Visual Communication as Event Infrastructure: A Practice-Oriented Case Study of the Tainan SING Era Song Competition

City-based cultural events are not only performances, competitions, or festivals; they have increasingly become platforms for urban cultural communication, public participation, and place-brand formation. In many cultural events, however, visual communication is still treated as back-end promotional packaging, with its function reduced to producing posters, social media graphics, stage backdrops, or promotional materials. This paper argues that visual communication in city-based cultural events is not merely a tool for beautification or publicity, but an event infrastructure that supports how an event is identified, understood, shared, and participated in. Using the Tainan SING Era Song Competition as a case study, this paper examines how visual communication supports the brand recognition, social media visibility, and audience engagement of a city-based music event. The study adopts a practice-oriented case study approach. The research materials include event documents, visual design outputs, social media records, event photographs and videos, and practitioner reflections. It focuses on three questions: how visual identity transformed the event from a call for original song submissions into a recognizable city-based music event; how social media-oriented communication design supported event visibility and information dissemination; and how visual communication and event media created multiple layers of audience engagement. The findings indicate that visual communication was not merely promotional packaging. Through brand identification, information organization, social media content, and event documentation, it supported the communication process from the call for entries, finalist announcement, voting, and the final concert to outcome extension. The paper proposes visual communication as event infrastructure, explaining how visual communication connects cultural policy, original music, social media communication, and public participation in city-based music events.