Video Transmission Scheme Research Articles

Error resilient texture coding scheme for wireless Video transmission based on coefficient sampling and interleaving

We tackle the problem of burst error in wireless video trans- mission. Burst error damages video information so severely that it is very difficult to restore the lost information. For restoration, it is advantageous to retain a part of block information. To achieve this, we propose a coef- ficient sampling and interleaving method, where texture coefficients are grouped into several coefficient groups CGs so that the groups have equal importance. The CGs are interleaved so that burst error cannot damage all CGs from one block. A restoration method is proposed to utilize the retained coefficients. The simulation results show that the pro- posed coefficient sampling scheme and the restoration method restore the lost information very well. © 2005 Society of Photo-Optical Instrumentation

Adaptive unequal loss protection for scalable video streaming over ip networks

Video streaming over IP networks faces many challenges due to the varying network conditions such as time-varying packet loss and fluctuating bandwidth. In this paper, we focus on streaming scalable video over IP networks in order to enhance the received video quality. We present an adaptive video transmission scheme, which combines unequal loss protection and layer selecting. In this scheme, we estimate the packet loss effects on video quality using model-based distortion estimation approach, both for the base layer and the enhancement layers. Based the estimated distortion, the scheme adaptively assigns the unequal amount of forward error correction to each layer and adjusts the sending rate by dynamically selecting the appropriate number of layers to transmit, according to the packet loss rate and the available network bandwidth. The scheme can provide a graceful degradation of received video quality as packet loss increasing and available bandwidth decreasing. Simulations results show that our scheme can provide reasonable video quality under varying network conditions.

An unequal packet loss resilience scheme for video over the Internet

We present an unequal packet loss resilience scheme for robust transmission of video over the Internet. By jointly exploiting the unequal importance existing in different levels of syntax hierarchy in video coding schemes, GOP-level and Resynchronization-packet-level Integrated Protection (GRIP) is designed for joint unequal loss protection (ULP) in these two levels using forward error correction (FEC) across packets. Two algorithms are developed to achieve efficient FEC assignment for the proposed GRIP framework: a model-based FEC assignment algorithm and a heuristic FEC assignment algorithm. The model-based FEC assignment algorithm is to achieve optimal allocation of FEC codes based on a simple but effective performance metric, namely distortion-weighted expected length of error propagation, which is adopted to quantify the temporal propagation effect of packet loss on video quality degradation. The heuristic FEC assignment algorithm aims at providing a much simpler yet effective FEC assignment with little computational complexity. The proposed GRIP together with any of the two developed FEC assignment algorithms demonstrates strong robustness against burst packet losses with adaptation to different channel status.

Joint source coding and packet classification for real-time video transmission over differentiated services networks

Differentiated Services (DiffServ) is one of the leading architectures for providing quality of service in the Internet. We propose a scheme for real-time video transmission over a DiffServ network that jointly considers video source coding, packet classification, and error concealment within a framework of cost-distortion optimization. The selections of encoding parameters and packet classification are both used to manage end-to-end delay variations and packet losses within the network. We present two dual formulations of the proposed scheme: the minimum distortion problem, in which the objective is to minimize the end-to-end distortion subject to cost and delay constraints, and the minimum cost problem, which minimizes the total cost subject to end-to-end distortion and delay constraints. A solution to these problems using Lagrangian relaxation and dynamic programming is given. Simulation results demonstrate the advantage of jointly adapting the source coding and packet classification in DiffServ networks.

A fuzzy control scheme for video transmission in Bluetooth wireless

This paper is concerned with transmission of Moving Picture Expert Group (MPEG) video over a Bluetooth wireless network using a fuzzy approach. MPEG Variable Bit Rate (VBR) video sources suffer from long delay and excessive loss due to the sudden bursts in bit rate. Constant Bit Rate (CBR) encoding scheme may work well for a network with a guaranteed bandwidth. However, a Bluetooth channel is subject to wireless interference and can never guarantee a constant bandwidth. Subsequently, it is impossible to transmit a CBR video over Bluetooth wireless without data loss or image quality degradation. To resolve this problem, a fuzzy control system is introduced at the Host Controller Interface (HCI). The system consists of a traffic-shaping buffer whose role is to prevent excessive back-to-back cells being generated during the peak transmissions of MPEG video sources. The output bit rate of the traffic-shaping buffer is controlled by a fuzzy controller to ensure that the video stream from the host conforms to the traffic condition of the Bluetooth channel. Another fuzzy controller regulates the average arrival bit rate to the traffic-shaper to guarantee that the buffer is neither full nor empty. Computer simulation results demonstrate that the use of the fuzzy controllers reduces excessive data loss at the HCI as compared with an open loop VBR/CBR video transmission in Bluetooth.

