MPEG-4 Video Transmission Research Articles

Hierarchical Packet Pre-dropping Approach for Improved MPEG-4 Video Transmission in Heavily Loaded Wireless Networks

In this study, we develop a hierarchical packet pre-dropping (HPPD) approach that exploits different methods to process intra-coded (I)/predictive-coded (P)/bidirectionally predictive-coded (B) video frame packets to improve the video transmission quality in heavily loaded IEEE 802.11e wireless local area networks (WLANs). It is not easy to transmit packets in WLANs with a heavy traffic load. Efficient transmission of video packets is important for improving the quality of video transmission. If the network becomes congested, important packets may be dropped. Further, video packets tend to be affected considerably more than data packets. Therefore, controlling the traffic of insignificant packets to avoid the transmission of useless data can improve the quality of video transmission. On the basis of this concept, in this paper, we propose a strategy that is different from the approaches proposed in earlier studies. First, identification of the dependence of video frames in a group of pictures (GOP) can prevent the transmission of useless data. Thus, the transmission channel resources are economized by avoiding the transmission of undecodable video frames. Second, in heavily loaded WLANs, it is not sufficient to utilize the queues to transmit important video frame packets. HPPD adopts the method of an aggressive drop of unimportant packets to retain the transmission channel resources for important video packets. Experiments have demonstrated that in heavily loaded WLANs, the Peak Signal to Noise Ratio (PSNR) for the case when the HPPD mechanism is adopted is better than that when enhanced distributed channel access (EDCA), adaptive mapping, or a novel mapping mechanism is used.

Joint source channel coding with unequal error protection and quality biased rate allocation for MPEG-2 video transmission

In recent years the importance of video communication has been increased many folds. In this paper, we propose an information significance biased bit allocation technique for rate distortion optimisation. First MPEG-2 compressed bitstreams are separated in different layers. Each layer effect in received quality due to channel constrains decides the priority of the layer and the required level of Unequal Error Protection (UEP). Results indicate that Joint Source Channel Coding (JSCC) with UEP for three-layer (I, B, P frames) defined as UEP3 can lead better acceptable quality of video in noisy environment compared to 1-layer Equal Error Protection (EEP) and 2-layer (Base layer and Enhancement Layer) UEP2 coding approach. Further PSNR of UEP3 method can be improved using layering of I frame Blocks. Blocks are classified into strong informative and marginal informative category by considering the local variance and grey scale gradient distribution and protection are assigned.

Frame-based mapping mechanism for energy-efficient MPEG-4 video transmission over IEEE 802.11e networks with better quality of delivery

Recent developments in hardware, software and communication technologies have resulted in increasing interest in the use of wireless local area networks (WLANs). Mobile devices with embedded WLAN functionality are becoming increasingly popular. Such devices must be designed to support applications that require high quality of service (QoS) and have favorable to maximize battery capacity. The resources of queues in IEEE 802.11e networks may be wasted by the transmission of information that is useless to the receiver. This work develops a frame-based mapping mechanism (FBM) that exploits different methods to process I/P/B (Intra/Predictive/Bipredictive) video frame packets. FBM refers to the dropping of arriving packets if the preceding packets in the same video frame have been dropped. When fragmented packets of a single frame are allocated to different access categories (AC) queues, out-of-order delivery may occur. Hence, FBM tries to treat all fragmented packets of each video frame equally and allocates them to the same AC queue if possible. The simulation results demonstrate that transmission by the FBM is more efficient than that by other mechanisms, such as EDCA (Enhanced Distributed Channel Access), static mapping and adaptive mapping, suggesting that the energy of a device is not wasted in the transmission of useless video data in WLANs.

