We introduce a fuzzy proportional-integral and derivative (FPI-D) rate control algorithm designed for the variable bitrate (VBR) applications within the H.266/VVC standard. The algorithm operates at the group of picture (GOP) level to minimize unnecessary quantization parameter (QP) fluctuations at the frame level. This approach ensures stable and high visual quality in the encoded video. However, it may lead to increased bitrate variations and buffering delay while the average bitrate converges to the target bitrate in the long term and satisfies the buffer constraints. The proposed algorithm employs an FPI-D controller to compute a base QP for each GOP, considering the buffer status and current bitrate. It then utilizes a new QP cascading model to determine QP offsets for GOP frames. The proposed controller has been implemented in the H.266/VVC reference software (VTM). The rate-distortion (R-D) performance evaluation demonstrates its superiority over the default rate controller employed in the VTM software in terms of peak signal-to-noise ratio (PSNR) and structural similarity index. This achievement includes significant bitrate reductions and quality enhancements while obeying the buffering constraint. Furthermore, its R-D performance is comparable to the constant quantization parameter encoding case, emphasizing its efficiency. Moreover, the buffering delay and mean absolute gradient of PSNR measurements reveal the proposed algorithm’s superiority over the default controller in terms of visual quality. These metrics affirm that compared with the default rate controller, the proposed controller utilizes more efficient buffer space, thus preventing unnecessary QP fluctuations and undesirable PSNR variations.

A neural network-based video bit-rate control algorithm for variable bit-rate applications of versatile video coding standard

In this paper, we propose a novel variable bit rate (VBR) controller for real-time H.264/scalable video coding (SVC) applications. The proposed VBR controller relies on the fact that consecutive pictures within the same scene often exhibit similar degrees of complexity, and consequently should be encoded using similar quantization parameter (QP) values for the sake of quality consistency. In order to prevent unnecessary QP fluctuations, the proposed VBR controller allows for just an incremental variation of QP with respect to that of the previous picture, focusing on the design of an effective method for estimating this QP variation. The implementation in H.264/SVC requires to locate a rate controller at each dependency layer (spatial or coarse grain scalability). In particular, the QP increment estimation at each layer is computed by means of a radial basis function (RBF) network that is specially designed for this purpose. Furthermore, the RBF network design process was conceived to provide an effective solution for a wide range of practical real-time VBR applications for scalable video content delivery. In order to assess the proposed VBR controller, two real-time application scenarios were simulated: mobile live streaming and Internet protocol television broadcast. It was compared to constant QP encoding and a recently proposed constant bit rate (CBR) controller for H.264/SVC. The experimental results show that the proposed method achieves remarkably consistent quality, outperforming the reference CBR controller in the two scenarios for all the spatio-temporal resolutions considered.

Recent advances in wireless technology are enabling the design and deployment of multiservice wireless networks. In order to be able to meet the QoS requirements of the various applications, it is essential to deploy QoS provisioning mechanisms. In this paper we present a QoS framework to support various types of services in a wireless networking environment. In particular, the proposed framework is used to design various QoS provisioning mechanisms for time-constrained variable bit-rate applications. Under this QoS framework we propose various Resource Request (RR) mechanisms. We carry out a comparative study of the proposed schemes. Our simulation results show the effectiveness of the mechanisms when supporting media streaming services, such as MPEG-4 video communications.

At low bit rates, better coding quality can be achieved by downsampling the image prior to compression and estimating the missing portion after decompression. This paper presents a new algorithm in such a paradigm, based on the adaptive decision of appropriate downsampling directions/ratios and quantization steps, in order to achieve higher coding quality with low bit rates with the consideration of local visual significance. The full-resolution image can be restored from the DCT coefficients of the downsampled pixels so that the spatial interpolation required otherwise is avoided. The proposed algorithm significantly raises the critical bit rate to approximately 1.2 bpp, from 0.15-0.41 bpp in the existing downsample-prior-to-JPEG schemes and, therefore, outperforms the standard JPEG method in a much wider bit-rate scope. The experiments have demonstrated better PSNR improvement over the existing techniques before the critical bit rate. In addition, the adaptive mode decision not only makes the critical bit rate less image-independent, but also automates the switching coders in variable bit-rate applications, since the algorithm turns to the standard JPEG method whenever it is necessary at higher bit rates.

A credit-based flow control algorithm for broadband access networks

Evaluation of ABR traffic management under various system time scales

Fuzzy logic control has been employed to improve the rate control mechanism for a MPEG2 video encoder. The data rate of compressed video is controlled by video encoders for either variable bit rate (VBR) or constant bit rate (CBR) applications. In VBR video transmission, it is considered to be more efficient to regulate the video rate by the video coder than by network management in order to avoid network congestion and maintain stable video quality. This rationale can also be applied to CBR transmission. Two fuzzy-logic-based rate control techniques are proposed which maintain the buffer occupancy within a specified range. In the proposed technique for VBR applications, a video quality measure is taken as the crucial control parameter. In CBR rate control, the video data rate or the buffer occupancy is also considered as a fuzzy logic variable. The proposed techniques are designed to control either data rate or video quality, depending on the mode of transmission, i.e. CBR or VBR for the MPEG2 encoder. The performance is compared to a typical VBR MPEG video coder with fixed quantiser step sizes for VBR and also to the CBR video coder with MPEG2 TM5 at typical channel rates. Simulation results are presented with peak signal-to-noise ratio, data rate variation and buffer occupancy as the performance measures.

Achievable QoS and scheduling policies for integrated services wireless networks

Statistics for variable bit-rate digital television sources