
      <tr><th>source</th><th>Object</th><th>source rectangle of video. </th></tr>
      <tr><th>source.x</th><th>Number</th><th>The x coordinate of the upper-left corner of the rectangle. </th></tr>
      <tr class="odd"><th>source.y</th><th>Number</th><th>The y coordinate of the upper-left corner of the rectangle. </th></tr>
      <tr><th>source.width</th><th>Number</th><th>The width of the rectangle. </th></tr>
      <tr class="odd"><th>source.height</th><th>Number</th><th>The height of the rectangle. </