Variable Bit Rate MPEG Research Articles

Neuro-Fuzzy approach to video transmission over ZigBee

This research paper presents Neuro-Fuzzy applications to Moving Picture Expert Group (MPEG-4) video transmission in IEEE 802.15.4 ZigBee wireless. ZigBee can operate within 2.4GHz frequency with a data rate of 250kb/s, which may interfere with other wireless devices functioning within the same frequency band such as WiFi and Bluetooth. MPEG-4 Variable Bit Rate (VBR) video demands large bandwidth, and may cause data loss and time delay in the data rate limited ZigBee channel as a result of high variation in bit rate. Consequently, it is almost impracticable for MPEG-4 VBR video to be transmitted in the ZigBee channel. This paper introduces two new Neuro-Fuzzy schemes to monitor the input and the output of a data storage entitled traffic-regulating buffer. The input of the buffer is controlled by a Neuro-Fuzzy scheme to ensure that the traffic-regulating buffer neither flooded nor starved with video data. The output of the traffic-regulating buffer is observed by a second Neuro-Fuzzy scheme to make sure the departure-rate conforms to the traffic condition of ZigBee. The simulation results demonstrate that the proposed two Neuro-Fuzzy schemes reduce the excessive data loss and improve the picture quality, as compared with the conventional MPEG-4 VBR video over ZigBee.

Transcoding-after-Smoothing System for VBR MPEG Video Streaming

Delivering video streaming service over the Internet encounters some challenges. Two of them are heterogeneity of networks capacity and variability of video data rate. The capacity of network segments are constrained. Meanwhile, the rate of video data to be transmitted is highly variable in order to get near-constant images quality. Therefore, to send variable bit rate (VBR) video data over capacity-constrained network, its bit rate should be adjusted. In this paper a system to adjust the transmission bit rate of VBR MPEG video data called Transcoding-after-Smoothing (TaS), which is a combination of bit rate transcoding and bit rate smoothing algorithm, is proposed. The system smoothes out transmission rate of video data while at the same time also performs transcoding on some video frames when necessary in order to keep the transmission bit rate below a certain threshold value. Two kinds of TaS methods are proposed. One method does not have transcoding preference, while the other method uses frame type preference where an intra-coded frame is the last one that will be transcoded. These methods are implemented in our video server where a VBR video data is accessed by a client. Our experiment results show that the first TaS method yields significant reduction in the number of transcoded frames compared with the second TaS method and conventional frame-level transcoding. However, the second method performs better in minimizing the quality distortion.

Effect of Delay and Buffering on Jitter-Free Streaming Over Random VBR Channels

We study the optimal streaming of variable bit-rate (VBR) video over a random VBR channel. The goal of a streaming application is to enable the successful decoding of each video object before its displaying deadline is violated. Hence, we define the main performance metric of a streaming system as the probability of un-interrupted video presentation, or jitter-free probability. Previous literature has described solutions to estimate the jitter-free probability by assuming either independence in the encoded data process or simplistic channel models. In this work, we present a novel analytical framework, which requires only some basic statistical information of an arbitrary VBR channel, to bound the probability of jitter-free playout under the constraint of initial playout delay and receiver buffer size. Both the infinite and finite buffer cases are considered. This technique is then applied to investigate streaming over a wireless system modeled by an extended Gilbert channel with ARQ transmission control. Experimental results with MPEG-4 VBR encoded video demonstrates that the proposed analysis derives close bounds to the actual system performance. Finally, we show that the proposed analysis provides a theoretical foundation to quantify the tradeoffs between the initial playout delay, the receiver buffer size, and the jitter-free probability for a general class of VBR streaming over random VBR channels.

Accurate Prediction of Real-Time MPEG-4 Variable Bit Rate Video Traffic

In this letter, we propose a novel algorithm to predict MPEG-coded real-time variable bit rate (VBR) video traffic. From the frame size measurement, the algorithm extracts the statistical property of video traffic and utilizes it for the prediction of the next frame for I-, P-, and B- frames. The simulation results conducted with real-world MPEG-4 VBR video traces show that the proposed algorithm is capable of providing more accurate prediction than those in the research literature.

