Frame-layer Rate Control Research Articles

CTU Layer Rate Control Algorithm in Scene Change Video for Free-Viewpoint Video

At present, the rate control algorithm for multiview high-efficiency video coding (MV-HEVC) does not have the capability of efficient coding tree unit(CTU) layer bit allocation, and the video quality varies greatly for sequences with sudden scene changes or large motions. To overcome this limitation, this paper proposes a rate control algorithm for MV-HEVC based on scene detection. Firstly, we established ρ domain rate control model based on multi-objective optimization. Then, it uses image similarity to make reasonable bit allocation among viewpoints. If the video scene is switched, the image similarity is recalculated, and then the correlation between the weights of the interview point rates and the correlation between the viewpoints are analyzed. Finally, the frame layer rate control considers the layer B-frame and other factors in allocating the code rate, and the basic unit layer rate control adopts different quantization methods according to the content complexity of the CTU. Experimental results show that the proposed rate control algorithm can maintain good coding efficiency and decrease the average video quality variation by 25.29%.

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

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 (DTV–Qstep) model to obtain accurate QP step size (Qstep). Using TV measure to represent frame complexity, we also present an analytic model to calculate Qstep 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.

FMO-based H.264 frame layer rate control for low bit rate video transmission

Abstract The use of flexible macroblock ordering (FMO) in H.264/AVC improves error resiliency at the expense of reduced coding efficiency with added overhead bits for slice headers and signalling. The trade-off is most severe at low bit rates, where header bits occupy a significant portion of the total bit budget. To better manage the rate and improve coding efficiency, we propose enhancements to the H.264/AVC frame layer rate control, which take into consideration the effects of using FMO for video transmission. In this article, we propose a new header bits model, an enhanced frame complexity measure, a bit allocation and a quantization parameter adjustment scheme. Simulation results show that the proposed improvements achieve better visual quality compared with the JM 9.2 frame layer rate control with FMO enabled using a different number of slice groups. Using FMO as an error resilient tool with better rate management is suitable in applications that have limited bandwidth and in error prone environments such as video transmission for mobile terminals.

A reformative frame layer rate control algorithm for H.264

Rate control is an important part of video coding. There are two disadvantages in frame layer rate control of JVT-G012 proposal for H.264 video coding standard. One is that the bit allocation in frame layer is uniform and another is that it does not take the encoded frame information into account. This paper presents a reformative frame layer rate control algorithm by combining frame complexity and adjusting quantization parameter (QP). The target bits of each frame are allocated based on its complexity coefficient and then its quantization parameter is adjusted by encoded frame information. Experimental results show that the proposed algorithm, in comparison to the original algorithm, reduced the actual bitrate error of video sequences by almost one times, improved average peak signal noise ratio (PSNR) by 0.64 dB and got a smaller PSNR deviation by 29.32%. The algorithm can not only control bitrate more accurately, but also get video image quality better and smoother with lower coding buffer occupancy.

Improved frame-layer rate control algorithm for H.264

A new rate control algorithm based on scene change was proposed on the basis of H.264 frame-layer.The complexity of image was measured by the weighted sum of the ratio of Mean Absolute Difference(MAD) of P-frame luma coeffecient and the relative changes of YUV's mean value,then the target rate was allocated and the quantitative parameters were adjusted according to the complexity.Meanwhile the target rate can be adjusted by using bits compensative factor.Compared to the algorithm in JVT-G012,the experimental results under the JM10.2 show that both the accuracy of rate controlling and the quality of reconstructed images can be improved if using the algorithm.

Frame layer rate control for H.264/AVC with hierarchical B-frames

Hierarchical B-frames contribute to improvement of coding performance when introduced into H.264/AVC. However, the existing rate control schemes for H.264/AVC, which are mainly applied to IPPP and IBBP coding structures, cannot work efficiently for the coding structures with hierarchical B-frames. In this paper, a frame layer rate control scheme for hierarchical B-frames is proposed. Firstly, an adaptive starting quantization parameter (QP) determination method is implemented to derive the QP for the first coding frame based on the available channel bit rate and the content of the current video sequence. Then, the target bit budget for a group of pictures (GOP) is calculated based on the target bit rate and the buffer status. Afterwards, a temporal level (TL) layer rate control phase is introduced, and the GOP layer target bit budget is allocated to each TL. In the frame layer rate control phase, a method based on a rate-distortion model and the coding properties of the previous coded key frames is derived to determine the QP for the current key frame. For hierarchical B-frames, we introduce a typical weighting factor in the determination of their target bit budgets to address the features of the hierarchical coding structures. This weighting factor is calculated according to the target bit budget of the GOP layer and the knowledge obtained from the previous coded B-frames in each TL. Subsequently, the QP for coding the current B-frame is computed by a quadratic model with different model parameters for different TLs, and the computed QP is further adaptively adjusted according to the usage of the target bit budgets. After coding the current frame, an update stage, in which a threshold-based method is integrated to avoid model degradation, is invoked to update the parameters for rate control. Experimental results demonstrate that when the proposed rate control scheme is applied to the coding structure with hierarchical B-frames in H.264/AVC, the actual coding bit rates can match the target bit rates very well, and the encoding performance is also improved.

