Non-laravel package class not found

I'm trying to use a non-laravel package added by composer to my project but no matter what I do, I get this message:

"Class 'Shaka\\Options\\Streams\\Stream' not found /home/server/Code/Project/app/Http/Controllers/General/FileController.php 61

I added the package to my Lumen project using composer like:

composer require aminyazdanpanah/php-shaka

Then I used it in my controller like:

use \Shaka\Options\Streams\Stream;

public function ShakaPlay()
{
    $stream1 = Stream::input(storage_path('app/media/3/123.mp4'));
    $stream1->streamSelector('video')->output('video.mp4');
}

But I get above error message, I checked the Stream class namespace it's :

namespace Shaka\Options\Streams;

Any suggestion?

via Chebli Mohamed