A Burst Effort Broadcasting Approach of MPEG-4 Video Transmission for Intervehicle Communication

Efficient and real-time video broadcasting helps to improve driving safety and to make traveling fun for drivers. However, it is hard to structure vehicles into permanent network topologies and schedules to broadcast video streaming real-time in intervehicle communication (IVC) in a high-mobility vehicular environment. In order to achieve this, we have designed a burst effort broadcasting (BEB) approach for IVC, which considers the challenges of high mobility and multihop broadcast, as well as the features of MPEG-4 video streams to adapt to highway scenarios. The BEB approach is distributed in real time without protocol overhead and comprises a queuing procedure and a scheduling scheme. The queuing procedure consists of the preprocess of video transmission, including the video shaping of groups of pictures and sequential reordering video frames. Based on the queuing procedure, a mobility-adaptive scheduler is applied to handle the broadcast and rebroadcast of the video stream. The concept of macroscopic broadcast is utilized to increase the broadcast performance and the video perceived quality of service (PQoS), and to reduce the number of unnecessary redundant broadcasts. As an evaluation, the real MPEG-4 video was conducted in simulation and the broadcast performance was compared with another protocol by the metrics of peak-signal-to-noise ratio (PSNR) and loss of video frames in different broadcasting scenarios. Then, the results were analyzed. The simulation proved that this approach is an efficient multihop broadcast solution that does indeed provide a realistic solution to promote a higher degree of video PQoS on highways.

Data traffic load balancing and QoS in IEEE 802.11 network: Experimental study of the signal strength effect

The performances of multimedia applications built on wireless systems depend on bandwidth availability that might heavily affect the quality of service. The IEEE 802.11 standards do not provide performed mechanism for bandwidth management through data load distribution among different APs of the network. Then, an AP can be heavily overloaded causing throughput degradation.Load Balancing Algorithms (LBAs) was been considered as one of the attractive solution to share the traffic through the available access points bandwidths. However, applying the load balancing algorithm and shifting a mobile connection from an access point to another without considering the received signal strength indicator of the concerned APs might causes worst communication performances. This paper is a contribution to check the performance’s limits of the LBA algorithm through experimental evaluation of communication metrics for MPEG-4 video transmission over IEEE 802.11 network. Then, the paper focuses on the proposition of a new LBA algorithm structure with the consideration of the RSS level.

A Video Compression Method for Wireless Transmission

With the ever-increasing expansion of wireless voice and data plan demands, bandwidth constrained wireless channels intervened with mobility issues lay out a great challenge in the hardware configuration, software development and algorithm design of communication systems. This paper presents our work on a modular and standards-independent DSP-based testbed designed for real-time video communication over low-bandwidth channels. In particular, the real-time transmission of MPEG-4 video and JPEG2000 still images over the Bluetooth wireless standard is demonstrated here. The testbed was designed to explore the possibilities, demands, and challenges of real-time wireless video transmission. The work could have tremendous near-future applications.

Evaluation on Routing Protocols over MANETs with Fading Channel

Mobile Ad-Hoc networks (MANET) has been getting the spotlight in the area of the wireless networks because of its flexibility and salability, and developing of many applications with it. As a consequence, MANETs are required to process not only simple data traffics, but also multimedia traffics, which has some constraints on the performances. However, unlike wired-networks, the wireless networks have frequent route-disconnections due to some reasons such as channel errors and mobility. Such frequent link disconnections makes the delivery of multimedia traffics difficult. Even though there many researches on multimedia transmissions on various environments, the performances of multimedia transmissions over fading channel and mobility even using various routing protocols have not been evaluated. Therefore, this paper extensively simulates the MPEG-4 video transmission over fading channel environment with node's mobility. In addition, the performances with two routing protocols such as AODV and DSR are compared. Finally, the simulation results shows that DSR protocol has the better performances to deliver MPEG-4 traffic.