Neuro-Fuzzy Control for MPEG Video Transmission Over Bluetooth

The application of a neuro-fuzzy (NF) controller to moving picture expert group (MPEG-2) video transmission over a Bluetooth asynchronous connectionless (ACL) is presented in this paper. MPEG variable bit rate (VBR) data sources experience unpredictability, long delay, and excessive loss, due to sudden variations in bit rate. Therefore, it is practically impossible to transmit MPEG-2 VBR video sources over a Bluetooth channel with a limited transmission speed and considerable wireless interferences without loss of data or image quality degradation. In this work, a traffic-shaping buffer is introduced before the host controller interface (HCI) of the Bluetooth protocol stack to obstruct excessive MPEG VBR data sources during the peak transmission periods. An integrated neuro-fuzzy controller monitors and reduces the burstiness of the traffic-shaper output rate to facilitate the MPEG VBR video sources to conform to the token-bucket contract before entering the Bluetooth channel. A conventional rule-based-fuzzy (RBF) controller oversees the arrival rate to the traffic-shaper to avoid saturation or starvation of the buffer. The computer simulation results demonstrate that applications of the NF and RBF schemes reduce excessive delay and data loss at the HCI as compared with conventional video transmission in Bluetooth ACL links

Dynamic Bandwidth Allocation Based on Online Traffic Prediction for Real-Time MPEG-4 Video Streams

The distinct characteristics of variable bit rate (VBR) video traffic and its quality of service (QoS) constraints have posed a unique challenge on network resource allocation and management for future integrated networks. Dynamic bandwidth allocation attempts to adaptively allocate resources to capture the burstiness of VBR video traffic, and therefore could potentially increase network utilization substantially while still satisfying the desired QoS requirements. We focus on prediction-based dynamic bandwidth allocation. In this context, the multiresolution learning neural-network-based traffic predictor is rigorously examined. A well-known-heuristic based approach RED-VBR scheme is used as a baseline for performance evaluation. Simulations using real-world MPEG-4 VBR video traces are conducted, and a comprehensive performance metrics is presented. In addition, a new concept of renegotiation control is introduced and a novel renegotiation control algorithm based on binary exponential backoff (BEB) is proposed to efficiently reduce renegotiation frequency.

Kalman optimized model for MPEG-4 VBR sources

This paper presents a traffic prediction method for MPEG-4 (Moving Picture Experts Group) VBR (Variable Bit Rate) videos. No previous knowledge of the traffic statistics is needed when Kalman optimized method is applied to modeling and predicting MPEG-4 video traffic. The GoP (group of pictures) loss probabilities in actual traffic are a very close approximation to those in our prediction traffic and the prediction errors are very small. Simulations show our prediction method for future GoP is effective and applicable to real time video traffic prediction and resource reservation.

Impact of local coding efficiency on the modelling of flows derived from VBR MPEG2 video coding

AbstractThis Letter proposes a cell generation model based on a MMPP(2) process which aims to simulate the unsmoothed data output from a variable bit rate (VBR) MPEG‐2 video encoder. By taking into account the coding efficiency in some image zones, we have improved the modelling. This coding efficiency is directly related to the properties of the compression methods used and may lead to a periodic phenomena given the inter‐arrival times between data. The developed model integrates this periodicity in order to refine the modelling. Experimental simulations of VBR MPEG video transmission over ATM were performed to validate this approach. The results expressed in terms of the inter‐arrival time characteristics show the improvement brought by accounting for local coding efficiency. Copyright © 2004 AEI

Efficient traffic prediction scheme for real-time VBR MPEG video transmission over high-speed networks

The efficient transportation of real-time variable bit rate (VBR) video traffic in high-speed networks is currently an active area of research. The capability to predict VBR video traffic can significantly improve the effectiveness of numerous management tasks, including dynamic bandwidth allocation and congestion control. This paper proposes an adaptive traffic prediction method for VBR MPEG videos, a major multimedia application. Rapid traffic variations due to scene changes are analyzed, then a prediction scheme using the identification of scene changes related to I and P frames is presented. For predicting multiplexed MPEG traffic, a prediction interval is derived that represents a highly correlated traffic sequence. In addition, to reduce the prediction error, a less fluctuating signal instead of the original multiplexed traffic is used as the input for the predictor. Simulation results show that the proposed method is able to predict the original traffic more accurately than the conventional LMS method.

A Computation Method for Providing Statistical Performance Guarantee to an ATM Switch 1

ATM is a connection-oriented technology and messages are divided into fixed size packet called cells to facilitate communications. However, before two hosts can communicate, a connection has to be established between them. Consider a real-time communication application running on top of an ATM network. In order to provide the real-time service, we require the network to provide a performance guarantee for the connection. There are two types of performance guarantees: deterministic and statistical guarantees. While a deterministic guarantee provides an absolute bound on the worst case cell delay experienced in an ATM switch, a statistical guarantee provides a probabilistic bound on the worst case cell delay. In this paper, we use a self-similar stochastic process to characterize the arrival of the real-time traffic. Extending from our previous work on deterministic delay guarantee, we provide methods for determinating the statistical delay bound for the worst case cell delay in an ATM switch with various output port controllers. We conclude this paper with two case studies: one based on ordinary LAN traffic and one on the variable bit-rate MPEG video transmission of the movie “Star Wars”. To show the effectiveness of our statistical delay guarantee, we compare it with the delay derived by Cruz as well as the actual cell delay determined by the two traffic traces.

