The Joint Collaborative Team on Video Coding (jct-vc) of itu-t wp3/16 and iso/iec jtc 1/sc 29/wg 11 held its second meeting during 21-28 July, 2010 at the itu-t premises in Geneva, ch

JCTVC-B107 [C. Auyeung, A. Tabatabai (Sony)] Intra coding with directional DCT and directional DWT

The Mode Dependent Directional Transform (MDDT) is an option in KTA2.6r1 for the coding of intra block residue. To reduce complexity of MDDT, two types of transforms are proposed to replace MDDT for the transform coding of intra block residuals: Directional Discrete Cosine Transforms (DDCT) and Directional Discrete Wavelet Transform (DDWT). They are applied along and perpendicular to the direction of the intra prediction mode on either 4x4 or 8x8 blocks. In addition, fixed scanning pattern, which is a function of QP and prediction direction, for scanning of the transform coefficients is also proposed. DDCT results in BD-Rate of -1.78% and BD-PSNR of 0.067 dB relative to DCT for CS1. In contrast, MDDT results in BD-Rate of -2.33% and BD-PSNR of 0.087 dB relative to DCT for CS1.

This document proposes to conduct experiment with DDCT as a part of the Transform Tool Experiment of HEVC.

Directional DCT: Re-ordering into a non-rectangular shape where the previous directional orientation becomes horizontal; approach similar to SADCT of MPEG-4.

Quantization similar to MDDT, scanning different.

Implementation in KTA2.6r1.

For inter, approx. 1% worse than MDDT, for all intra, 1.5% worse than MDDT.

Note: For some sequences, DDCT is better than MDDT.

SADCT requires variable length of DCT to be implemented – is this really a complexity advantage?

Contribution noted.