title: Darknet demo needs opencv for webcam images OpenCV=1
body: <p>I have been doing object detection with Yolo with the darknet git repository and wanted to start with video, I instaled OpenCV and try to run darknet for videos as:</p>
  
  <pre><code>$ ./darknet detector demo cfg/coco.data cfg/yolov3.cfg yolov3.weights &lt;video file&gt;
  </code></pre>
  
  <p>but I have the following message:</p>
  
  <pre><code>$ demo needs opencv for webcam images
  </code></pre>
  
  <p>I changed the second line in the makefile to:</p>
  
  <pre><code> OpenCV=1
  </code></pre>
  
  <p>but the message continue showing, and in the forums only. I followed a tutorial (<a href="https://pjreddie.com/darknet/install/#cuda" rel="nofollow noreferrer">https://pjreddie.com/darknet/install/#cuda</a>), but I do not not what re-make the project is and the test at the end shows that it is not compiling with opencv. I tried to remake it with:</p>
  
  <pre><code>remake darknet
  </code></pre>
  
  <p>but I have the following error with the libraries:</p>
  
  <pre><code>include/darknet.h:11:30: fatal error: cuda_runtime.h: No such file or directory
  compilation terminated.
  </code></pre>
  
  <p>Edit: I think is the instalation of CUDA as the comand nvidia-smi does not anything</p>