【昉·星光 2 高性能RISC-V单板计算机体验】三：基于RISC-V交叉编译工具链的OpenCV库编译

https://ffmpeg.org/releases/ffmpeg-snapshot.tar.bz2

前期准备

OpenCV库的交叉编译需要以下几个条件：

1. Ubuntu虚拟机
2. 已经编译好的riscv交叉编译工具链
3. OpenCV源码
4. OpenCV_contrib
5. 几个依赖库下载：zlib、libjpeg、libpng、ffmpeg

zlib的下载地址是：https://zlib.net/fossils/zlib-1.2.8.tar.gz

libjpeg的地址是：http://www.ijg.org/files/jpegsrc.v9e.tar.gz

libpng的下载地址：https://sourceforge.net/projects/libpng/files/libpng16/older-releases/1.6.18/libpng-1.6.18.tar.gz/download

x264的下载地址：https://download.videolan.org/x264/snapshots/x264-snapshot-20151030-2245-stable.tar.bz2

xvidcore的下载地址：http://downloads.xvid.org/downloads/xvidcore-1.3.3.tar.gz

yasm的下载地址：http://www.tortall.net/projects/yasm/releases/yasm-1.3.0.tar.gz

ffmpeg的下载地址：https://ffmpeg.org/releases/ffmpeg-snapshot.tar.bz2

首先进行依赖库进行逐个安装，运行命令如下：

export PATH=$PATH:/opt/riscv/bin

zlib：\./configure \-\-prefix=/home/linrui/Downloads/opencv\_sipeed/opencv\_depend –share
修改Makefile：

CC=riscv64\-unknown\-linux\-gnu\-gcc

AR=riscv64\-unknown\-linux\-gnu\-ar

RANLIB=riscv64\-unknown\-linux\-gnu\-ranlib

make & make install

LDSHARED=riscv64\-unknown\-linux\-gcc \-shared\-Wl,\-soname,libz\.so\.1,\-\-version\-script,zlib\.map

libjpeg：\./configure\-\-host=riscv64\-unknown\-linux\-gnu \-\-prefix=/home/linrui/Downloads/opencv\_sipeed/opencv\_depend \-\-enable\-shared \-\-enable\-static

make & make install

libpng：\./configure \-\-host=riscv64\-unknown\-linux\-gnu \-\-prefix=/home/linrui/Downloads/opencv\_sipeed/opencv\_depend \-\-enable\-shared \-\-enable\-static

make & make install

yasm：CC=riscv64\-unknown\-linux\-gnu\-gcc \./configure\-\-enable\-shared \-\-host=riscv64\-unknown\-linux\-gnu \-\-disable\-asm –prefix=/home/linrui/Downloads/opencv\_sipeed/opencv\_depend

make & make install

libx264：CC= riscv64\-unknown\-linux\-gnu\-gcc \./configure\-\-enable\-shared \-\-host=iscv64\-unknown\-linux\-gnu \-\-disable\-asm \-\-prefix=/home/linrui/Downloads/opencv\_sipeed/opencv\_depend

make & make install

libxvidcore：cd build/generic

\./configure \-\-prefix=/home/linrui/Downloads/opencv\_sipeed/opencv\_depend \-\-host= riscv64\-unknown\-linux\-gnu  \-\-disable\-assembly

make & make install

ffmpeg：\./configure \-\-prefix=/home/linrui/Downloads/opencv\_sipeed/opencv\_depend \-\-enable\-shared \-\-disable\-static \-\-enable\-gpl \-\-enable\-cross\-compile \-\-cross\-prefix=riscv64\-unknown\-linux\-gnu\- \-\-arch=riscv \-\-disable\-stripping \-\-target\-os=linux \-\-enable\-libxvid\-\-cc=riscv64\-unknown\-linux\-gnu\-gcc \-\-enable\-swscale \-\-extra\-ldflags=\-L/home/linrui/Downloads/opencv\_sipeed/opencv\_depend/lib \-\-extra\-cflags=\-I/home/linrui/Downloads/opencv\_sipeed/opencv\_depend/include

make & make install

OpenCV交叉编译

OpenCV的源码可以在OpenCV的官网进行下载，并且下载opencv_contrib。下载好后，编写toolchain.cmake文件如下：

\#\#\#\#\#\#\#\#\#\#\#user defined\#\#\#\#\#\#\#\#\#\#\#\#\#

set\( CMAKE\_SYSTEM\_NAME Linux \)

set\( CMAKE\_SYSTEM\_PROCESSOR riscv64 \)

set\( CMAKE\_C\_COMPILER riscv64\-unknown\-linux\-gnu\-gcc \)

set\( CMAKE\_CXX\_COMPILER riscv64\-unknown\-linux\-gnu\-g\+\+ \)

\#\#\#\#\#\#\#\#\#\#\#user defined\#\#\#\#\#\#\#\#\#\#\#\#\#

set\(CMAKE\_FIND\_ROOT\_PATH "~/Documents/opencv/opencv\-depend" \)

set\( CMAKE\_FIND\_ROOT\_PATH\_MODE\_PROGRAM NEVER \)

set\( CMAKE\_FIND\_ROOT\_PATH\_MODE\_LIBRARY ONLY\)

set\( CMAKE\_FIND\_ROOT\_PATH\_MODE\_INCLUDE ONLY\)

进入到OpenCV的源码文件夹下，运行命令：

mkdir build && cd build

cmake \-DCMAKE\_TOOLCHAIN\_FILE=toolchain\.cmake \.\.

