Real-time streaming over wireless networks is a challenging proposition due to the highly variable nature of wireless links and the resource-poor nature of mobile device. In such a context, transmission control schemes have to dynamically adapt both to the application requirements and to the channel conditions. In this paper, we propose an adaptive cross-layer quality-of-service (QoS) scheme for wireless channel and streaming applications. For the sake of adaptive QoS, the Cross-layer architecture assumed that layers information could be exchanged between application layers and lower layers. In addition, priority-based adaptive QoS scheduling for MPEG video streams was proposed here. Simulation results show that our cross-layer architecture allows graceful video degradation while minimizing the mean packet delay and frame jitter. Finally, we outline future cross-layer research of multi-play over IP network.