We present a new optimal scheduling algorithm called Periodic Write-Read-Compute (PWRC) scheduling for stream based parallel video processing. Although PWRC scheduling exploits the properties of the video data, it is applicable to any type of periodic data over which a data independent application is to run. The PWRC algorithm is designed considering a bus based parallel architecture allowing point-to-point communication between host and workers. The PWRC requires a high level atomic write-read command for data transmission which can be created in various ways. The analysis of the PWRC provides information either to form a parallel video processing system or to predict the overall performance of an existing system in order to meet real-time requirements of video processing.