| Abstract: | In this paper, we present a fine-grained parallel implementation of the MPEG-2 video encoder an the Intel Paragon XP/S parallel computer. We use a data-parallel approach and exploit parallelism within each frame, unlike some of the previous approaches that employ multiple processing of several disjoint video sequences. This makes our encoder suitable for real-time applications where the complete video sequence may not be present on the disk and may become available on a frame-by-frame basis with time. The Express parallel programming environment is employed as the underlying message-passing system making our encoder portable across a wide range of parallel and distributed architectures. The encoder also provides control over various parameters such as the number of processors in each dimension, the size of the motion search window, buffer management, and bitrate. Moreover, it has the flexibility to allow the inclusion of fast and new algorithms for different stages of the codec into the program, replacing current algorithms. Comparisons of execution times, speedups, and frame encoding rates using different numbers of processors are provided. An analysis of frame data distribution among multiple processors is also presented. In addition, our study reveals the degrees of parallelism and bottlenecks in the various computational modules of the MPEG-2 algorithm. We have used two motion estimation techniques and five different video sequences for our experiments. Using maximum parallelism by dividing one block per processor, an encoding rate higher than 30 frames/s has been achieved. |
