Architectural Decomposition of Video Decoders by Meansof an Intermediate Data Stream Format

Abstract

The microprocessor industry trend towards many-core architectures introduced the necessity of devising appropriately scalable applications. While implementing software based video decoding, the main challenges are the optimized partitioning of decoder operations, efficient tracking of dependencies and resource synchronization for multiple parallel units. The same applies for hardware implementations of video decoders where monolithic approaches anticipate scalability of the design and reusability of already implemented core components.In this paper, we propose an intermediate data stream format (Meta Format Stream) which is suited for architectural decomposition of video decoding by replacing the conventional monolithic decoder architecture design with a pipelined structure. The Meta Format is forward-oriented and self contained and multistandard capable, so that processing of Meta Streams is independent of the originating bit stream. Our approach does not require special coding settings and is applicable to accelerated decoding of any standards-compliant bit stream. A H.264/AVC multiprocessing proposal is presented as a case study for the potential our our concept. The case study combines coarse grained frame-level parallel decoding of the bit stream with fine-grained macroblock level parallelism in the image processing stage.The proposed H.264 decoder achieved speedup factors of up to 7.6 on an 8 core machine with 2-way SMT. We are reporting actual decoding speeds of up to 150 frames per second in 2160p-resolution.