Research on Quality of Service (QoS) in Wireless Multimedia Sensor Networks (WMSNs) focuses on ensuring reliable transmission of multimedia data such as audio, video, and images while maintaining energy efficiency and low latency. Unlike traditional WSNs, WMSNs require higher bandwidth, lower delay, and minimal packet loss to support real-time applications. Recent advancements propose energy-efficient QoS-aware routing protocols that balance multimedia quality with node lifetime by dynamically adjusting transmission power and data rate. Cross-layer optimization and reinforcement learning-based routing are increasingly used to adapt to varying network conditions and traffic loads. Techniques such as priority-based packet scheduling, congestion control, and multi-path transmission further enhance end-to-end performance. Overall, QoS in WMSNs aims to achieve a balance between performance metrics and energy constraints, ensuring smooth delivery of multimedia content in resource-limited sensor environments.