ git clone https://github.com/tzutalin/build-opencv-for-android.git
$ cd build-opencv-for-android

 

3. 解壓源碼包並重命名

將opencv-3.3.0.zip 和 opencv_contrib-3.3.0.zip 都解壓到下載的build-opencv-for-android 開源代碼 所在目錄 /mnt/work/build-opencv-for-android 。

$ unzip opencv-3.3.0.zip -d /mnt/work/build-opencv-for-android $ unzip opencv_contrib-3.3.0.zip -d /mnt/work/build-opencv-for-android $ cd /mnt/work/build-opencv-for-android $ mv opencv-3.3.0 opencv $ mv opencv_contrib-3.3.0 opencv_contrib

 

4. 修改 build-opencv-for-android 開源代碼中 build-android-opencv.sh

修改內容以下：

修改 第 6 行代碼：

declare -a ANDROID_ABI_LIST=("x86" "x86_64" "armeabi" "arm64-v8a" "armeabi-v7a" "mips" "mips64")

爲

declare -a ANDROID_ABI_LIST=("armeabi-v7a")

最終代碼，以下：

 1 #!/bin/bash  2 NDK_ROOT="${1:-${NDK_ROOT}}"
 3 
 4 ### ABIs setup  5 #declare -a ANDROID_ABI_LIST=("x86" "x86_64" "armeabi-v7a with NEON" "arm64-v8a")
 6 declare -a ANDROID_ABI_LIST=("armeabi-v7a")
 7 
 8 ### path setup  9 SCRIPT=$(readlink -f $0)
10 WD=`dirname $SCRIPT` 11 OPENCV_ROOT="${WD}/opencv"
12 N_JOBS=${N_JOBS:-4} 13 
14 ### Download android-cmake 15 if [ ! -d "${WD}/android-cmake" ]; then
16     echo 'Cloning android-cmake' 17     git clone https://github.com/taka-no-me/android-cmake.git 18 fi 19 
20 INSTALL_DIR="${WD}/android_opencv"
21 rm -rf "${INSTALL_DIR}/opencv"
22 
23 ### Make each ABI target iteratly and sequentially 24 for i in "${ANDROID_ABI_LIST[@]}"
25 do
26     ANDROID_ABI="${i}"
27     echo "Start building ${ANDROID_ABI} version"
28 
29     if [ "${ANDROID_ABI}" = "armeabi" ]; then
30         API_LEVEL=19
31     else
32         API_LEVEL=21
33  fi 34 
35     temp_build_dir="${OPENCV_ROOT}/platforms/build_android_${ANDROID_ABI}"
36     ### Remove the build folder first, and create it 37     rm -rf "${temp_build_dir}"
38     mkdir -p "${temp_build_dir}"
39     cd "${temp_build_dir}"
40 
41     cmake -DCMAKE_BUILD_WITH_INSTALL_RPATH=ON \
42           -DCMAKE_TOOLCHAIN_FILE="${WD}/android-cmake/android.toolchain.cmake" \
43           -DANDROID_NDK="${NDK_ROOT}" \
44           -DANDROID_NATIVE_API_LEVEL=${API_LEVEL} \
45           -DANDROID_ABI="${ANDROID_ABI}" \
46           -D WITH_CUDA=OFF \
47           -D WITH_MATLAB=OFF \
48           -D BUILD_ANDROID_EXAMPLES=OFF \
49           -D BUILD_DOCS=OFF \
50           -D BUILD_PERF_TESTS=OFF \
51           -D BUILD_TESTS=OFF \
52           -DOPENCV_EXTRA_MODULES_PATH="${WD}/opencv_contrib/modules/"  \
53           -DCMAKE_INSTALL_PREFIX="${INSTALL_DIR}/opencv" \
54           ../..
55     # Build it 56     make -j${N_JOBS} 57     # Install it 58     make install/strip 59     ### Remove temp build folder 60     cd "${WD}"
61     rm -rf "${temp_build_dir}"
62     echo "end building ${ANDROID_ABI} version"
63 done

View Code

說明：

1). 因爲目前 大多數 android 平臺使用arm cpu, 採用armeabi-v7 指令集，爲了減小編譯時間，全部我只保留 "armeabi-v7a" ， 其餘刪除，若是須要也可保留。
2). armeabi-v7 表明 arm EABI version 7 指令集, EABI 爲 嵌入應用二進制接口 (Embedded Application Binary Interface) 。

 

5. 執行腳本 build-android-opencv.sh

$ ./build-android-opencv.sh /mnt/work/android/android-sdk-linux/ndk-bundle

注：build-android-opencv.sh腳本的通用的執行命令格式爲「./build-android-opencv.sh [NDK_ROOT]」，其中，參數NDK_ROOT是可選的，表示Android Native Development Kit (NDK) 頂層目錄，若是沒有提供，則會試圖尋找環境變量 ANDROID_NDK。

 

