Bit Rate Control Algorithm Research Articles

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

Versatile video coding is a new video coding standard that has more capabilities and higher coding efficiency compared with its predecessor. Practical video storage and transmission applications face constrained buffer size and available bandwidth. It is necessary to design the appropriate rate control algorithm to overcome such challenges. In this paper, the non-linear relationship between consumed bits, buffer size, and quantization parameter is estimated by taking the advantages of artificial neural networks, and a rate control algorithm is developed for real-time variable bit rate applications of the versatile video coding standard. The proposed rate control algorithm performs the control action in only one step that results in faster control action. The experimental results show that the proposed algorithm controls the bit-rate as well as the buffer state. Also, the rate–distortion analysis shows that the well-known λ-domain algorithm has only 2.7% bit-rate reduction in comparison with the proposed method.

Mathematical Model of a Network Slicing Approach for Video and Web Traffic

Abstract—This paper presents the study of adaptive bitrate control algorithms used to control the quality of the video stream from video surveillance cameras to remote servers through a live wireless network with video and web traffic. In such a scenario, bitrate control algorithms may select an appropriate video bitrate taking the current state of the camera buffers into account. A mathematical model of video streaming is introduced that allows evaluation of the performance of different bitrate control algorithms.

Bitrate control using a heuristic spatial resolution adjustment for a real-time H.264/AVC encoder

Abstract Conventional bitrate control algorithms that change only the quantization parameter (QP) often suffer from quality degradation when the target bitrate is very low. Therefore, rate control algorithms that adjust spatial resolution in addition to QP control have recently been proposed, but their computations are too complex to be processed in real time. This research proposes a very simple, but effective, rate control algorithm that employs spatial resolution control as well as the existing QP-based bitrate control. The spatial resolution ratio for the best peak signal-to-noise ratio (PSNR) is calculated using a simple estimation model which defines the relationship between the PSNR and the spatial resolution at very low bitrate compression. In the proposed bitrate control algorithm, two scalability tools for adjusting the QP and the spatial resolution ratio are used sequentially to reach the target PSNR and the control decision is made for a group of pictures. Experimental results show that the proposed bitrate control algorithm approximates an optimal solution and yields a better subjective quality as well as objective quality at various bitrates compared to the conventional QP-based bitrate control algorithm. The decision of the control parameters requires very small computational complexity and is made in a completely automatic manner so that the proposed algorithm is well suited for real-time applications.

Low-delay and Ultra-Low-Delay coding in MPEG-4 AAC

MPEG Advanced Audio Coding (AAC) supports 2048-sample windows which give quiet long delay (about 50ms for coder). In this paper we propose AAC Low Delay codecs with 1024-sample window (23ms delay) and Ultra Low Delay codecs with 512-sample window which gives delay about 12ms. LD and ULD can be used in real-time coding e.g. in robots control and very fast voice communication. This design is complete coders and decoders with simple bit-rate control algorithm. Proposed design was implemented in FPGA devices.

Novel bit-rate control algorithm for H.264 based on motion detection

This paper aimed at the rate control problems of JVT-G012,the typical algorithm for H.264/AVC,and presented a new rate control algorithm.After motion detection,if the previous and current frame were in the same complex area,factual encode rate of the previous frame was used to adjust target rate of the current frame.As for the scene changes and high motion video based on motion detection,the minimum sum of squared difference between original and reconstructed pixels after the rate distortion option was used to estimate MAD,and then,MAD was used to compute quantization parameter based on the quadratic model in the process of encoding.The Lagrange parameter can be optimized.The experimental results show that the rate of this algorithm is higher than JVT-G012 and lower than Improvement of H.264AVC by JIANG but the scheme of this paper can effectively improve video quality at scene changes and high motions.Moreover,the scheme also enhances the average PSNR of the test sequences compared to JVT-G012 and JIANG's Improvement.