A Cross-Layer Approach in Sensing and Resource Allocation for Multimedia Transmission over Cognitive UWB Networks

We propose an MAC centric cross-layer approach to address the problem of multimedia transmission over cognitive Ultra Wideband (C-UWB) networks. Several fundamental design issues, which are related to application (APP), medium access control (MAC), and physical (PHY) layer, are discussed. Although substantial research has been carried out in the PHY layer perspective of cognitive radio system, this paper attempts to extend the existing research paradigm to MAC and APP layers, which can be considered as premature at this time. This paper proposed a cross-layer design that is aware of (a) UWB wireless channel conditions, (b) time slot allocations at the MAC layer, and (c) MPEG-4 video at the APP layer. Two cooperative sensing mechanisms, namely, AND and OR, are analyzed in terms of probability of detection ( ), probability of false alarm ( ), and the required sensing period. Then, the impact of sensing scheduling to the MPEG-4 video transmission over wireless cognitive UWB networks is observed. In addition, we also proposed the packet reception rate- (PRR-) based resource allocation scheme that is aware of the channel condition, target PRR, and queue status.

An adaptive cross-layer mapping algorithm for MPEG-4 video transmission over IEEE 802.11e WLAN

This paper proposes an adaptive cross-layer mapping algorithm to improve the transmission quality of MPEG-4 video stream over an IEEE 802.11e wireless network. Instead of classifying video data to a specific access category in an 802.11e network, we propose an algorithm that dynamically maps MPEG-4 video packets to appropriate access categories according to both the significance of the video data and the network traffic load. Our proposed cross-layer architecture passes information about the significance of video packets from the application layer to the media access control layer. The queue length of a specific access category is used to deduce the network traffic load. We conducted a performance evaluation of our proposed cross-layer approach under both light and heavily loaded network conditions. Our simulation results demonstrate: (a) superior performance of our proposed approach (under both light and heavy loads) over 802.11e (Enhanced Distributed Channel Access (EDCA) and static mapping schemes, (b) not only guarantees prioritized transmission of essential video data but also provides efficient queue length utilization.

An integrated rate control scheme for TCP-friendly MPEG-4 video transmission

Delivering MPEG-4 real-time video over the Internet requires the use of rate control schemes in both the compression and the transport domains. This paper discusses the practical difficulties involved in integrating MPEG-4 scalable rate control (SRC) in the compression domain with TCP-friendly rate control (TFRC) in the transport domain. In addition to the requirement for rate matching between the two schemes to ensure TCP-friendliness, users demand a high-quality, smooth media output under the varying network conditions. In this paper, an integrated rate control scheme is proposed for MPEG-4 video transported by a TFRC protocol. The proposed scheme comprises a rate smoothing control mechanism to meet the rate matching with the controlled transmission buffering delay, and an adaptive rate control for the I-frame designed to reduce the frame skipping. Through the successful integration of the two schemes, the experimental results show that the proposed scheme better preserves the motion smoothness and improves the overall perceptual quality for TCP-friendly MPEG-4 video transmissions to obtain a smooth, high visual quality video experience.

Temporal Error Concealment for MPEG Coded Video Using a Self-Organizing Map

The performance of MPEG video transmission over error-prone channels is limited by the channel noise. An efficient error concealment (EC) scheme is essential for diminishing the impact of transmission errors in a compressed video, A number of EC techniques have been developed to combat the transmission errors. However, the previous techniques are always inefficient when the motions of video object are fast or complex. This paper proposes a novel adaptive EC algorithm to conceal the error for block and motion-compensation based video coding systems. The proposed EC method employs an unsupervised artificial neural network (ANN) model, i.e. self-organizing map (SOM), as a predictor to estimate the motion vectors of the damaged macroblocks (MBs). Then the estimated motion vectors were utilized to reconstruct the damaged MB by exploiting the spatial information from reference frames based on the boundary matching criterion. Because of the SOM has a great capacity for visualizing and interpreting high-dimensional data sets, the estimation model proposed herein can exploit the nonlinearity property of the SOM to estimate lost motion vectors more accurately. Computer simulations show that the visual quality and the PSNR evaluation of reconstructed frames are significantly improved by using the proposed EC algorithm. Thus, the proposed algorithm is expected to be practical for motion vector compressed video in error-prone networks.

