title: What is plane in a CVPixelbuffer?
body: <p>In <code>CVPixelBuffer</code> object, have one or many planes. (<a href="https://developer.apple.com/reference/corevideo/1665102-cvpixelbuffer" rel="nofollow noreferrer">reference</a>)
  We have methods to get number, heigh, the base address of plane.</p>
  <p>So what exactly the plane is? And how it constructed inside a <code>CVPixelBuffer</code>?</p>
  <p>Sample:</p>
  <pre><code>&lt;CVPixelBuffer 0x1465f8b30 width=1280 height=720 pixelFormat=420v iosurface=0x14a000008 planes=2&gt;
      &lt;Plane 0 width=1280 height=720 bytesPerRow=1280&gt;
      &lt;Plane 1 width=640 height=360 bytesPerRow=1280&gt;
  </code></pre>