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.

Optimal resource allocation for wireless video over CDMA networks

We present a multiple-channel video transmission scheme in wireless CDMA networks over multipath fading channels. We map an embedded video bitstream, which is encoded into multiple independently decodable layers by 3D-ESCOT video coding technique, to multiple CDMA channels. One video source layer is transmitted over one CDMA channel. Each video source layer is protected by a product channel code structure. A product channel code is obtained by the combination of a row code based on rate compatible punctured convolutional code (RCPC) with cyclic redundancy check (CRC) error detection and a source-channel column code, i.e., systematic rate-compatible Reed-Solomon (RS) style erasure code. For a given budget on the available bandwidth and total transmit power, the transmitter determines the optimal power allocations and the optimal transmission rates among multiple CDMA channels, as well as the optimal product channel code rate allocation, i.e., the optimal unequal Reed-Solomon code source/parity rate allocations and the optimal RCPC rate protection for each channel. In formulating such an optimization problem, we make use of results on the large-system CDMA performance for various multiuser receivers in multipath fading channels. The channel is modeled as the concatenation of wireless BER channel and a wireline packet erasure channel with a fixed packet loss probability. By solving the optimization problem, we obtain the optimal power level allocation and the optimal transmission rate allocation over multiple CDMA channels. For each CDMA channel, we also employ a fast joint source-channel coding algorithm to obtain the optimal product channel code structure. Simulation results show that the proposed framework allows the video quality to degrade gracefully as the fading worsens or the bandwidth decreases, and it offers improved video quality at the receiver.

VBR video transmission with isochronous and asynchronous transfer mode over wireless 1394

AbstractWe propose a VBR video transmission scheme with isochronous and asynchronous transfer mode over Wireless 1394. In the proposed scheme, to decrease the idle bandwidth in the isochronous area, a video station which uses the isochronous transfer mode is assigned bandwidth equivalent to the average rate of the video stream. Video data over the average rate are transmitted in asynchronous transfer mode, and video stations have higher transmission priority than data stations in asynchronous transfer mode. By computer simulations, we show that the proposed scheme can improve the channel utilization performance and the waiting time performance, and that it is effective for VBR video transmission. © 2004 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 88(4): 64–74, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.10233

An Integrated Source and Channel Rate Allocation Scheme for Robust Video Coding and Transmission over Wireless Channels

A new integrated framework for source and channel rate allocation is presented for video coding and transmission over wireless channels without feedback channels available. For a fixed total channel bit rate and a finite number of channel coding rates, the proposed scheme can obtain the near-optimal source and channel coding pair, and corresponding robust video coding scheme such that the expected end-to-end distortion of video signals can be minimized. With the assumption that the encoder has the stochastic information such as average SNR and Doppler frequency of the wireless channel, the proposed scheme takes into account robust video coding, channel coding, packetization, and error concealment techniques altogether. An improved method is proposed to recursively estimate the end-to-end distortion of video coding for transmission over error-prone channels. The proposed estimation is about 1-3 dB more accurate compared to the existing integer-pel based method. Rate-distortion optimized video coding is employed for the trade-off between coding efficiency and robustness to transmission errors.

Interactive Video Coding and Transmission over Heterogeneous Wired-to-Wireless IP Networks Using an Edge Proxy

Digital video delivered over wired-to-wireless networks is expected to suffer quality degradation from both packet loss and bit errors in the payload. In this paper, the quality degradation due to packet loss and bit errors in the payload are quantitatively evaluated and their effects are assessed. We propose the use of a concatenated forward error correction (FEC) coding scheme employing Reed-Solomon (RS) codes and rate-compatible punctured convolutional (RCPC) codes to protect the video data from packet loss and bit errors, respectively. Furthermore, the performance of a joint source-channel coding (JSCC) approach employing this concatenated FEC coding scheme for video transmission is studied. Finally, we describe an improved end-to-end architecture using an edge proxy in a mobile support station to implement differential error protection for the corresponding channel impairments expected on the two networks. Results indicate that with an appropriate JSCC approach and the use of an edge proxy, FEC-based error-control techniques together with passive error-recovery techniques can significantly improve the effective video throughput and lead to acceptable video delivery quality over time-varying heterogeneous wired-to-wireless IP networks.

A light weight dynamic rate control scheme for video transmission over IP network

This paper proposes a lightweight dynamic rate control strategy for improving the quality of video transmitted over the internet. The proposed scheme includes a feedback mechanism from the receiver to the sender with periodic updates of packet drops. This information is used by the sender to estimate the congestion present in the network and to adjust the transmission rate to avoid further bottlenecks. A mathematical model that relates the three parameters: data rate, congestion present in the network and packet drops has been developed. Experiments were performed on a network consisting of several network elements to validate the model. Results indicate that the proposed dynamic control strategy improves the quality of video over IP networks.

