A Butterfly Structured Design of The Hybrid Transform Coding Scheme
Venue
Picture Coding Symposium, IEEE (2013), pp. 1-4
Publication Year
2013
Authors
Jingning Han, Yaowu Xu, Debargha Mukherjee
BibTeX
Abstract
The hybrid transform coding scheme that alternates amongst the asymmetric discrete
sine transform (ADST) and the discrete cosine transform (DCT) depending on the
boundary prediction conditions, is an efficient tool for video and image
compression. It optimally exploits the statistical characteristics of prediction
residual, thereby achieving significant coding performance gains over the
conventional DCT-based approach. A practical concern lies in the intrinsic conflict
between transform kernels of ADST and DCT, which prevents a butterfly structured
implementation for parallel computing. Hence the hybrid transform coding scheme has
to rely on matrix multiplication, which presents a speed-up barrier due to
under-utilization of the hardware, especially for larger block sizes. In this work,
we devise a novel ADST-like transform whose kernel is consistent with that of DCT,
thereby enabling butterfly structured computation flow, while largely retaining the
performance advantages of hybrid transform coding scheme in terms of compression
efficiency. A prototype implementation of the proposed butterfly structured hybrid
transform coding scheme is available in the VP9 codec repository.
