Welsh has worked in the cinema industry since 1999. He has been involved in various technology development work during this time, primarily in digital cinema and is named on patents in the area of visual perception of 3D. Welsh started his career at Dolby Laboratories where he held various positions including Film Sound Consultant, Mastering Engineer and Director of Digital Cinema. Subsequently, Welsh became Head of Digital Cinema Operations at Technicolor, where he was the operational lead for Digital Cinema, Localisation and Sound Services. At Technicolor, Welsh was responsible for all mastering, distribution and client services for theatrical releases across their UK facilities. In 2013, Welsh established cloud software company Sundog Media Toolkit. He also lectures in Media Technology at Southampton Solent University, and holds a BSc (Hons) in Media Technology and an honorary Doctor of Technology degree.