Ultra-high-definition (UHD) audiovisual technology is advancing rapidly, with improvements in resolution (from 4K to 8K), frame rate (up to 120fps), display performance (via HDR and WCG), and immersive audio technologies like 3D Audio. These advancements are driving significant enhancements in content production, transmission, and display capabilities. Additionally, there is a growing demand for intelligence and real-time capabilities, with AI playing a crucial role in content generation and optimization, alongside the need for low-latency transmission in applications such as live broadcasting and interactive media. To support these advancements, digital multimedia interfaces must meet several technical requirements, including higher bandwidth to handle UHD content, lower latency for real-time applications, and the ability to transparently transmit and recognize various formats like HDR metadata and multi-channel audio. Interfaces also need enhanced compatibility and scalability to connect diverse devices and protocols, as well as intelligent negotiation mechanisms for adaptive resolution, refresh rate, and power efficiency. As UHD technology and interface capabilities evolve, they face increasing security threats, necessitating robust content protection mechanisms of advanced digital content protection system to safeguard against potential vulnerabilities, and to meet the content protection requirements for digital multimedia interface, such as efficient encrypted transmission, end-to-end security, multi-stream support, dynamic and adaptive content protection policies, improved interface protocol security, etc. This Recommendation is part 1 of a multipart deliverable composed of two parts. Part 1 describes the requirements of advanced digital content protection (ADCP) system for digital multimedia interfaces, including use case analysis, content protection requirements analysis, reference model, and technical requirements.