add crop filter

src/FFMpeg/Filters/Video/CropFilter.php

@@ -0,0 +1,53 @@
+<?php
+/*
+ * This file is part of PHP-FFmpeg.
+ *
+ * (c) Alchemy <dev.team@alchemy.fr>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace FFMpeg\Filters\Video;
+
+use FFMpeg\Coordinate\Dimension;
+use FFMpeg\Coordinate\Point;
+use FFMpeg\Format\VideoInterface;
+use FFMpeg\Media\Video;
+
+class CropFilter implements VideoFilterInterface
+{
+    /** @var integer */
+    protected $priority;
+    /** @var Dimension */
+    protected $dimension;
+    /** @var Point */
+    protected $point;
+
+    public function __construct(Point $point, Dimension $dimension, $priority = 0)
+    {
+        $this->priority = $priority;
+        $this->dimension = $dimension;
+        $this->point = $point;
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function getPriority()
+    {
+        return $this->priority;
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function apply(Video $video, VideoInterface $format)
+    {
+        return array(
+            '-filter:v',
+            'crop=' .
+            $this->dimension->getWidth() .':' . $this->dimension->getHeight() . ':' . $this->point->getX() . ':' . $this->point->getY()
+        );
+    }
+}