MPEG VBR video traffic modeling and classification using fuzzy technique

We present an approach for MPEG variable bit rate (VBR) video modeling and classification using fuzzy techniques. We demonstrate that a type-2 fuzzy membership function, i.e., a Gaussian MF with uncertain variance, is most appropriate to model the log-value of I/P/B frame sizes in MPEG VBR video. The fuzzy c-means (FCM) method is used to obtain the mean and standard deviation (std) of T/P/B frame sizes when the frame category is unknown. We propose to use type-2 fuzzy logic classifiers (FLCs) to classify video traffic using compressed data. Five fuzzy classifiers and a Bayesian classifier are designed for video traffic classification, and the fuzzy classifiers are compared against the Bayesian classifier. Simulation results show that a type-2 fuzzy classifier in which the input is modeled as a type-2 fuzzy set and antecedent membership functions are modeled as type-2 fuzzy sets performs the best of the five classifiers when the testing video product is not included in the training products and a steepest descent algorithm is used to tune its parameters.

Design of a fair bandwidth allocation policy for VBR traffic in ATM networks

Since real-time variable bit rate (VBR) traffic is inherently bursty, dynamic bandwidth allocation is necessary for ATM streams that carry VBR traffic. In order to provide quality-of-services (QoS) guarantees and to reduce the computational complexity, an hybrid of guaranteed and dynamic adaptive allocation scheme requires to be implemented. Typical dynamic allocations to competing streams are done in the form of linear proportions to the bandwidth requirements. We show that during temporary link congestion such proportional arrangements can give rise to unequal queue growth and, subsequently, degraded QoS. This is found to be true even for streams that belong to the same VBR class and share identical long term traffic characteristics and QoS requirements. In this paper, four allocation algorithms are presented and analyzed in terms of their fairness and QoS potential for real-time VBR traffic. We propose and show that a novel allocation strategy, termed Minmax, solves the mentioned problem of unfairness within a class. By maintaining a fair distribution of buffer length across the streams of a class, the proposed policy can achieve better and fairer QoS performance compared to the traditional methods. We present analytical results, proofs and a simulation study of the described algorithms. Four allocation policies for handling MPEG VBR video streams are simulated in the context of a wireless ATM (WATM) medium access control. The results show that in certain scenarios, the Minmax strategy can reduce losses by an order of magnitude, while decreasing delays substantially.

End-to-end delay analysis of videoconferencing over packet-switched networks

Videoconferencing is an important global application-it enables people around the globe to interact when distance separates them. In order for the participants in a videoconference call to interact naturally, the end-to-end delay should be below human perception; even though an objective and unique figure cannot be set, 100 ms is widely recognized as the desired one-way delay requirement for interaction. Since the global propagation delay can be about 100 ms, the actual end-to-end delay budget available to the system designer (excluding propagation delay) can be no more than 10 ms. We identify the components of the end-to-end delay in various configurations with the objective of understanding how it can be kept below the desired 10-ms bound. We analyze these components step-by-step through six system configurations obtained by combining three generic network architectures with two video encoding schemes. We study the transmission of raw video and variable bit rate (VBR) MPEG video encoding over (1) circuit switching; (2) synchronous packet switching; and (3) asynchronous packet switching. In addition, we show that constant bit rate (CBR) MPEG encoding delivers unacceptable delay-on the order of the group of pictures (GOP) time interval-when maximizing the quality for static scenes. This study aims at showing that having a global common time reference, together with time-driven priority (TDP) and VBR MPEG video encoding, provides adequate end-to-end delay, which is (1) below 10 ms; (2) independent of the network instant load; and (3) independent of the connection rate. The resulting end-to-end delay (excluding propagation delay) can be smaller than the video frame period, which is better than what can be obtained with circuit switching.

Bandwidth renegotiation with traffic smoothing and joint rate control for VBR MPEG video over ATM

Variable bit-rate (VBR) MPEG video traffic is highly bursty due to group of pictures structure, and shows time-variant statistical characteristics due to scene changes. These characteristics make it more difficult to manage network resources, and leads to the significant reduction in network utilization. We deal with the issues related to efficiently transmitting VBR MPEG video traffic over asynchronous transfer mode networks, while maintaining consistent visual quality and improving network utilization on the basis of real-time applications. First, we propose a joint encoder and channel-rate control scheme that comply with not only negotiated traffic parameters, but also constraints imposed by encoder and decoder buffers. Second, we propose a dynamic bandwidth renegotiation method by combining the above scheme with a traffic smoothing method that can make the peak rate close to the sustainable rate. The efficiencies of the proposed methods are compared with a few other competitive schemes such as transmission methods for unconstrained VBR and the constant bit-rate scheme with average bandwidth equal to that of the proposed methods.

