在自己編譯OpenCV時，因為種種原因可能會導致FFmpeg或ippicv下載不成功的問題，可以通過手動配置來解決這類問題，當然也可以直接配置之後再編譯。

在進行配置之前，首先前往GitHub下載相應的庫。

連結開啟之後頁面內容大致如上圖所示，圖中圈出了ffmpeg和iipicv的不同版本，具體用哪一版就各取所需吧。明確版本之後點選相應的連結進入下載。

下載完成之後解壓，位置不重要。

到此，準備完畢。

FFmpeg的配置

1. 將“..\opencv_3rdparty-ffmpeg-master_20160715\ffmpeg” 目錄中的 ffmpeg_version.cmake

   、opencv_ffmpeg.dll、opencv_ffmpeg_64.dll 三項複製到 “path to your OpenCV\opencv\sources\3rdparty\ffmpeg” 目錄下。
   
   將上圖中的三項複製到下圖的目錄中
   

2. 編輯 ffmpeg.cmake
   在 “path to your OpenCV\opencv\sources\3rdparty\ffmpeg” 中開啟檔案 ffmpeg.cmake ，將其內容修改為：

   message(STATUS "FFMPEG: Package successfully downloaded")
   include(${CMAKE_CURRENT_LIST_DIR}
    
   /ffmpeg_version.cmake)

   儲存內容。

到此，ffmpeg配置完畢。

ippicv的配置

1. 在前面下載解壓的目錄“..\opencv_3rdparty-ippicv-master_20151201\ippicv” 中將ippicv_windows_20151201.zip 解壓到當前目錄。
   
   在 “path to your OpenCV \opencv\sources\3rdparty\ippicv” 中建立資料夾unpack，將解壓得到的ippicv_win 複製到新建立的unpack 中。
   

2. 編輯 downloader.cmake
   將downloader.cmake

   的內容修改為：

#
# The script downloads ICV package
#
# On return this will define:
# OPENCV_ICV_PATH - path to unpacked downloaded package
#

function(_icv_downloader)
  # Commit SHA in the opencv_3rdparty repo
  set(IPPICV_BINARIES_COMMIT "81a676001ca8075ada498583e4166079e5744668")
  # Define actual ICV versions
  if(APPLE)
    set(OPENCV_ICV_PACKAGE_NAME "ippicv_macosx_20151201.tgz")
    set(OPENCV_ICV_PACKAGE_HASH "4ff1fde9a7cfdfe7250bfcd8334e0f2f")
    set(OPENCV_ICV_PLATFORM "macosx")
    set(OPENCV_ICV_PACKAGE_SUBDIR "/ippicv_osx")
  elseif(UNIX)
    if(ANDROID AND NOT (ANDROID_ABI STREQUAL x86 OR ANDROID_ABI STREQUAL x86_64))
      return()
    endif()
    set(OPENCV_ICV_PACKAGE_NAME "ippicv_linux_20151201.tgz")
    set(OPENCV_ICV_PACKAGE_HASH "808b791a6eac9ed78d32a7666804320e")
    set(OPENCV_ICV_PLATFORM "linux")
    set(OPENCV_ICV_PACKAGE_SUBDIR "/ippicv_lnx")
  elseif(WIN32 AND NOT ARM)
    set(OPENCV_ICV_PACKAGE_NAME "ippicv_windows_20151201.zip")
    set(OPENCV_ICV_PACKAGE_HASH "04e81ce5d0e329c3fbc606ae32cad44d")
    set(OPENCV_ICV_PLATFORM "windows")
    set(OPENCV_ICV_PACKAGE_SUBDIR "/ippicv_win")
  else()
    return() # Not supported
  endif()

  set(OPENCV_ICV_UNPACK_PATH "${CMAKE_CURRENT_LIST_DIR}/unpack")
  set(OPENCV_ICV_PATH "${OPENCV_ICV_UNPACK_PATH}${OPENCV_ICV_PACKAGE_SUBDIR}")

  message(STATUS "ICV: Package successfully downloaded")
  set(OPENCV_ICV_PATH "${OPENCV_ICV_PATH}" PARENT_SCOPE)
endfunction()

_icv_downloader()

儲存內容。
到此，ippicv配置完畢。

開始快樂的編譯OpenCV吧！