A two markers system for improved MPEG video delivery in a DiffServ network

The failure of legacy packet markers such as the Single Rate Three Color Marker (SRTCM) and the Two Rate Three Color Marker (TRTCM) to distinguish important and less important data renders them unsuitable for MPEG video transmission in a DiffServ network. Therefore, we propose a Two Markers System (TMS) to improve the delivery quality of MPEG video streams. We use authentic MPEG4 video traffic traces to compare the performance of the proposed TMS system with those of legacy packet markers. Results show that TMS outperforms the legacy traffic markers in terms of the quality of the delivered MPEG video streams.

A hybrid error concealment scheme for MPEG-2 video transmission based on best neighborhood matching algorithm

For entropy-coded MPEG-2 video frames, a transmission error will not only affect the underlying codeword but also may affect subsequent codewords, resulting in a great degradation of the received video frames. In this study, a hybrid error concealment scheme for MPEG-2 video transmission is proposed. The objective is to recover high-quality MPEG-2 video frames from the corresponding corrupted video frames, without increasing the transmission bit rate. In this study, transmission errors or equivalently corrupted/lost video packets in MPEG-2 video frames are detected and located by the error detection scheme proposed by Shyu and Leou [IEEE Trans. Circuits Syst. Video Technol. 10 (4) (2000) 659], and then the corrupted blocks are concealed by the proposed hybrid error concealment scheme. Based on the fitness function for evaluating the candidate concealed blocks of a corrupted block, a corrupted block in an intra-coded I frame is concealed by either the spatial error concealment algorithm in H.264 or the proposed fast best neighborhood matching (BNM) algorithm. A corrupted block in an inter-coded P or B frame is concealed by the proposed fast motion-compensated BNM algorithm. Based on the simulation results obtained in this study, the proposed scheme can recover high-quality MPEG-2 video frames from the corresponding corrupted video frames up to a packet loss rate of 20%. The performance of the proposed scheme is better than those of four existing approaches for comparison.

A novel scheme for space-time block coding with a variable transmit diversity gain in OFDM systems

A novel scheme for space-time block coding with a variable transmit diversity gain is proposed for OFDM systems in the paper. The OFDM symbols are divided into two groups of orthogonal sub-symbols with each group coded in Alamouli STBC in the coding, and the new scheme for STBC is constructed by differently combining the coded data of each group with the different transmit diversity gain to be achieved by linear processing and correspondingly combining the received data on the sub-carriers. The proposed scheme is feasible to be used in video transmission and a new unequal error protection applied to MPEG-4 video transmission is discussed. The results of computer simulation show that the proposed scheme has double diversity gain and quadruple diversity gain. The new unequal error protection scheme has a gain more than 8 dB and higher efficiency than the UEP based on the RCPC codes.

MPEG-4 Video Transmission over Wireless Networks: A Link Level Performance Study

With the scalability and flexibility of the MPEG-4 and the emergence of the broadband wireless network, wireless multimedia services are foreseen to become deployed in the near future. Transporting MPEG-4 video over the broadband wireless network is expected to be an important component of many emerging multimedia applications. One of the critical issues for multimedia applications is to ensure that the quality-of-service (QoS) requirement to be maintained at an acceptable level. This is further challenged in that such a service guarantee must be achieved under unreliable and time-varying wireless channels. In this paper we study the link level performance of MPEG-4 video transmission over the uplink of an unreliable wireless channel. We introduce the discrete time batch Markovian arrival process (DBMAP) with two types of arrivals to model the MPEG-4 video source, which takes into account the inherent nature of the adaptiveness of the video traffic. We prove that in a hidden Markov modeled (HMM) wireless channel with probabilistic transmission, the service time for an arbitrary radio link control (RLC) burst follows phase type (PH-type) distribution. We show that the link level performance of a wireless video transmission system can be modeled by a DBMAP/PH/1 priority queue, and present computation algorithm and numerical results for the queueing model. Extensive simulations are carried out on the queueing behavior of the video transmission buffer, as well as on the packet level error behavior of the video data. The results demonstrate that video quality can be substantially improved by preserving the high priority video data during the transmission.

