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-B080 [Y. Chen, L. Yu (Zhejiang Univ.)] Decoder-derived adaptive intra prediction

In this document, a new intra prediction scheme is proposed to improve prediction accuracy and capture the dynamics of different video contents. The scheme adaptively generates optimal intra prediction modes according to the local feature of the coded video. The optimization is conducted by analytical calculations to minimize the prediction residue energy. Experimental results show that the scheme outperforms H.264/AVC in all CFP test sequences and is especially effective for high resolution sequences. Compared to H.264/AVC, the proposed scheme achieves 2.86% average bit rate reduction for all CFP test sequences (Class A to Class E) and 4.42% average bit rate reduction for high resolution sequences (Class A and Class B).

Interpretation of inter prediction as linear matrix operation with boundary pixels as input. Optimize weights in matrix such that the prediction residual is minimized. Derivation is performed at the decoder, usage is signaled to the decoder. Per prediction direction and per block size (4x4 and 8x8) one matrix of size (number of boundary pixels x number of pixels in block) is optimized. Frequency of optimizations is not clearly stated.

Implemented in KTA 2.1. Average gain 2.8 % bitrate saving; higher gains are found for higher resolution sequences, and also by tendency for higher rate.

Encoder run time increase is by less than 2 times, decoder more than 2 times.

Investigation shows that the percentage of usage is also higher for the higher resolutions.

Further study was encouraged, requires significant reduction of complexity (in particular decoder)