Ki-Hun Han

Improved lossless intra coding for H.264/MPEG-4 AVC

A new lossless intra coding method based on sample-by-sample differential pulse code modulation (DPCM) is presented as an enhancement of the H.264/MPEG-4 AVC standard. The H.264/AVC design includes a multidirectional spatial prediction method to reduce spatial redundancy by using neighboring samples as a prediction for the samples in a block of data to be encoded. In the new lossless intra coding method, the spatial prediction is performed based on samplewise DPCM instead of in the block-based manner used in the current H.264/AVC standard, while the block structure is retained for the residual difference entropy coding process. We show that the new method, based on samplewise DPCM, does not have a major complexity penalty, despite its apparent pipeline dependencies. Experiments show that the new lossless intra coding method reduces the bit rate by approximately 12% in comparison with the lossless intra coding method previously included in the H.264/AVC standard. As a result, the new method is currently being adopted into the H.264/AVC standard in a new enhancement project

Adaptive Single-Multiple Prediction for H.264/AVC Intra Coding

Intra coding is used for reducing the spatial redundancy in video coding. H.264/MPEG-4 advanced video coding (AVC) supports several types of macroblock (MB) mode for Intra coding. Also, each of these MB modes has several directional prediction modes, which significantly improve the Intra coding efficiency, but also increase the encoding complexity. In this letter, we present an adaptive single-multiple prediction method for H.264/AVC Intra coding that not only improves the coding efficiency, but also reduces the encoding complexity. The proposed method adaptively skips the prediction mode bits, so that the encoder complexity can be reduced. The experimental results show that the proposed method achieves a bit-rate reduction of 3.58% and encoding time reduction of 42.4%.

Adaptive intra mode bit skip in intra coding

To reduce spatial redundancies in intra coding, Intra 4times4 mode provides nine directional prediction modes for every 4times4 block. In this paper, an adaptive intra mode bit skip method is proposed to improve coding efficiency in intra coding. The proposed method improves coding efficiency and reduces encoding complexity. Experimental results show that the average bit-rate reduction of 2.86% and 6.58% are achieved at the medium bitrate and low bitrate, respectively. In addition to that, encoding complexity is saved about 42% at the QP values of 27 and 32.

Fast macroblock mode decision in H.264

This paper proposes a fast 16/spl times/16 macroblock (MB) mode decision algorithm, which skips variable block size motion estimation/compensation and spatial-predictive coding in H.264 video coding standard. In experimental results, the encoder using the proposed method runs about 2.76 times as fast as that using H.264 rate-distortion optimization (RDO) tool, while the PSNR (peak signal-to-noise ratio) of the reconstructed images are maintained.