IMX8MINI
linux
編譯組件 FFMPEG：
root@imx8mmevk:/bin# ffmpeg --version
ffmpeg version N-97346-g07ecc46 Copyright (c) 2000-2020 the FFmpeg developers
built with gcc 7.3.1 (Linaro GCC 7.3-2018.05) 20180425 [linaro-7.3-2018.05 revision d29120a424ecfbc167ef90065c0eeb7f91977701]
configuration: --prefix=/opt/ffmpeg --arch=arm64 --target-os=linux --enable-shared --cross-prefix=aarch64-linux-gnu-
libavutil 56. 42.102 / 56. 42.102
libavcodec 58. 78.102 / 58. 78.102
libavformat 58. 42.100 / 58. 42.100
libavdevice 58. 9.103 / 58. 9.103
libavfilter 7. 77.101 / 7. 77.101
libswscale 5. 6.101 / 5. 6.101
libswresample 3. 6.100 / 3. 6.100
Unrecognized option '-version'.
Error splitting the argument list: Option not found
由於使用aarch64-linux-gnu-gcc工具，編譯總是報：
aarch64-poky-linux-gcc is unable to create an executable file.
更換了工具gcc就編譯通過
root@sunday:~/ffmpeg/imx_ffmpeg# make install
編譯opencv：
說明原系統裏已有了，是4.0的版本，只是沒有注意到，又重新編譯了
中間遇到問題：
[ 45%] Linking CXX executable ../../bin/opencv_test_core
../../lib/libopencv_imgcodecs.so.4.3.0: undefined reference to `png_do_expand_palette_rgb8_neon'
../../lib/libopencv_imgcodecs.so.4.3.0: undefined reference to `png_init_filter_functions_neon'
../../lib/libopencv_imgcodecs.so.4.3.0: undefined reference to `png_do_expand_palette_rgba8_neon'
../../lib/libopencv_imgcodecs.so.4.3.0: undefined reference to `png_riffle_palette_neon'
collect2: error: ld returned 1 exit status
modules/core/CMakeFiles/opencv_test_core.dir/build.make:958: recipe for target 'bin/opencv_test_core' failed
make[2]: *** [bin/opencv_test_core] Error 1
CMakeFiles/Makefile2:1309: recipe for target 'modules/core/CMakeFiles/opencv_test_core.dir/all' failed
make[1]: *** [modules/core/CMakeFiles/opencv_test_core.dir/all] Error 2
Makefile:160: recipe for target 'all' failed
make: *** [all] Error 2
解決方式：
${HOME}/opencv-3.3.1/3rdparty/libpng/pngpriv.h
/*# if (defined(__ARM_NEON__) || defined(__ARM_NEON)) && \ */
# if defined(PNG_ARM_NEON) && (defined(ARM_NEON) || defined(__ARM_NEON)) && \
defined(PNG_ALIGNED_MEMORY_SUPPORTED)
# define PNG_ARM_NEON_OPT 2
# else
# define PNG_ARM_NEON_OPT 0
# endif
#endif