Audio Video coding Standard (AVS) is established by the Working Group of China in the same name. AVS-video is an application driven coding standard. AVS Part 2 targets to high-definition digital video broadcasting and high-density storage media and AVS Part 7 targets to low complexity, low picture resolution mobility applications. Integer transform, intra and inter-picture prediction, in-loop deblocking filter and context-based two dimensional variable length coding are the major compression tools in AVS-video, which are well-tuned for target applications. It achieves similar performance to H.264/AVC with lower cost.

This paper describes fixed-point design methodologies and several resulting implementations of the Inverse Discrete Cosine Transform (IDCT) contributed by the authors to MPEG's work on defining the new 8x8 fixed point IDCT standard -ISO/IEC 23002-2. The algorithm currently specified in the Final Committee Draft (FCD) of this standard is also described herein.

Adaptive Block-size Transforms (ABT) has been widely used in image/video coding, since it exploits the maximum feasible signal length for transform coding. However, if the transforms in an ABT coding system are Integer Cosine Transforms (ICT), not only separate transform units but also different scaling matrices are required, which consume a vast amount of resources in practical implementations. In this paper, a new approach to compatible ABT is presented, by which 8×8, 8×4, 4×8 and 4×4 transforms can be processed in one transform unit. Furthermore, with Pre-scaled Integer Transform (PIT), the compatibility of scaling matrices especially for 8×4 and 4×8 ICT can be achieved and a single scaling matrix is required. Simulation results and analysis reveal that this approach greatly saves hardware resources and makes the implementation of ABT much easier without loss of performance.

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