Update of the README

README.md

@@ -227,6 +227,22 @@ The resize filter takes three parameters :
 - `$mode`, one of the constants `FFMpeg\Filters\Video\ResizeFilter::RESIZEMODE_*` constants
 - `$useStandards`, a boolean to force the use of the nearest aspect ratio standard.
 
+If you want a video in a non-standard ratio, you can use the padding filter to resize your video in the desired size, and wrap it into black bars.
+
+```php
+$video->filters()->pad($dimension);
+```
+
+The pad filter takes one parameter:
+
+- `$dimension`, an instance of `FFMpeg\Coordinate\Dimension`
+
+Don't forget to save it afterwards.
+
+```php
+$video->save(new FFMpeg\Format\Video\X264(), $new_file);
+```
+
 ###### Watermark
 
 Watermark a video with a given image.