A MediaFoundation developer works with Microsoft's Media Foundation framework, a COM-based multimedia framework in Windows Vista and later. They design and develop digital media applications, such as audio/video playback and recording, video editing, and video streaming. They handle media processing tasks, such as decoding, encoding, and processing media data. They use the Media Foundation API to manage digital media, dealing with various media types and formats. They also troubleshoot and optimize media applications for better performance. Additionally, they often collaborate with other developers, UX designers, and stakeholders to ensure applications meet user needs and business requirements.