共查询到20条相似文献,搜索用时 31 毫秒
1.
本文提出了一套针对MPEG-2视频压缩数据传输的自适应容错机制,用于支持地面数字电视广播系统中的可靠电视传输.具体地,本文首先提出了一种基于时域隐藏和块匹配的差错隐藏算法,在保持较好隐藏效果的同时,通过有效地减小搜索窗口而显著降低了算法复杂度.同时,针对独立I帧图像还提出了独特的差错隐藏方法.将这两种差错隐藏算法与低运算复杂度的空域/时域运动检测方法相结合,又衍生出一种自适应空/时域结合差错隐藏算法.仿真结果表明,本文提出的算法即使在很高的数据差错率情况下,仍然可以实现地面数字电视广播系统中可靠而高效的视频传输. 相似文献
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Zi-Wei Zheng Zhi-Xing Yang Chang-Yong Pan Yi-Sheng Zhu 《Broadcasting, IEEE Transactions on》2004,50(2):148-153
As an effective technique for combating multipath fading and for high-bit-rate transmission over wireless channels, orthogonal frequency-division multiplexing (OFDM) is extensively used in modern digital television terrestrial broadcasting (DTTB) systems to support high performance bandwidth-efficient multimedia services. In this paper, novel synchronization schemes, including timing, frequency offset estimation, and phase error tracking, are proposed for the time domain synchronous OFDM (TDS-OFDM) based DTTB systems. Simulations under different channel situations verify the efficiency of the proposed schemes. 相似文献
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Zi-Wei Zheng Zhi-Xing Yang Chang-Yong Pan Yi-Sheng Zhu 《Broadcasting, IEEE Transactions on》2005,51(2):237-243
As an effective technique for combating multipath fading and for high-bit-rate transmission over wireless channels, orthogonal frequency-division multiplexing (OFDM) is extensively used in modern digital television terrestrial broadcasting (DTTB) systems, such as the cyclic prefix OFDM (CP-OFDM) based DVB-T DTTB systems and the time domain synchronous OFDM (TDS-OFDM) based DMB-T DTTB systems, to support high performance bandwidth-efficient multimedia services. OFDM-based DTTB systems are very sensitive to the nonlinear distortion at the transmitter and the imperfect parameters estimation at the receiver. In this paper, the combined effects of nonlinear distortion and imperfect parameters estimation on the performance of the OFDM-based DTTB systems are investigated, a closed form of symbol error probability of the OFDM-based DTTB systems with nonlinear distortion and imperfect parameters estimation is derived. Theoretical results show closely matching with those obtained by simulations for both the CP-OFDM based DVB-T DTTB systems and the TDS-OFDM based DMB-T DTTB systems. 相似文献
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Sung Kyu Jang Jong Beom Ra 《Journal of Visual Communication and Image Representation》2003,14(4):526-542
We propose a modified motion estimation algorithm that is adequate for error localization and temporal error concealment in transmitting videos over unreliable channels. In order to achieve good error concealment performance, the proposed algorithm implicitly imposes spatial correlations on motion vectors by extending the block size and overlapping blocks in motion estimation. Thereby, the obtained motion vectors can be used to improve error concealment performance while keeping the encoding efficiency with negligible overhead. In addition, the proposed motion estimation can provide a new error detection measure so that we can maximally utilize uncorrupted data rather than simply discarding all data in a defected packet. Simulation results show that the proposed motion estimation scheme provides significant improvements in error concealment performance over the existing schemes and improves the bit utility over a wide range of error conditions. 相似文献
5.
Xinguang Xiang Debin Zhao Qiang Wang Siwei Ma Wen Gao 《Journal of Visual Communication and Image Representation》2010,21(8):975-985
Stereoscopic video coding (SSVC) plays an important role in various 3D video applications. In SSVC, robust stereoscopic video transmission over error-prone networks is still a challenge problem to be solved. In this paper, we propose a joint encoder–decoder error control framework for SSVC, where error-resilient source coding, transmission network conditions, and error concealment scheme are jointly considered to achieve better error robustness performance. The proposed joint encoder–decoder error control framework includes two parts: an error concealment algorithm at the decoder side and a rate–distortion optimized error resilience algorithm at the encoder side. For error concealment at the decoder side, an overlapped block motion and disparity compensation based error concealment scheme is proposed to adaptively utilize inter-view correlations and temporal correlations. For error resilience at the encoder side, first, the inter-view refreshment is proposed for SSVC to suppress error propagations. Then, an end-to-end distortion model for SSVC is derived, which jointly considers the transmission network conditions, inter-view refreshment, and error concealment tools at the decoder side. Finally, based on the derived end-to-end distortion model, the rate–distortion optimized error resilience algorithm is presented to adaptively select inter-view, inter- or intra-coding for SSVC. The experimental results show that the proposed joint encoder–decoder error control framework has superior error robustness performance for stereoscopic video transmission over error-prone networks. 相似文献
6.
Packet video error concealment with Gaussian mixture models. 总被引:1,自引:0,他引:1
Daniel Persson Thomas Eriksson Per Hedelin 《IEEE transactions on image processing》2008,17(2):145-154
In this paper, Gaussian mixture modeling is applied to error concealment for block-based packet video. A Gaussian mixture model for video data is obtained offline and is thereafter utilized online in order to restore lost blocks from spatial and temporal surrounding information. We propose estimators on closed form for missing data in the case of varying available neighboring contexts. Our error concealment strategy increases peak signal-to-noise ratio compared to previously proposed schemes. Examples of improved subjective visual quality by means of the proposed method are also supplied. 相似文献
7.
