Entropy Coding on a Programmable Processor Array for Multimedia SoC

Entropy encoding and decoding is a crucial part of any multimedia system that can be highly demanding in terms of computing power. Hardware implementation of typical compression and decompression algorithms is cumbersome, while conventional software implementations are slow due to bit-level operations, data dependencies and conditional branching. Several solutions have been proposed along the years, ranging from hardware accelerators for high-end systems to careful implementations in VLIW processors and instruction-set extensions, both hardwired and reconfigurable. Multimedia systems must often implement several encoders and decoders for different formats. Hence, a programmable solution is mandatory. However, programmable processors may be challenged by highly-complex algorithms. In this work, a highly efficient and low cost alternative is presented based on an array processor. The dataflow of several entropy coding algorithms has been studied, leading to the choice of an efficient programming model, processor layout and interconnection system. Results are presented for JPEG and H.264 image and video coding standards.