If the script is already given by the client, then only dubbing is done in case of script voice over. However, if the script needs to be prepared from the existing or provided video, then we need to transcribe and translate the audio first. Then, the transcribed audio needs to be given voice over, with the help of voice talent. The audio recording must be done with care, as the voice must co-relate with the video perfectly on time. The words transcribed must be meaningful and to the understanding of the audience. It should be audible and interesting to those who watch the video.
More Details – http://vananvoice.com/Script-Voice-over.php