Ajax file field upload - change other form field values

Hello,

i've got a file field in my content type. If someone clicks at the upload button next to the browse button, Drupal submits the form via ajax. Is it possible to hook into some function, parse the uploaded file and copy the parsed data for example in another form textfield?

Or asked differently, can I change all form values when a file is uploaded via ajax, or is this possible with the standard form submit only?

Thanks!