Software architecture for flexible and extensible image decoding

摘要

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.