A user terminal device,a server device,a system and a method for assessing quality of media data are described. The user terminal device is used for extracting artefact features from the media data and for communicating the features to the server device which is then used for determining a quality score using the artefacts and an artefact/quality score database accessible by the server device. The score, transmitted to the user terminal device, is presented to a user from which a subjective quality score and a request for re-determination are received which the user terminal device communicates to the server device. This in turn is used for re-determining the quality score and for transmitting back the re-determined quality score wherein the quality score is re-determined using the received artefacts, the received subjective quality score and the artefact/quality score database.