Transform domain inter-block interleaving schemes for robust image and video transmission in ATM networks

Data interleaving schemes have proven to be an important mechanism in reducing the impact of correlated network errors on image/video transmission. Current interleaving schemes fall into two main categories: (a) schemes that interleave pixel intensity values and (b) schemes that interleave JPEG/MPEG transform blocks. The schemes in the first category suffer in terms of lower compression ratio since highly correlated information in the spatial domain is de-correlated prior to compression. The schemes in the second category interleave DCT transformed blocks. In this case, in the absence of ARQ, if a packet is lost, an entire block may be lost thus yielding poor image quality and making the error concealment task difficult. Interleaving transform coefficients is tricky and error concealment in the presence of lost coefficients is challenging. In this paper, we develop three different interleaving schemes, namely Triangular, Quadrant, and Coefficient, that interleave frequency domain transform coefficients. The transform coefficients within each block are divided into small groups and groups are interleaved with the groups from other blocks in the image, hence they are referred to as inter-block interleaving schemes. The proposed schemes differ in terms of group size. In the Triangular interleaving scheme AC coefficients in each block are divided into two triangles and interleaving is performed among triangles from different blocks. In the Quadrant interleaving scheme, coefficients in each block are divided into four quadrants and quadrants are interleaved. In the Coefficient interleaving scheme, each coefficient in a block is a group and it is interleaved with the coefficients in other blocks. The compression ratio 3 of the proposed interleaving schemes is impressive ranging from 90 to 98% of the JPEG standard compression while providing much higher robustness in the presence of correlated losses. We also propose two new variable end-of-block (VEOB) techniques, one based on the number of AC coefficients per block (VAC-EOB) and the other based on the number of bits per block (VB–EOB). Our proposed interleaving techniques combined with VEOB schemes yield significantly better compression ratios compared to JPEG (2–11%) and MPEG-2 (3–6.7%) standards while at the same time improve the resilience of the coded data in the presence of transmission errors.

A combined multiple-candidate likelihood decoding and error concealment scheme for compressed video transmission over noisy channels

This paper presents a joint forward error correction (FEC) and error concealment (EC) scheme to enhance the quality of a compressed video signal transmitted over a noisy channel. A multiple candidate likelihood (MCL) channel decoding strategy is used in conjunction with redundancy in the compressed video (syntax validity and spatial discontinuity) to select the best-detected signal. Simulation results on both objective and subjective performance measures indicate a significant improvement provided by the proposed scheme.

A rate adaptation transcoding scheme for real-time video transmission over wireless channels

In this work, we investigate the problem of bit-rate adaptation transcoding for transmitting video over burst-error wireless channels, i.e., channels such that errors tend to occur in clusters during fading periods. In particular, we consider a scenario consisting of packet-based transmission with an Automatic Repeat reQuest (ARQ) error control and a feedback channel. With the acknowledgements received through the feedback channel and a statistical channel model, we have an estimate of the current channel state, and effective channel bandwidth. In this paper, we analyze the buffering implications of inserting a video transcoder at the wireless access point with the variable bit-rate channel as the target. We derive the conditions that both the source encoder and transcoder buffers have to meet for preventing the end decoder buffer from underflowing. Furthermore, we propose a bit-rate adaptation algorithm for VBR transcoders used in the wireless access point. Our experimental results demonstrate that the proposed algorithm can accurately control the bit-rate of the transcoded video stream and reduce the number of frames been skipped without violating the end-to-end delay requirement.

Optimal FEC assignment for scalable video transmission over burst error channel with loss rate feedback

This article aims to find an optimal FEC assignment scheme for scalable video transmission over burst error channel with loss rate feedback. In order to apply the loss rate feedback information to further enhance the received video quality, an iterative algorithm has been derived to calculate a new loss probability function, which is conditioned on the past loss rates. In addition, both the complete and the efficient versions of the analytical models about FEC performance in scalable video stream are formulated in this work. Simulation results reveal that our transmission scheme can react to the worse channel condition with less and smoother quality degradation.

