Abstract
A new video coding standard H.264/AVC has been recently developed and standardized. The standard represents a number of advances in video coding technology in terms of both coding efficiency and flexibility and is expected to replace the existing standards such as H.263 and MPEG-1/2/4 in many possible applications. In this paper we investigate and present efficient syntax transcoding and downsizing transcoding methods from H.263 to H.264/AVC standard. Specifically, we propose an efficient motion vector reestimation scheme using vector median filtering and a fast intraprediction mode selection scheme based on coarse edge information obtained from integer-transform coefficients. Furthermore, an enhanced rate control method based on a quadratic model is proposed for selecting quantization parameters at the sequence and frame levels together with a new frame-layer bit allocation scheme based on the side information in the precoded video. Extensive experiments have been conducted and the results show the efficiency and effectiveness of the proposed methods.
Highlights
The presence of various efficient video coding standards has resulted in a large number of videos produced and stored in different compressed forms [1]
The first two components focus on the most computationally intensive parts of the H.264/AVC standard to speed up the transcoding process, while the third component aims to achieve a better video quality by enhancing the rate control with the side information extracted from the precoded video
Note that the RD model requires the mean-ofabsolute difference (MAD) of the residue error to estimate the quantization parameter (QP), which is only available after RD optimized process, resulting in a chicken-and-egg problem
Summary
The presence of various efficient video coding standards has resulted in a large number of videos produced and stored in different compressed forms [1]. Intraprediction and coding mode decision in a rate-distortion optimized fashion increase the coding complexity substantially These new features make accurate rate control more difficult and challenging for both coding and transcoding in H.264/AVC standard [9]. We investigate and propose efficient methods for transcoding H.263 video to H.264/AVC standard by exploiting the new coding features. The first two components focus on the most computationally intensive parts of the H.264/AVC standard to speed up the transcoding process, while the third component aims to achieve a better video quality by enhancing the rate control with the side information extracted from the precoded video. Interested readers are referred to [11] for a more comprehensive overview of H.264/AVC
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