Enhanced Template-based Intra Mode Derivation with Adaptive Block Vector Replacement

TL;DR

The paper tackles intra prediction inefficiency in ECM by addressing its reliance on adjacent spatial information. It introduces Enhanced Template-based Intra Mode Derivation (E-TIMD) with an Adaptive Block Vector Replacement strategy to extend reference information into non-adjacent regions, supported by a comprehensive BV list construction and AR-BV refinement. A redesigned E-TIMD mode-selection jointly considers angular and BV-based predictions, paired with a HoG-based transform coefficient selection to align predictions with block textures. Empirical results under All Intra show a BD-rate reduction of $0.082\%$ for Y (and $0.25\%$ for screen content) with negligible latency increase, highlighting practical relevance for future video coding standards.

Abstract

Intra prediction is a crucial component in traditional video coding frameworks, aiming to eliminate spatial redundancy within frames. In recent years, an increasing number of decoder-side adaptive mode derivation methods have been adopted into Enhanced Compression Model (ECM). However, these methods predominantly rely on adjacent spatial information for intra mode decision-making, overlooking potential similarity patterns in non-adjacent spatial regions, thereby limiting intra prediction efficiency. To address this limitation, this paper proposes a template-based intra mode derivation approach enhanced by block vector-based prediction. The adaptive block vector replacement strategy effectively expands the reference scope of the existing template-based intra mode derivation mode to non-adjacent spatial information, thereby enhancing prediction efficiency. Extensive experiments demonstrate that our strategy achieves 0.082% Bjøntegaard delta rate (BD-rate) savings for Y components under the All Intra (AI) configuration compared to ECM-16.1 while maintaining identical encoding/decoding complexity, and delivers an additional 0.25% BD-rate savings for Y components on screen content sequences.

Figures (4)

• Figure 1: Illustration of TIMD.
• Figure 2: Illustration of IntraTMP.
• Figure 3: Spatial Sampling of Block Vector.
• Figure 4: The Template Prediction through Block Vector.