A flat, multiscalable, highly efficient and reliable video transmission scheme

AbstractThe transmission of video materials by digital compression has been widely applied in recent years. The following problems are involved in this approach. (1) A duplex system composed of main and backup links is often used in the transmission of video materials. Thus, the transmission capacity of the backup system becomes redundant in the normal state. (2) No automatic image quality monitoring method for video transmission has been established. On the other hand, the coding/decoding techniques for digital video transmission are almost fully established, and various devices are already widely used. Thus, it is highly desirable to reduce the above redundancy, that is, to achieve highly efficient automatic picture quality monitoring. Consequently, this paper proposes a flat multiscalable video transmission scheme in which highly efficient and highly reliable video transmission with automatic picture quality monitoring can be realized by simply adding pre‐ and postprocessing, without modifying the existing coding/decoding devices. In the proposed scheme, noise cancellation by averaging and high picture quality are realized by processing that reduces the correlation of coding noise in the decoded video pictures of the two systems. The SN ratios of the received video and the original pictures can be estimated from the residual correlation. The proposed scheme can be applied not only to improving the efficiency of video materials transmission, but also to improving the reliability of picture transmission over the Internet. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 86(7): 42–53, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.1168

Robust H.263+ video transmission using partial backward decodable bit stream (PBDBS)

We propose a novel robust H.263+ video transmission scheme using a partial backward decodable bit stream (PBDBS), which reverses the bit stream of some coded macroblocks (MBs) so that these coded MBs can be decoded in a backward direction. Because of using variable-length coding (VLC), the baseline H.263+ coder will lose synchronization until the next resynchronization marker when errors occur in the coded bit stream. It is wasteful to discard all of the remaining coded MBs in a group of blocks (GOB). Our method is to alleviate this effect by reversing the bitstream that belongs to the coded second half row of MBs in a GOB. When a decoder loses resynchronization, it will search the next resynchronization marker and decode the bitstream backward. It can retrieve half row of MBs that are lost otherwise. This method combined with error concealment can greatly improve the transmitted image quality. Up to 2-dB luminance peak signal-to-noise ratio improvement can be found in our method compared with the baseline H.263+ coder. We also compare our PBDBS method with H.263++ Annex V using data partitioning and reversible VLC. Under lower encoder and decoder complexity, the PBDBS method obtains more pleasant results than Annex V, and it can be utilized in noisy channels such as wireless networks.

An efficient motion compensation algorithm based on double reference frame method

Abstract Recently, several techniques based on the multiple reference frame scheme (Proceedings of the Dada Compression Conference, March 1998, pp. 239–248; Proceedings of the European Signal Processing Conference, September 1998, pp. 253–256; Proceedings of the International Symposium on Information Theory, August 1998, pp. 409–418; IEEE Trans. Circuits Systems Video Technol. 9(1) (February 1999) 70–84; Proceedings of the IEEE International Conference on Image Processing, October 1997, pp. 17–20) have been proposed to improve the motion prediction gain. Though these techniques yield higher prediction gain than the single reference frame scheme, they cannot maintain acceptable image quality at very low bitrate. Besides, the blocking artifacts may be visible along the block boundaries, since each block is predicted independently of its neighbors. And they require tremendous computational complexity for the motion search. To overcome these drawbacks, this paper proposes a novel motion compensation algorithm, based on the double reference frame, the double motion vector, and the searching position shifting (SPS) schemes. First, to reduce the motion vector bitrate and the computational complexity of motion search, we constrain the number of reference frames to 2, and use only two motion vectors per block. Second, to alleviate the blocking artifacts and to yield better prediction performance, the SPS scheme is introduced. Experimental results demonstrate that the proposed algorithm yields about 3– 4 dB higher prediction gain than the single reference frame scheme. Subjective quality is also improved by alleviating the blocking artifacts. In addition, the proposed algorithm can be combined with a robust video transmission scheme. Thus, even if the channel experiences errors during the transmission, the proposed algorithm can efficiently protect the image quality.

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.

Combined source-channel coding schemes for video transmission over an additive white Gaussian noise channel

There has been an increased interest in the transmission of digital video over real-world transmission media, such as the direct broadcast satellite (DBS) channel. Video transmitted over such a channel is subject to degradation due, in part, to additive white Gaussian noise (AWGN). Some form of forward error-control (FEC) coding may be applied in order to reduce the effect of the noise on the transmitted bitstream; however, determination of the appropriate level of FEC coding is generally an unwieldy and computationally intensive problem, as it may depend upon a variety of parameters such as the type of video, the available bandwidth, and the channel SNR. More specifically, a combined source-channel coding approach is necessary in optimally allocating rate between source and channel coding subject to a fixed constraint on overall transmission bandwidth. In this paper we develop a method of optimal bit allocation under the assumption that the distortion is additive and independent on a frame-by-frame basis. A set of universal operational distortion-rate characteristics is developed which balances the tradeoff between source coding accuracy and channel error protection for a fixed overall transmission rate and provides the basis for the optimal bit allocation approach. The results for specific source and channel coding schemes show marked improvement over suboptimum choices of channel error protection. In addition, we show that our results approach information-theoretic performance bounds which are developed in this work.