在/opt/riscv/riscv64-unknown-linux-gnu/文件夹下创建ffmpeg-config.cmake文件，ffmpeg-config.cmake文件编写如下：

set\(ffmpeg\_path "$\{CMAKE\_CURRENT\_LIST\_DIR\}"\)

message\("ffmpeg\_path: $\{ffmpeg\_path\}"\)

set\(FFMPEG\_EXEC\_DIR "$\{ffmpeg\_path\}/bin"\)

set\(FFMPEG\_LIBDIR "$\{ffmpeg\_path\}/lib"\)

set\(FFMPEG\_INCLUDE\_DIRS "$\{ffmpeg\_path\}/include"\)

\# library names

set\(FFMPEG\_LIBRARIES

${FFMPEG_LIBDIR}/libavformat.dylib

${FFMPEG_LIBDIR}/libavdevice.dylib

${FFMPEG_LIBDIR}/libavcodec.dylib

${FFMPEG_LIBDIR}/libavutil.dylib

${FFMPEG_LIBDIR}/libswscale.dylib

${FFMPEG_LIBDIR}/libswresample.dylib

${FFMPEG_LIBDIR}/libavfilter.dylib

\)

\# found status

set\(FFMPEG\_libavformat\_FOUND TRUE\)

set\(FFMPEG\_libavdevice\_FOUND TRUE\)

set\(FFMPEG\_libavcodec\_FOUND TRUE\)

set\(FFMPEG\_libavutil\_FOUND TRUE\)

set\(FFMPEG\_libswscale\_FOUND TRUE\)

set\(FFMPEG\_libswresample\_FOUND TRUE\)

set\(FFMPEG\_libavfilter\_FOUND TRUE\)

set\(FFMPEG\_libavresample\_FOUND FALSE\) //ffmpeg高版本已经没有libavresample了

\# library versions, 注意这几个变量，一定要设置为全局CACHE变量

set\(FFMPEG\_libavutil\_VERSION 57\.36\.101 CACHE INTERNAL "FFMPEG\_libavutil\_VERSION"\) \# info

set\(FFMPEG\_libavcodec\_VERSION 59\.42\.104 CACHE INTERNAL "FFMPEG\_libavcodec\_VERSION"\) \# info

set\(FFMPEG\_libavformat\_VERSION 59\.30\.100 CACHE INTERNAL "FFMPEG\_libavformat\_VERSION"\) \# info

set\(FFMPEG\_libavdevice\_VERSION 59\.8\.101 CACHE INTERNAL "FFMPEG\_libavdevice\_VERSION"\) \# info

set\(FFMPEG\_libavfilter\_VERSION 8\.48\.100 CACHE INTERNAL "FFMPEG\_libavfilter\_VERSION"\) \# info

set\(FFMPEG\_libswscale\_VERSION 6\.8\.104 CACHE INTERNAL "FFMPEG\_libswscale\_VERSION"\) \# info

set\(FFMPEG\_libswresample\_VERSION 4\.9\.100 CACHE INTERNAL "FFMPEG\_libswresample\_VERSION"\) \# info

set\(FFMPEG\_FOUND TRUE\)

set\(FFMPEG\_LIBS $\{FFMPEG\_LIBRARIES\}\)

status\("    \#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\# FFMPEG:"       FFMPEG\_FOUND         THEN "YES \(find\_package\)"                       ELSE "NO \(find\_package\)"\)

status\("      avcodec:"      FFMPEG\_libavcodec\_VERSION    THEN "YES \($\{FFMPEG\_libavcodec\_VERSION\}\)"    ELSE NO\)

status\("      avformat:"     FFMPEG\_libavformat\_VERSION   THEN "YES \($\{FFMPEG\_libavformat\_VERSION\}\)"   ELSE NO\)

status\("      avutil:"       FFMPEG\_libavutil\_VERSION     THEN "YES \($\{FFMPEG\_libavutil\_VERSION\}\)"     ELSE NO\)

status\("      swscale:"      FFMPEG\_libswscale\_VERSION    THEN "YES \($\{FFMPEG\_libswscale\_VERSION\}\)"    ELSE NO\)

status\("      avresample:"   FFMPEG\_libavresample\_VERSION THEN "YES \($\{FFMPEG\_libavresample\_VERSION\}\)" ELSE NO\)