Lightweight content-adaptive coding in joint analyzing-encoding framework

A novel joint analyzing-encoding framework is proposed in this paper. With this framework, the video analysis and the video coding can be integrated together, which can decrease the computational complexity of the video process system due to the obtained shared information. A lightweight content-adaptive video coding scheme can be achieved by using the presented framework for H.264 standard. The side encoding information, including motion vectors (MVs) and sum of absolute differences (SADs), can be used to reduce the computation cost of the moving region analysis. First, the rectangular shape and the displacement information of the moving region in the current encoded frame are obtained by employing a robust binary detection method, which is based on the adaptive threshold and the fast components labeling algorithm. Then, the rectangular shape information of the next frame is achieved by using a simple but effective prediction method, which considers the principle of the temporal motion constraint. Finally, a motion importance mask map (MIMP) is obtained according to the predicted rectangular shape information. Meanwhile, a category of frequency coefficient suppression(FCS) technique in the transform domain is presented to avoid the use of the complex MB-layer rate control method. With MIMP and FCS, a lightweight content-adaptive video coding scheme is realized based on a simple frame-layer rate control method. Experimental results show that the proposed scheme can detect and predict the moving regions fast and improve the objective/subjective visual quality significantly for the moving regions.

Improved H.264 frame-layer rate control for low bit rate video with high motion

In the existing frame-layer rate control for H.264, buffer status and content complexity are used improperly, causing quality fluctuations of high-motion video at low bit rates and high frame rates (under 19.2 kbps at 30 fps). We propose an improved H.264 frame-layer rate control scheme to obtain steady video quality and stable buffer management. Experimental results showed that the proposed scheme performed better than existing schemes.

On Lagrange multiplier and quantizer adjustment for H.264 frame-layer video rate control

H.264/AVC encoder employs a complex mode-decision technique based on rate-distortion optimization. It calculates rate-distortion cost (RDcost) for all possible modes to choose the best one having the minimum RDcost. This paper presents a frame-layer rate control for H.264/AVC that computes the Lagrange multiplier (/spl lambda//sub MODE/) for mode decision by using a quantization parameter (QP) which may be different from that used for encoding. At the same time, we also compare actual bits produced by previous macroblocks (MBs) with the total bits allocated to these MBs to further modify /spl lambda//sub MODE/. The objective of these measures aims to produce bits as close to the frame target bits for rate control as possible. This is very important in the case of low-bit-rate tight buffer applications. In order to obtain an accurate QP for a frame, we employ a complexity-based bit-allocation scheme and a QP adjustment method. Simulation results comparing with the H.264 Joint Video Team (JVT) rate control method show that the H.264 encoder, using the proposed algorithm, achieves a visual quality improvement of about 0.56 dB, performs better for buffer overflow and underflow, and achieves a smaller PSNR deviation.

A Region-Based H.263+ Codec and Its Rate Control for Low VBR Video

This paper presents a region-based video codec, which is compatible with the H.263+ standard, and its associated rate control algorithm for low variable-bit-rate (VBR) video. The proposed region-based coding scheme is a hybrid method that incorporates traditional block DCT coding as well as object-based coding. To achieve this, we adopt H.263+ as the platform, and develop a fast macroblock-based segmentation method to implement the new region-based codec. The associated rate control solution includes rate control in three levels: encoding frame selection, frame-layer rate control and macroblock-layer rate control. The goal is to improve human visual perceptual quality at low bit rates. The efficiency of the proposed rate control algorithm applied to the region-based H.263+ codec is demonstrated via several typical test sequences.

Efficient real-time frame layer rate control technique for low bit rate video over WLAN

A real-time frame-layer rate control algorithm is proposed for low bit rate video coding over IEEE 802.11 wireless local area network (WLAN). The proposed rate control method performs bit allocation at the frame level to minimize the average distortion over an entire sequence as well as variations in distortion between frames. A new frame-layer rate-distortion model is derived, and a non-iterative optimization method is used for low computational complexity. The proposed algorithm produces low encoding time delay, and is suitable for real-time low-complexity video encoder. Experimental results indicate that the proposed control method provides better visual and PSNR performance than the existing TMN8 rate control method.