Minoru Etoh

Software architecture for flexible and extensible image decoding

Abstract We present a programmable image-decoder architecture for flexible and extensible software implementation. The architecture consists of software modules designed specifically for image-decoding processes, and an interpreter programmable using scripting language. We categorize typical image-decoding processes into bitstream-parsing, image-reconstruction, and data interfacing processes. Since the bitstream-parsing modules and image-reconstruction modules are not coupled in our design, the bitstream syntax can be described solely by bitstream-parsing processes. Moreover, we can modify reconstruction processes without any changes to the bitstream-parsing processes, and vice versa. A script describes an entire sequence of decoding processes, specifying the software modules to be used and their relationships. A set of intermediate codes provides a compact representation of a script. The script interpreter is implemented as a Forth-like stack-based interpreter that selects and executes each module. Adopting the above architecture, we have successfully implemented a programmable software decoder that can perform H.263, MPEG-1 and an original coding scheme that is application-specific.

Motion compensation method for moving pictures with binary shape

This paper describes a motion compensation method for arbitrarily shaped moving visual objects. To utilise both the inter-frame correlation and the texture-shape correlation, we use macroblock-based motion compensation for binary shape coding as well as texture coding. To efficiently achieve motion compensation for a moving binary shape, we introduce extra motion vectors for the shape coding in addition to the texture motion vectors, where the shape motion vectors are coded by referring to the texture motion vectors. The proposed method can successfully save more than 50% of the number of bits in comparison with the intra-only method. The effectiveness of the proposed method has been established through MPEG4 standardisation activity, and the proposed motion-compensation framework has been adopted by the MPEG-4 visual coding standard (ISO 14496-2).