MPEG-4 constant-quality constant-bit-rate control algorithms

Most constant bit-rate control algorithms aim to produce a bitstream that meets a certain bit-rate with the highest quality. Due to the non-stationary nature of the video sequence, the quality of the compressed sequence changes over time which is not desirable to end-users. In this paper, two constant-quality CBR control algorithms are proposed. They aim to produce CBR bitstream with the highest quality while having low variation in quality. Rather than controlling the quality indirectly as done in previously reported constant-quality control algorithms, they control the quality directly by using quality-matching algorithms. The frame-level Laplacian Constant Quality (FLCQ) algorithm allows one Quantization Parameter (QP) per frame, and uses a new rate-distortion model based on modeling DCT coefficients as having two-sided Laplacian distributions. The macroblock-level Viterbi Constant Quality (MVCQ) algorithm permits the QP to be changed for each macroblock using the Viterbi algorithm which reduces the search complexity. For both algorithms, besides the target bitrate, an extra degree of freedom is introduced that allows trading the variation in quality with the accuracy to the target bitrate. Simulation results show that the proposed algorithms outperform Q2 and TM5 by offering similar or higher PSNR while having lower PSNR variance.

Real-Time Object Segmentation and Coding for Selective-Quality Video Communications

The MPEG-4 standard enables the representation of video as a collection of objects. This paper describes an automatic system that exploits such a representation. Our system consists of two parts: real-time content extraction algorithms and a real-time multi-object rate control method. We present two approaches to content extraction: foreground segmentation based on two cameras and face segmentation based on a single camera. The main contributions of this paper are: 1) under a stereo camera setup, we improve a disparity estimation algorithm to obtain crisp and smooth boundaries of foreground objects; 2) for a single camera scenario, we propose a novel algorithm for face detection and tracking, combining facial color and structure information; and 3) we develop a constant-quality variable bitrate (CQ-VBR) control algorithm that guarantees the quality specification for each object obtained from the two content extraction methods. Both segmentation algorithms run in real-time on a low-cost media processor, and have been tested extensively in various indoor environments. The CQ-VBR control algorithm is a useful tool for the evaluation of object-based coding. For low-bit-rate applications, we can achieve significant reduction in the overall bitrate, while maintaining the same visual quality of the foreground/face object as compared to conventional frame-based coding. Based on tests conducted on several sequences of different complexity levels, the bit-rate savings can be up to 48%. The satisfactory foreground segmentation (results presented) permits porting a live foreground object into arbitrary scenes to create composite video.

An accurate bit-rate control algorithm for video transcoding

In many video based applications, it is essential to precisely control the bit rate of video streams for transmission over different networks and channel bandwidth. One critical element in a bit rate control algorithm is the bit production model that predicts the number of produced bits when a certain quantization parameter is used. In this paper, we present a novel bit allocation and rate control algorithm for compressed domain video transcoding. The specific transcoding issue mentioned is referred to as bit rate adaptation or rate shaping. We first review the architectures of different bit rate adaptation transcoders and the generic rate control problem. Then, we propose and formulate an approximate linear bit allocation model, which is based on experimental results. Based on this model, we propose an adaptive bit estimation and allocation scheme for video transcoding. Implementation results show that the proposed algorithm can provide accurate bit allocation, stable buffer occupancy and improved video quality as compared to existing approaches. This rate control scheme can be used to provide flexible video bit rate adaptation and stable transmission of video streams over heterogeneous networks.

Constrained bit-rate control for very low bit-rate streaming-video applications

We propose a low-complexity frame-layer bit-rate control algorithm for very low bit-rate streaming-video applications with causal one-pass processing. Rate control is achieved by jointly adapting the frame rate and quantization step-size. Constraint coding is introduced, which forces the encoder to operate within a subset of operating points on a 2-D grid. The control parameters are also constrained to change in a gradual fashion, allowing bits to be saved in easy scenes so that more bits can be used for difficult scenes. A simple scene-change detector is used to insert intra frames at scene-change boundaries. The proposed algorithm is implemented in H.263 and is compared with the case of fixed control parameters and a conventional off-line bit-rate control based on adapting the quantization step-size. It is shown that the proposed algorithm codes more frames over a given time interval while achieving average PSNR gains over 1 dB and reducing bit-rate fluctuations. Results are confirmed by subjective tests, which show that our bit-rate control consistently provides improved visual quality.

Bit-rate control algorithm on video packet coding and its characteristics

A bit-rate control method based on a hybrid coding algorithm is proposed for packet video coding. Three types of bit-rate control modes, the constant bit-rate mode, the average bit-rate control mode and the free bit-rate mode, are investigated. According to the opinion test the latter two modes have an advantage in video quality over the constant bit-rate mode. A teleconference terminal, which includes this video codec, audio codec and packet adaptor, is implemented in actual hardware on High-speed Packet Switching system. On this system, video information are transmitted in UI frame (a packet format in X.25 protocol) at 64 K ∼ 800 Kbit/s.