Protocol architecture for MPEG-2 video over a high speed network

Real-time communication services related to encoded video transmission over a high-speed network such as ATM need a new integrated protocol architecture to meet the required quality. Data cells are exposed to delays and losses, which affect the video signal quality, and so adequate processing is needed in order to keep the quality of service as an acceptable level. The authors propose the design of a new adaptation of MPEG-2 video in ATM networks in order to improve the video visual quality. The approach, based on a new MPEG-2 protocol architecture, tries to overcome the difficulty imposed by traditional random cell discarding due to the bursty aspect of the traffic and the variable bit rate transmission nature of encoded video. The importance of including a dynamic bandwidth reallocation and appropriate interleaving technique for bursty encoded video traffic being carried in an ATM network is shown, by comparing the degradation quality of an MPEG-2 sequence with and without the proposed techniques. The results show that the proposed interface is effective in solving the cell-loss problem and thus enhances the QoS for MPEG-2 video transmission in ATM networks.

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

Access control for MPEG video applications using neural network and simulated annealing

We present a dynamic modelfor access control mechanism used in computer communication network applied to MPEG video transmission over Internet. This modelis different fromthosedeveloped inthe previous works related to this topic. In our model, token buckets supported by data buffersare used to shape incoming traffic and one multiplexor, serving all the token pools, multiplexes all theconforming traffic. The model is governed by a system of discrete nonlinear difference equations. Weuse neural network as the feedback controller which receives at its input (measurable) available information and provides at its output the optimal control. The simulated annealing algorithm isusedto optimize the system performance by adjusting the weights. For illustration, we presentnumerical results which show that the system performance of MPEG video server can be improved by using neural network and simulated annealing approach.

Joint source-channel decoding for mpeg-4 video transmission over wireless channels

This paper investigates the use of joint source-channel coding for reliable transmission of MPEG-4 video over wireless channels. We present a maximum a posteriori probability (MAP) based, joint source-channel decoder (JSCD) for variable length coded intra macroblocks and inter macroblocks in a MPEG-4 encoded video stream. We then provide a comprehensive evaluation of this paradigm as an alternative method for achieving error resilience. In particular, our method is tested in conjunction with the MPEG-4 error resilience tools such as reversible variable length codes (RVLC), resynchronization markers, and data partitioning, with and without forward error controls (FECs) and, finally, without the use of RVLCs (only variable length codes). In addition, the JSCD algorithm is tested with and without the use of FECs [Reed-Solomon (RS) codes]. These tests show that the best performance at high channel bit-error rate is obtained when all error resilience tools are co-opted. The maximum improvement due to the proposed decoder when used without FEC is about 7 dB for RVLC and 8 dB for VLCs. These numbers are about 2.2 and 7.5 dB, respectively, when the MAP decoder is used in conjunction with the RS codes.

A novel selective motion vector matching algorithm for error concealment in MPEG-4 video transmission over error-prone channels

The performance of MPEG-4 video transmission over error-prone channels is limited by the channel noise. Error concealment is an effective method of combat to these channel errors. In MPEG-4 video coding, motion vectors (MVs) are highly significant for the matching of the missing video block. Thus how to recover the lost MV is an important issue for error concealment in MPEG-4 video communications. Concerning the high block loss ratio (BLR) during video transmission and the matching of edge blocks in video frames, we propose the selective motion vector matching (SMVM) algorithm for MV recovery. It incorporates the status flags of the neighboring pixels of the missing block and constructs new MV sets for block matching. Experimental results show that it is highly effective and significantly outperforms other existing MV recovery methods for error concealment at different BLRs.