title: how to include OpenCV's cv::VideoWriter when using vcpkg?
body: <p>I'm using vcpkg to install OpenCV4 on Windows.  But when I try to link my application, one of the OpenCV classes I'm using is giving me trouble:</p>
  <pre><code>2&gt;main.obj : error LNK2019: unresolved external symbol &quot;public: __cdecl cv::VideoWriter::VideoWriter(void)&quot; (??0VideoWriter@cv@@QEAA@XZ) referenced in function main
  2&gt;main.obj : error LNK2019: unresolved external symbol &quot;public: virtual __cdecl cv::VideoWriter::~VideoWriter(void)&quot; (??1VideoWriter@cv@@UEAA@XZ) referenced in function main
  2&gt;main.obj : error LNK2019: unresolved external symbol &quot;public: virtual bool __cdecl cv::VideoWriter::open(class std::basic_string&lt;char,struct std::char_traits&lt;char&gt;,class std::allocator&lt;char&gt; &gt; const &amp;,int,double,class cv::Size_&lt;int&gt;,bool)&quot; (?open@VideoWriter@cv@@UEAA_NAEBV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@HNV?$Size_@H@2@_N@Z) referenced in function main
  </code></pre>
  <p>So I'm thinking I need to enable a non-default feature.  OpenCV was originally installed like this:</p>
  <pre><code>vcpkg install --triplet x64-windows-static-md opencv4
  </code></pre>
  <p>By default, this seems to install <code>[dnn,jpeg,opengl,png,tiff,webp]</code>.</p>
  <p>I've also tried adding a few more of the optional features, including:</p>
  <pre><code>vcpkg install --triplet x64-windows-static-md opencv4[core,jpeg,opengl,png,tiff,webp,ffmpeg,openmp]
  </code></pre>
  <p>Output:</p>
  <pre><code>...cut...
  The package opencv4:x64-windows-static-md provides CMake targets:
  
  find_package(OpenCV CONFIG REQUIRED)
  # Note: 14 target(s) were omitted.
  target_link_libraries(main PRIVATE quirc opencv_ml libprotobuf opencv_core)
  </code></pre>
  <p>I'm using the vcpkg toolchain file when calling cmake to create the project.  And the relevant portion of my <code>CMakeLists.txt</code> file contains the following as instructed by vcpkg:</p>
  <pre><code>FIND_PACKAGE(OpenCV CONFIG REQUIRED)
  INCLUDE_DIRECTORIES ( BEFORE ${OpenCV_INCLUDE_DIRS} )
  ADD_EXECUTABLE ( mytest main.cpp )
  TARGET_LINK_LIBRARIES ( mytest PRIVATE quirc opencv_ml libprotobuf opencv_core )
  </code></pre>
  <p>Part of the problem is the vcpkg <code>ports/opencv4/control</code> file contains probably 20 optional features, and the descriptions are nearly useless.</p>
  <p><strong>My question:</strong></p>
  <p>Anyone know what vcpkg feature is needed to get access to the <code>cv::VideoWriter</code> class, or what to look for in the code so I can figure out which optional feature is required?</p>