问用ffmpeg交叉编译OpenCV

EN

    sudo apt-get install libavcodec-dev:armhf libavformat-dev:armhf libswscale-dev:armhf
    sudo apt-get install libjpeg-dev:armhf libpng-dev:armhf libtiff-dev:armhf libjasper-dev:armhf

    cmake -DENABLE_NEON=ON -DENABLE_VFPV3=ON -DWITH_FFMPEG=ON  -DCMAKE_TOOLCHAIN_FILE=../opencv/platforms/linux/arm-gnueabi.toolchain.cmake ../opencv

    set(GCC_COMPILER_VERSION "" CACHE STRING "GCC Compiler version")
    set(GNU_MACHINE "arm-linux-gnueabi" CACHE STRING "GNU compiler triple")
    include("${CMAKE_CURRENT_LIST_DIR}/arm.toolchain.cmake")

if(COMMAND toolchain_save_config)
  return() # prevent recursive call
endif()

set(CMAKE_SYSTEM_NAME Linux)
set(CMAKE_SYSTEM_VERSION 1)
if(NOT DEFINED CMAKE_SYSTEM_PROCESSOR)
  set(CMAKE_SYSTEM_PROCESSOR arm)
else()
  #message("CMAKE_SYSTEM_PROCESSOR=${CMAKE_SYSTEM_PROCESSOR}")
endif()

include("${CMAKE_CURRENT_LIST_DIR}/gnu.toolchain.cmake")

if(CMAKE_SYSTEM_PROCESSOR STREQUAL arm AND NOT ARM_IGNORE_FP)
  set(FLOAT_ABI_SUFFIX "")
  if(NOT SOFTFP)
    set(FLOAT_ABI_SUFFIX "hf")
  endif()
endif()

if(NOT "x${GCC_COMPILER_VERSION}" STREQUAL "x")
  set(__GCC_VER_SUFFIX "-${GCC_COMPILER_VERSION}")
endif()

if(NOT DEFINED CMAKE_C_COMPILER)
  find_program(CMAKE_C_COMPILER NAMES ${GNU_MACHINE}${FLOAT_ABI_SUFFIX}-gcc${__GCC_VER_SUFFIX})
else()
  #message(WARNING "CMAKE_C_COMPILER=${CMAKE_C_COMPILER} is defined")
endif()
if(NOT DEFINED CMAKE_CXX_COMPILER)
  find_program(CMAKE_CXX_COMPILER NAMES ${GNU_MACHINE}${FLOAT_ABI_SUFFIX}-g++${__GCC_VER_SUFFIX})
else()
  #message(WARNING "CMAKE_CXX_COMPILER=${CMAKE_CXX_COMPILER} is defined")
endif()
if(NOT DEFINED CMAKE_LINKER)
  find_program(CMAKE_LINKER NAMES ${GNU_MACHINE}${FLOAT_ABI_SUFFIX}-ld${__GCC_VER_SUFFIX} ${GNU_MACHINE}${FLOAT_ABI_SUFFIX}-ld)
else()
  #message(WARNING "CMAKE_LINKER=${CMAKE_LINKER} is defined")
endif()
if(NOT DEFINED CMAKE_AR)
  find_program(CMAKE_AR NAMES ${GNU_MACHINE}${FLOAT_ABI_SUFFIX}-ar${__GCC_VER_SUFFIX} ${GNU_MACHINE}${FLOAT_ABI_SUFFIX}-ar)
else()
  #message(WARNING "CMAKE_AR=${CMAKE_AR} is defined")
endif()

if(NOT DEFINED ARM_LINUX_SYSROOT AND DEFINED GNU_MACHINE)
  set(ARM_LINUX_SYSROOT /usr/lib/${GNU_MACHINE}${FLOAT_ABI_SUFFIX})
endif()

if(NOT DEFINED CMAKE_CXX_FLAGS)
  set(CMAKE_CXX_FLAGS           "" CACHE INTERAL "")
  set(CMAKE_C_FLAGS             "" CACHE INTERAL "")
  set(CMAKE_SHARED_LINKER_FLAGS "" CACHE INTERAL "")
  set(CMAKE_MODULE_LINKER_FLAGS "" CACHE INTERAL "")
  set(CMAKE_EXE_LINKER_FLAGS    "" CACHE INTERAL "")

  set(CMAKE_CXX_FLAGS           "${CMAKE_CXX_FLAGS} -fdata-sections -Wa,--noexecstack -fsigned-char -Wno-psabi")
  set(CMAKE_C_FLAGS             "${CMAKE_C_FLAGS} -fdata-sections -Wa,--noexecstack -fsigned-char -Wno-psabi")
  if(CMAKE_SYSTEM_PROCESSOR STREQUAL arm)
    set(CMAKE_CXX_FLAGS           "-mthumb ${CMAKE_CXX_FLAGS}")
    set(CMAKE_C_FLAGS             "-mthumb ${CMAKE_C_FLAGS}")
    set(CMAKE_EXE_LINKER_FLAGS    "${CMAKE_EXE_LINKER_FLAGS} -Wl,-z,nocopyreloc")
  endif()
  if(CMAKE_SYSTEM_PROCESSOR STREQUAL arm)
    set(ARM_LINKER_FLAGS "-Wl,--fix-cortex-a8 -Wl,--no-undefined -Wl,--gc-sections -Wl,-z,noexecstack -Wl,-z,relro -Wl,-z,now")
  elseif(CMAKE_SYSTEM_PROCESSOR STREQUAL aarch64)
    set(ARM_LINKER_FLAGS "-Wl,--no-undefined -Wl,--gc-sections -Wl,-z,noexecstack -Wl,-z,relro -Wl,-z,now")
  endif()
  set(CMAKE_SHARED_LINKER_FLAGS "${ARM_LINKER_FLAGS} ${CMAKE_SHARED_LINKER_FLAGS}")
  set(CMAKE_MODULE_LINKER_FLAGS "${ARM_LINKER_FLAGS} ${CMAKE_MODULE_LINKER_FLAGS}")
  set(CMAKE_EXE_LINKER_FLAGS    "${ARM_LINKER_FLAGS} ${CMAKE_EXE_LINKER_FLAGS}")
else()
  #message(WARNING "CMAKE_CXX_FLAGS='${CMAKE_CXX_FLAGS}' is defined")
endif()

if(USE_NEON)
  message(WARNING "You use obsolete variable USE_NEON to enable NEON instruction set. Use -DENABLE_NEON=ON instead." )
  set(ENABLE_NEON TRUE)
elseif(USE_VFPV3)
  message(WARNING "You use obsolete variable USE_VFPV3 to enable VFPV3 instruction set. Use -DENABLE_VFPV3=ON instead." )
  set(ENABLE_VFPV3 TRUE)
endif()

set(CMAKE_FIND_ROOT_PATH ${CMAKE_FIND_ROOT_PATH} ${ARM_LINUX_SYSROOT})

    if(EXISTS ${CUDA_TOOLKIT_ROOT_DIR})
      set(CMAKE_FIND_ROOT_PATH ${CMAKE_FIND_ROOT_PATH} ${CUDA_TOOLKIT_ROOT_DIR})
    endif()

    set(TOOLCHAIN_CONFIG_VARS ${TOOLCHAIN_CONFIG_VARS}
        ARM_LINUX_SYSROOT
        ENABLE_NEON
        ENABLE_VFPV3
        CUDA_TOOLKIT_ROOT_DIR
    )
    toolchain_save_config()