Motion search method based on zero-block detection in H.264/AVC

Abstract

In order to reduce the computation in the H.264 encoder, a new method for the motion search based on the zero-block detection is proposed in this paper. According to the characteristics of the transform and motion search in H.264, the zero-block detection is performed in the process of the motion search for the inter-frame encoding by comparing the Sum of the Absolute Differences (SAD) to a value related with the Quantization Parameter (QP). The process of the motion search will stop when a zero-block is detected, and the transform and quantization of this zero-block will be skipped, which leads to save a lot of time for the H.264 encoder. Simulation results showed that in contrast with the Jh47.4 video encoder, the proposed method reduces the computations and code length ' without loss of the encoding picture quality, and it is very ef$cient in real time low bit rate video encoding.

Complexity Reduction of H.263 to H.264 Transcoder with Fast Mode Decision

“…As described in the introduction, skip mode detection is used and analyzed in [2], [4], [5]. Those papers focus on fast mode decision and complexity reduction of ME, implying that skip mode detection is an effective method in complexity reduction of H.264 encoder.…”

“…Rate distortion optimization (RDO) algorithm, adopted in mode decision and ME, represents the highest portion in time consumption during encoding and several architectures are proposed to reduce the complexity, such as those described in [2]- [6]. Among those algorithms, zero-block detection using sum-absolutedifference (SAD) threshold is an effective method and [2], [4], [5] use SAD threshold to reduce the complexity of encoder.…”

Exact threshold for zero-block detection in H.264/AVC

“…However, the threshold for the zero-block detection proposed by J.P. Ou et al in [7] is correlated to MF (Multiplication Factor). While the one proposed by Y. Cheng et al in [8] is not the exact threshold either, and it is only the lower limit of threshold for the zero-block detection in H.264/AVC. In this paper the upper limit of threshold for zeroblock detection in H.264/AVC is analyzed in section 2.…”

“…[1,2,3,4,5] [7,8], and the basic idea of such method is as follows: the process of the motion search will stop when a zero-block is detected, then the transform and quantization of this zero-block will be skipped leading to save a lot of time for the H.264/AVC video encoder. Generally speaking, the bigger the threshold is, the higher ratio of skipping zero-block will be, but if the threshold is too bigger, the picture quality will decrease a lot.…”