After serving in Russia during the Second World War, Stefani attended the Ludwig Maximilian University, where he studied art history, theatre and theology.
[1] Stefani worked as an assistant to the art historian Carl Lamb, and lived in the Federal Republic of Germany.
[1] Stefani's debut film, Zwerg Nase, was released in 1953, followed by Max und Moritz in 1957, for which he wrote the screenplay.
[1] Stefani became famous with the 1957 film The Singing Ringing Tree, for which he led as a guest at the DEFA (GDR) Director.
[1] The film gained "cult status" in the UK after the BBC began screening it regularly.