Recent advances in mobile and wireless technologies make possible the bear of new services and the extension of traditional ones in new scenarios. Adaptation strategies play a crucial role in achieving effective solutions for enabling traditional applications to such environments. This paper proposes a video adaptation strategy for real-time multimedia applications, which exploits a novel spacial reduction technique. This technique is suitable for all applications having the need to deliver the best video quality for a particular region of the frame, irrespective of remaining contour. Examples of these applications are those concerning video surveillance. For such applications, it is more important to guarantee the delivery of the only user-selected portion than to deliver the entire, but degraded, video frame when the network conditions are no longer sufficient. Preliminary experimental measurements are conducted in order to evaluate the user subjective satisfaction degree as compared to others well known adaptation strategies proposed in literature.