6. 查看編譯結果

編譯成功後，會在 build-opencv-for-android 目錄，即build-android-opencv.sh腳本所在目錄，生成 android_opencv目錄，其目錄結構以下：

$ tree -d android_opencv android_opencv └── opencv ├── apk └── sdk ├── etc │ ├── haarcascades │ └── lbpcascades └── native ├── 3rdparty │ └── libs │ └── armeabi-v7a ├── jni │ ├── abi-armeabi-v7a │ └── include │ ├── opencv │ └── opencv2 │ ├── aruco │ ├── bioinspired │ ├── calib3d │ ├── ccalib │ ├── core │ │ ├── cuda │ │ │ └── detail │ │ ├── hal │ │ └── utils │ ├── datasets │ ├── dnn │ ├── face │ ├── features2d │ ├── flann │ ├── fuzzy │ ├── highgui │ ├── imgcodecs │ ├── img_hash │ ├── imgproc │ │ ├── detail │ │ └── hal │ ├── line_descriptor │ ├── ml │ ├── objdetect │ ├── optflow │ ├── phase_unwrapping │ ├── photo │ ├── reg │ ├── rgbd │ ├── saliency │ ├── shape │ ├── stereo │ ├── stitching │ │ └── detail │ ├── structured_light │ ├── superres │ ├── surface_matching │ ├── text │ ├── tracking │ ├── video │ ├── videoio │ ├── videostab │ ├── xfeatures2d │ ├── ximgproc │ └── xphoto └── libs └── armeabi-v7a 62 directories

 

問題與解決方法

問題一

$ ./build-android-opencv.sh Start building armeabi-v7a version CMake Error at /mnt/work/video/res/opencv/build-opencv-for-android-master/android-cmake/android.toolchain.cmake:446 (message): Could not find neither Android NDK nor Android standalone toolchain. You should either set an environment variable: export ANDROID_NDK=~/my-android-ndk or export ANDROID_STANDALONE_TOOLCHAIN=~/my-android-toolchain or put the toolchain or NDK in the default path: sudo ln -s ~/my-android-ndk /opt/android-ndk sudo ln -s ~/my-android-toolchain /opt/android-toolchain Call Stack (most recent call first): /usr/share/cmake/Modules/CMakeDetermineSystem.cmake:98 (include) CMakeLists.txt:127 (project) CMake Error: Error required internal CMake variable not set, cmake may be not be built correctly. Missing variable is: CMAKE_CXX_COMPILER_ENV_VAR CMake Error: Error required internal CMake variable not set, cmake may be not be built correctly. Missing variable is: CMAKE_CXX_COMPILER CMake Error: Could not find cmake module file: /mnt/work/video/res/opencv/build-opencv-for-android-master/opencv/platforms/build_android_armeabi-v7a/CMakeFiles/3.0.2/CMakeCXXCompiler.cmake CMake Error: Error required internal CMake variable not set, cmake may be not be built correctly. Missing variable is: CMAKE_C_COMPILER_ENV_VAR CMake Error: Error required internal CMake variable not set, cmake may be not be built correctly. Missing variable is: CMAKE_C_COMPILER CMake Error: Could not find cmake module file: /mnt/work/video/res/opencv/build-opencv-for-android-master/opencv/platforms/build_android_armeabi-v7a/CMakeFiles/3.0.2/CMakeCCompiler.cmake CMake Error at CMakeLists.txt:127 (project): No CMAKE_CXX_COMPILER could be found. Tell CMake where to find the compiler by setting the CMake cache entry CMAKE_CXX_COMPILER to the full path to the compiler, or to the compiler name if it is in the PATH. CMake Error at CMakeLists.txt:127 (project): No CMAKE_C_COMPILER could be found. Tell CMake where to find the compiler by setting the CMake cache entry CMAKE_C_COMPILER to the full path to the compiler, or to the compiler name if it is in the PATH. CMake Error: CMAKE_CXX_COMPILER not set, after EnableLanguage CMake Error: CMAKE_C_COMPILER not set, after EnableLanguage -- Configuring incomplete, errors occurred!
make: *** No targets specified and no makefile found. Stop. make: *** No rule to make target 'install/strip'. Stop. end building armeabi-v7a version 

解決方法

方法一（推薦方法）

從命令行傳入 NDK_ROOT 目錄，以下：

$ ./build-android-opencv.sh /mnt/work/android/android-sdk-linux/ndk-bundle/

方法二，

根據提示，設置環境變量 ANDROID_NDK，以下

$ export ANDROID_NDK=/mnt/work/android/android-sdk-linux/ndk-bundle/ $ env | grep ANDROID_NDK ANDROID_NDK=/mnt/work/android/android-sdk-linux/ndk-bundle/ $ ./build-android-opencv.sh

 

參考資料

[1] Build and install OpenCV and contrib lib on Ubuntu / Android    連接一  連接二（轉載）

[2]  如何編譯 opencv3 和 opencv_contrib（Linux）