Add FFProbe#isValid

fixes #394

src/FFMpeg/FFProbe.php

@@ -170,6 +170,25 @@ class FFProbe
         return $this->probe($pathfile, '-show_format', static::TYPE_FORMAT);
     }
 
+    /**
+     * @api
+     *
+     * Checks wether the given `$pathfile` is considered a valid media file.
+     *
+     * @param string $pathfile
+     * @return bool
+     * @since 0.10.0
+     */
+    public function isValid(string $pathfile)
+    {
+        try {
+            return $this->format($pathfile)->get('duration') > 0;
+        } catch(\Exception $e) {
+            // complete invalid data
+            return false;
+        }
+    }
+
     /**
      * @api
      *