Paperclip-av-transcoder gem not generating thumbnails from videos

Rails
1

Hi, I am trying to upload videos in my Rails application using the gem
Paperclip-av-transcoder. The videos are being uploaded to my application
successfully but the thumbnails are not being generated.

      Here's my code:-

has_attached_file :movie,
:url =>
“:assets_host/system/:class/:attachment/:id/:style/:filename”,
:path =>
“:rails_root/public/system/:class/:attachment/:id/:style/:filename”,
:medium => { :geometry => “640x480”, :format => ‘mov’, :streaming
=> true },
:thumb => { :geometry => “200x200”, :format => ‘png’, :time => 1 },
:processors => [:transcoder], :swallow_stderr => false

      Can anyone please guide me why is it not generating the

thumbnails ?