I have a multistep form for frontend posting, and I have set the image upload to use the basic uploader instead of the media-library manager :
'id' => $post_type_slug.'step5',
'form' => false,
'fields' => $step5,
'uploader' => 'basic',
The problem is that I want to process a sanitize_file_name() and a file rename() on upload, but wp_handle_upload_prefilter hook seems not available when having a basic uploader. Do you guys have any idea on how I can achieve that?