A Fast Intra Skip Detection Algorithm for H.264/AVC Video Encoding

Abstract

A fast intra skip detection algorithm based on the rate‐distortion (RD) cost for an inter frame (P‐slices) is proposed for H.264/AVC video encoding. In the H.264/AVC coding standard, a robust rate‐distortion optimization technique is used to select the best coding mode and reference frame for each macroblock (MB). There are three types of intra predictions according to profiles. These are 16×16 and 4×4 intra predictions for luminance and an 8×8 intra prediction for chroma. For the high profile, an 8×8 intra prediction has been added for luminance. The 4×4 prediction mode has 9 prediction directions with 4 directions for 16×16 and 8×8 luma, and 8×8 chrominance. In addition to the inter mode search procedure, an intra mode search causes a significant increase in the complexity and computational load for an inter frame. To reduce the computational load of the intra mode search at the inter frame, the RD costs of the neighborhood MBs for the current MB are used and we propose an adaptive thresholding scheme for the intra skip extraction. We verified the performance of the proposed scheme through comparative analysis of experimental results using joint model reference software. The overall encoding time was reduced up to 32% for the IPPP sequence type and 35% for the IBBPBBP sequence type.

Intra-Skip in Inter-Frame Coding of H.264/AVC

“…ΔT denotes the percentage of saved encoding time. In the table, Lee's method is in paper [4] and Pan's method is in paper [6] and Kim's method is in paper [7]. They are evaluated against our proposed method.…”

“…Pan et al [6] introduced a new scheme mainly focusing on inter-frame. Recently, Kim et al [7] proposed a simple method which is to adopt minimum RDcost of adjacent blocks as the threshold for intra-skip, and therefore intra-skip is reintroduced in the coding process.…”

Selective intra-prediction Skip Algorithm for inter-frame coding in H.264/AVC

“…The merit of our algorithm mainly comes from selecting the inter mode on the overlapped condition as previously described while discriminating the block that must be coded with 4 × 4 or 16 × 16 intra mode. Kim et al's algorithm [2] achieves a slightly better speed than other algorithms for a "Mobile" sequence that has large motion. However, the time of this algorithm on average was reduced by only 10-16% for the entire coding and 21-31% for the intra-prediction.…”

“…For evaluation, the proposed algorithm, the previously proposed Kim et al's algorithm [2], the previously proposed Mithun et al's algorithm [3], and the full search were simulated on QCIF and CIF sequences in the JM10.1 reference software. And all algorithms are compared to the full search.…”

“…One of approaches to reducing complexity is based on the intraprediction skipping in the inter frame coding. Kim et al proposed a fast intra-skip detection algorithm using the RD costs of neighboring MBs [2]. If the minimum RD cost of neighboring MBs is less than the sum of the absolute differences (SAD) for the current block in the best inter mode, intraprediction is executed.…”