Starting time selection and scheduling methods for minimum cell loss ratio of superposed VBR MPEG video traffic

The arrangement of the I-picture starting times of multiplexed variable bit rate (VBR) MPEG videos may significantly affect the cell loss ratio (CLR) characteristics of superposed traffic. In this paper, we deal with the problems due to the starting time arrangement of VBR MPEG videos. VBR MPEG video traffic is modeled by a sequence with time-varying and periodic picture-type dependent rate envelopes. From extensive investigations into the relationships between the starting time arrangement and the queueing performance, it is shown that the average power of superposed VBR MPEG video traffic can be a good measure for the burstiness of the traffic. Then, we can derive a starting time selection method for a newly requested VBR MPEG video that can minimize the CLR as well as the peak cell rate of the superposed traffic including the new request itself, and an efficient scheduling method called MC-scheduling is also proposed as an application of the starting time selection method. The exactness and efficiencies of the proposed methods are shown by comparing them with other scheduling methods in terms of the smoothness and the CLR performances.

Quality-optimised MPEG2 video data rate control using fuzzy logic techniques

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.

Connection admission control with picture-type dependenteffectivebandwidths for VBR MPEG video traffic in ATM networks

The I-picture starting time distribution of variable bit rate (VBR) MPEG video sources may significantly affect the cell loss characteristics of ATM multiplexers. The authors propose a new connection admission control (CAC) method which can reflect this effect. For CAC, VBR MPEG video traffic is modelled as a composite sequence of three subsequences with different effective bandwidths according to their picture coding types. Experimental results show that the proposed method can fully reflect this effect due to the starting time distribution while also improving network utilisation significantly.

Joint rate control for VBR MPEG video on PVC ATM links

A joint rate control algorithm for variable bit rate(VBR) MPEG-compressed digital video on point-to-point permanent virtual circuit (PVC) ATM links is proposed.The algorithm controls the encoding mode of a numberof video encoders that operate either on VBR or constantbit rate (CBR) mode. The algorithm selects the encodingmode based on the buffer occupancy of a multiplexer co-located with the encoders that interfaces them to the PVClink. VBR encoding is the predominant encoding mode usedduring congestion-free periods. CBR mode is used only during congested periods. When CBR is selected, new bit ratesare jointly assigned to the encoders based on their relativeencoding complexities. The bit rate assigned to the encodersare enforced by a CBR rate control local to each encoder.The performance of the joint rate control algorithm is evaluated through simulation of a packet multiplexer, where anumber of connections are multiplexed onto a fixed-capacity channel. The performance is compared to that of multiplexing conventional CBR and open-loop VBR from the videoquality and bandwidth efficiency points of view. Simulation results show that the proposed algorithm improves performance over multiplexed conventional CBR or open-loop VBR MPEG video, without significantly increasing implementation complexity. The application of the algorithm, tovideo-on-demand over ATM is discussed.

A high quality VBR MPEG system for Internet and broadcasting applications

A high quality variable bit rate (VBR) MPEG-2 encoding scheme that offers optimum video quality and bandwidth allocation is presented. This scheme utilizes a real-time bit redistribution method, insertion of I frames at scene changes and large GOP (group of pictures) size to produce high picture quality. An encoders-bank with predetermined sets of nominal-long-term, minimum and maximum bit rates in combination with a sophisticated picture quality control process allows a bit rate selector to choose the optimum bit stream from a set of encoders, thus resulting in a high quality VBR video stream. The proposed scheme is very easy to implement and offers an efficient real-time VBR solution for broadcasting applications that involve multiplexed distribution of multiple video sources.

SIMULATION AND MODELLING OF VARIABLE BIT RATE MPEG VIDEO TRANSMISSION OVER ATM NETWORKS

This paper proposes an efficient transmission mechanism based on frame spreading, for variable bit rate (VBR) MPEG compressed video, through an asynchronous transfer mode (ATM) multiplexer, such as a cable head-end. We implement a priority scheme in a software MPEG encoder which produces proportionate traffic in both (i.e. high and low) priority partitions for all three types of video frames used in MPEG, i.e. intraframe (I), predicted (P) and bidirectionally interpolated (B). Furthermore, we simulate an ATM multiplexing scheme with a pushout buffer mechanism providing priority scheduling at the multiplexer for the two video partitions. We load the multiplexer with VBR MPEG traffic and collect performance statistics such as the cell loss ratios for various frame spreading scenarios. In order to study the transmission mechanisms via simulation, we develop two statistical models, using the transform-expand-sample technique (TES) for VBR MPEG video with two levels of priority. The first model is matched with the empirical histogram and autocorrelation function of each frame type (I, P and B). The second model is created with the assumption of a gamma distribution for the number of bits in each frame type. We conduct experiments using both models and compare the results.