Could not get filename correct on s3 export

[mhaisumali]

I am trying to get video from s3 URL and creating a thumbnail from the video all things are working fine but I am not able to retrieve the file real name from which it is saved in s3 bucket can anyone help ?
here is the code snippet:
FFMpeg::fromDisk('s3')
->open($stored)
->getFrameFromSeconds(02)
->export()
->inFormat(new X264)
->save(uniqid().'thumb.png');