Nam-Rye Son

A new macroblock-layer rate control for H.264/AVC using quadratic r-d model

In recent years, rate control is an important technique in real time video communication applications using H.264/AVC. Many existing rate control algorithms employ the quadratic rate-distortion (R-D) model, which is determine the target bits for each I, P, B frame. In this paper, we analysis the problems in rate control for JVT video coding using quadratic R-D model. According to the analysis and experimental results, we present a new frame-layer rate control scheme for JVT video coding based on the quadratic R-D model. Also we estimate the target bit rate for macroblock-layer effectively. The experimental results show that with many scene changes between neighboring frames, existing algorithm exceeded transmission bit rate, while proposed algorithm tranquilized bit rate for stable delivery.

A novel rate-control scheme for H.264 video coding using adaptive quantization parameter

Rate control is an important technique in Constant Bit Rate(CBR) coding. AVC standards contains several inter and intra prediction modes. The current AVC software is difficult to adopt the existing rate control techniques, because the Rate Distortion Optimization (RDO) based on prerequisite quantization parameters determines the optimal prediction of each macroblock. This paper proposes an efficient rate control algorithm at macroblock level for AVC standard by considering adaptive quantization parameter. Experimental results show that the proposed rate control algorithm can accurately achieve the target bit rate. Although the PSNR of object quality of video sequences is degraded a little degraded, but the coding efficiency is similar to or better than of the fixed quantization parameter video coding.

Error Concealment Using Discontinuity Features

In transmitting compressed video bit-stream over Internet, packet loss causes error propagation in both spatial and temporal domain, which in turn leads to severe degradation in image quality. In this paper, a new error concealment algorithm is proposed to repair damaged portions of the video frames in the receiver. Conventional BMA(Boundary Matching Algorithm) assumes that the pixels on the boundary of the missing block and its neighboring blocks are very similar, but has no consideration of edges across the boundary. In our approach, the edges are detected across the boundary of the lost or erroneous block. Once the orientation of each edge is found, only the pixel difference along the expected edges across the boundary is measured instead of the calculation of differences between all adjacent pixels on the boundary. Therefore, the proposed approach needs very few computations and the experiment shows an improvement of the performance over the conventional BMA in terms of both subjective and objective quality of video sequences.

A New Boundary Matching Algorithm Based on Edge Detection

In transmitting compressed video bit-stream over Internet, packet loss causes error propagation in both spatial and temporal domain, which in turn leads to severe degradation in image quality. In this paper, a new error concealment algorithm, called EBMA (Edge Detection based Boundary Matching Algorithm), is proposed to repair damaged portions of the video frames in the receiver. Conventional BMA (Boundary Matching Algorithm) assumes that the pixels on the boundary of the missing block and its neighboring blocks are very similar, but has no consideration of edges across the boundary. In our approach, the edges are detected across the boundary of the lost or erroneous block. Once the orientation of each edge is found, only the pixel difference along the expected edges across the boundary is measured instead of the calculation of differences between all adjacent pixels on the boundary. Therefore, the proposed approach needs very few computations and the experiment shows an improvement of the performance over the conventional BMA in terms of both subjective and objective quality of video sequences.