Zhidan Feng

New rate-distortion modeling and efficient rate control for H.264/AVC video coding

Rate control (RC) is crucial in controlling compression bit rates and qualities for networked video applications. In this paper, we propose a new rate-distortion (R-D) model and an efficient rate control scheme for H.264/AVC video coding, which elegantly resolve the inter-dependency problem between rate-distortion optimization and rate control by eliminating the need of coding complexity prediction for an inter-frame. The objective is to achieve accurate bit rate, obtain optimal video quality while reducing quality variations and simultaneously handling buffer fullness effectively. The proposed algorithm encapsulates a number of new features, including a coding complexity measure for intra-frames, a rate-distortion model, an accurate quantization parameter (QP) estimation for intra-frames, an incremental quantization parameter calculation method for inter-frames, a proportional+integral+derivative (PID) buffer controller, and an intelligent bit-allocation-balancing technique. Our experimental results demonstrate that the proposed scheme outperforms the JVT-G012 solution by providing accurate rate regulation, effectively reducing frame skipping, and finally improving coding quality by up to 1.80dB.

PID-Based Bit Allocation Strategy for H.264/AVC Rate Control

To achieve the best visual quality under the minimum bit rate and the limited buffer size, the rate control allocates appropriate and smooth bits to each frame. This brief proposes an effective bit-allocation strategy for the H.264/Advanced Video Coding rate control. Based on the different characteristics of intraframes and interframes, we introduce the different bit-allocation approaches for them, respectively. A proportional-integer-derivative controller is adopted to minimize the deviation between the target buffer level and the current buffer fullness. To avoid buffer overflow or underflow, a novel setting method for the bit-allocation boundary is presented. Experimental results demonstrate that the proposed bit allocation strategy achieves smooth target bits while better buffer control and visual quality are derived.

New rate-complexity-quantization modeling and efficient rate control for H.264/AVC

In this paper, we propose a novel rate control scheme for H.264/AVC standard, including a new coding complexity measure for intra-frames, a new rate-complexity-quantization (R-C-Q) model, an accurate quantization parameter (QP) estimation for intra-frames, an incremental-control-based QP calculation for inter-frames, and a bit-allocation-balancing technique. Our experimental results demonstrate that, the proposed scheme outperforms the JVT-G012 solution by providing more accurate QP prediction, reducing frame skipping, depressing quality fluctuations, and finally, improving coding quality.

Joint power allocation and rate control for real-time video transmission over wireless systems

We propose a novel rate control algorithm for real-time video transmission over wireless systems, which encompass power control technique, region-based rate control strategy and a macroblock-based segmentation method. By allocating more power as well as more bits to the regions of interest of a video frame and less power & fewer bits to the rest regions, the algorithm improves the visual quality of the regions of interest while saving bits, and also adapts to time-varying wireless channels. When compared with the fixed power MPEG-4 rate control algorithm, the proposed algorithm successfully improves perceptual quality, reduces frame skipping and enhances motion continuity in wireless video transmission, while the total power is kept at the original level

An incremental basic unit level QP determination algorithm for H.264/AVC rate control

In this paper, we propose an incremental-based basic unit (BU) level quantization parameter (QP) determination algorithm for H.264/AVC rate control. Unlike traditional BU level QP computation in existing rate control schemes, the proposed algorithm does not perform target bit allocation and predict coding complexities. Instead, it exploits bit increment to directly determine QP for a BU, aiming at reducing the variations of encoding bits used among BUs within a frame and improve subjective visual quality. To better handle buffer fullness and reduce buffer overflow/ underflow, we explore an enhanced Proportional-Integral-Derivative buffer controller. In addition, the algorithm can also effectively intra-code all frames in a video sequence and has low computational complexity making it suitable for real-time applications. Our experimental results demonstrate that, the proposed algorithm outperforms the rate control algorithm JVT-W042, adopted in the recent H.264/AVC reference model JM13.2, by achieving accurate rate regulation, reducing frame skipping, decreasing quality fluctuation, and improving coding quality up to 1 dB.

A novel total variation based frame layer rate control algorithm for H.264/AVC

Abstract Rate control (RC) plays a crucial role in controlling compression bitrates and encoding qualities for networked video applications. In this research, we propose a new total variation (TV) based frame layer rate control algorithm for H.264/AVC. One of its novelties is that a total variation measure, used in image processing field, is proposed to describe encoding distortion in video compression. For intraframes, we present a TV distortion–quantization ( D TV – Q step ) model to obtain accurate QP step size ( Q step ). Using TV measure to represent frame complexity, we also present an analytic model to calculate Q step for the initial frame, and develop an effective scene change detection method. In addition, an incomplete derivative proportional integral derivative (IDPID) buffer controller is proposed to reduce the deviation between the current buffer fullness and the target buffer fullness, and minimizes the buffer overflow or underflow. Extensive experimental results show that, compared with JVT-W042, the proposed algorithm successfully achieves more accurate target bit rates, reduces frame skipping, decreases quality fluctuation and improves the overall coding quality.

A direct non-buffer rate control algorithm for real time video compression

Rate control (RC) is crucial in controlling compression bitrates and encoding qualities for networked video applications. In this paper, we propose a direct non-buffer real-time rate control algorithm for video encoding, which has two unique features. First, unlike traditional algorithms which adopt buffers in rate control, the proposed algorithm does not use a buffer in rate regulation which can reduce the delay and improve real-time response. Second, we propose a new Proportional-Integral-Derivative (PID) bit controller to directly control encoding bitrates. In addition, we also develop a simple but effective method for real-time target bit allocation. To the best of our knowledge, this is the first work that conducts video rate control without using a buffer. Our extensive experimental results have demonstrated that the proposed algorithm outperforms the MPEG-4 rate control algorithm by achieving more accurate rate regulation and improving overall coding quality.

A Novel Total Variation Measurement Based Intra Frame Rate Control for H.264/AVC

Rate control plays a crucial role in controlling compression bit rates and encoding qualities for networked video applications. The intraframe quantization parameter is very important for enhancing video quality and retaining a limited bit budget. In this paper, we propose a new total variation (TV) measurement based distortion-quantization model, which is found to be a better measurement of perceived image quality than mean squared error. According to the proposed model, at the frame level, we give a method to decide the intraframe quantization step size by the mean distortion of previous coded frames in the last group of picture (GOP) to improve the coding quality and obtain the stable visual quality. In order to further improve Rate Control performance, based on TV measurement, an initial intraframe quantization step size model and a scene change detection method are also proposed. Experimental results show that, when compared with JVT-W042 rate control algorithm, adopted by H.264/AVC standard, the proposed algorithm achieved more accurate rate control in reducing frame skipping, decreasing quality fluctuation and improving the overall coding quality.

A Genetic Rate Control Algorithm for Video Compression

Rate control is crucial in controlling compression bitrates for video encoding. However, most rate control algorithms are heuristic, meaning that they are suboptimal and susceptible to get stuck into local optima. In this paper, we conduct a trial research which applies genetic algorithms to video rate control. Experimental results show that the proposed genetic rate control algorithm works well and achieves global optimal results, which can provide the upper-bound for performance evaluations of heuristic rate control algorithms.