Add convenient Stream::getDimensions method to extract video dimension.

src/FFMpeg/FFProbe/DataMapping/Stream.php

@@ -11,6 +11,10 @@
 
 namespace FFMpeg\FFProbe\DataMapping;
 
+use FFMpeg\Exception\LogicException;
+use FFMpeg\Exception\RuntimeException;
+use FFMpeg\Coordinate\Dimension;
+
 class Stream extends AbstractData
 {
     /**
@@ -32,4 +36,63 @@ class Stream extends AbstractData
     {
         return $this->has('codec_type') ? 'video' === $this->get('codec_type') : false;
     }
+
+    /**
+     * Returns the dimension of the video stream.
+     *
+     * @return Dimension
+     *
+     * @throws LogicException   In case the stream is not a video stream.
+     * @throws RuntimeException In case the dimensions can not be extracted.
+     */
+    public function getDimensions()
+    {
+        if (!$this->isVideo()) {
+            throw new LogicException('Dimensions can only be retrieved from video streams.');
+        }
+
+        $width = $height = $sampleRatio = $displayRatio = null;
+
+        if ($this->has('width')) {
+            $width = $this->get('width');
+        }
+        if ($this->has('height')) {
+            $height = $this->get('height');
+        }
+        if (null !== $ratio = $this->extractRatio($this, 'sample_aspect_ratio')) {
+            $sampleRatio = $ratio;
+        }
+        if (null !== $ratio = $this->extractRatio($this, 'display_aspect_ratio')) {
+            $displayRatio = $ratio;
+        }
+
+        if (null === $height || null === $width) {
+            throw new RuntimeException('Unable to extract dimensions.');
+        }
+
+        if (null !== $displayRatio && null !== $sampleRatio) {
+            $width = round($width / $sampleRatio[0] * $sampleRatio[1] * $displayRatio[0] / $displayRatio[1]);
+        }
+
+        return new Dimension($width, $height);
+    }
+
+    /**
+     * Extracts a ratio from a string in a \d+:\d+ format given a key name.
+     *
+     * @param  Stream     $stream The stream where to look for the ratio.
+     * @param  string     $name   the name of the key.
+     * @return null|array An array containing the width and the height, null if not found.
+     */
+    private function extractRatio(Stream $stream, $name)
+    {
+        if ($stream->has($name)) {
+            $ratio = $stream->get($name);
+            if (preg_match('/\d+:\d+/', $ratio)) {
+                return array_map(function ($int) { return (int) $int; }, explode(':', $ratio));
+            }
+        }
+
+        return null;
+    }
 }