Abstract: A frame-layer rate control method, and a video encoding method and system. In a first-step encoding stage, a QP of a previous frame is used to determine MVs and MB modes for all MBs in a current frame through R-D optimization, and the residual signal is encoded and then decoded for intra prediction. The residual signal is stored and the number of header bits is estimated from the determined MB modes and MVs. Given a target bit-rate for the current frame, a new QP is determined by a rate model. In a second-step encoding stage, the residual signal is encoded and reconstructed for both intra-prediction of subsequent MBs and inter prediction of subsequent frames using the new QP.

Abstract: Task management methods. A plurality of GBL (global bandwidth limiter) classes is provided. One of the GBL classes is selected based on the priority of a first task, in which the first task is from a MCU (micro-controller unit) bus. A system GBL class is selected based on the highest GBL class which has been selected among the GBL classes. A bandwidth limiter of a DMA (direct memory access) unit is assigned according to the system GBL class and the priority of a second task if the DMA unit is activated by the second task. The second task is from a DMA bus, and the cycle between the DMA and MCU buses is determined according to the bandwidth limiter.