Robust Frame Synchronization for Chinese DTTB System 总被引:3,自引:0,他引:3
Shigang Tang Kewu Peng Ke Gong Jian Song Changyong Pan Zhixing Yang 《Broadcasting, IEEE Transactions on》2008,54(1):152-158
Digital terrestrial multimedia/television broadcasting (DTMB), which is the recently released Chinese digital television terrestrial broadcasting (DTTB) standard, uses guard intervals padded with known pseudo-noise (PN) sequences for multi-carrier or single-carrier block transmission. Well designed synchronization algorithms are a prerequisite for achieving high-quality multimedia transmission. In this paper, a novel frame synchronization technique, which is robust to carrier frequency offset (CFO), is proposed for DTMB systems. This technique is derived through segmenting the local PN sequence into M contiguous blocks and performing multiple cross-correlations with the received signal. The metric for peak detection is defined as the non-coherent summation of the M cross-correlation magnitude outputs. Moreover, a low-complexity frame synchronizer based on segment-based full correlation for PN420 mode in DTMB system is proposed. It is shown through computer simulation that the proposed techniques generally outperform the conventional ones when CFO occurs, over both AWGN and frequency-selective fading channels. For a DTMB system using PN420 mode, the maximal allowed CFO to keep system still working normally of our proposed schemes are more than 3 times larger than that of the conventional method. 相似文献
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A survey of packet loss recovery techniques for streaming audio 总被引:4,自引:0,他引:4
We survey a number of packet loss recovery techniques for streaming audio applications operating using IP multicast. We begin with a discussion of the loss and delay characteristics of an IP multicast channel, and from this show the need for packet loss recovery. Recovery techniques may be divided into two classes: sender- and receiver-based. We compare and contrast several sender-based recovery schemes: forward error correction (both media-specific and media-independent), interleaving, and retransmission. In addition, a number of error concealment schemes are discussed. We conclude with a series of recommendations for repair schemes to be used based on application requirements and network conditions 相似文献
10.
Kwanwoong Song Taeyoung Chung Yunje Oh Chang-Su Kim 《Journal of Visual Communication and Image Representation》2009,20(4):281-292
An efficient error concealment algorithm for multi-view video sequences is proposed in this work. First, we develop three concealment modes: temporal bilateral error concealment (TBEC), inter-view bilateral error concealment (IBEC), and multi-hypothesis error concealment (MHEC). TBEC and IBEC, respectively, exploit intra-view and inter-view correlations in multi-view video sequences to reconstruct an erroneous block. MHEC finds a few candidate blocks based on the block matching principle and combines them for the concealment. We then propose a mode selection scheme, which chooses one of the three modes adaptively to provide reliable and accurate concealment results. Simulation results demonstrate that the proposed algorithm can protect the quality of reconstructed videos effectively even in severe error conditions. 相似文献
11.
《Signal Processing: Image Communication》2014,29(1):37-48
Unequal error protection schemes applied on video data streams, considering varying importance of data packets over a group of pictures (GOP), are more efficient in terms of rate-distortion performance at different loss rates. Importance ordering policy adopted so far, mostly considered frame positions within a GOP. In the present work, we offer significant importance to the packets containing scene-transition frames, as these should be better error protected. We adopt a strategy of Forward Error Correcting (FEC) Code allocation, based on the minimization of end-to-end distortion up to the decoder, assuming that error concealment is adopted at the decoder. Two FEC allocation strategies are proposed within the Block of Packets (BOP) structure — one is an iterative modified hill climbing approach and the other is a reduced complexity heuristic approach. The Gilbert–Elliot model is used for the modeling of transmission channel. The proposed FEC allocation schemes outperform existing FEC allocation schemes in terms of PSNR for sequences with and without transitions, when transmitted over lossy channels. 相似文献
12.
《Broadcasting, IEEE Transactions on》2009,55(3):668-673
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为提高视频通信质量,有多种差错控制方法,其中选择性重传,是一种解决分组丢失问题的有效方法。视频信号传输的选择性重传方法,即基于决策位置、基于优先级、基于网络状态和基于不同层面的选择重传算法,都可以提高视频传输质量。针对不同分类方法讨论现有的各种选择重传方案,实现差错控制的目的。 相似文献
15.
Rogelio Hasimoto-Beltrn Shahab Baqai Ashfaq Khokhar 《Journal of Visual Communication and Image Representation》2004,15(4):69
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. 相似文献
16.
A Gaussian mixture model (GMM)-based spatio-temporal error concealment approach has recently been proposed for packet video. The method improves peak signal-to-noise ratio (PSNR) compared to several famous error concealment methods, and it is asymptotically optimal when the number of mixture components goes to infinity. There are also drawbacks, however. The estimator has high online computational complexity, which implies that fewer surrounding pixels to the lost area than desired are used for error concealment. Moreover, GMM parameters are estimated without considering maximization of the error concealment PSNR. In this paper, we propose a mixture-based estimator and a least squares approach for solving the spatio-temporal error concealment problem. Compared to the GMM scheme, the new method may base error concealment on more surrounding pixels to the loss, while maintaining low computational complexity, and model parameters are found by an algorithm that increases PSNR in each iteration. The proposed method outperforms the GMM-based scheme in terms of computation-performance tradeoff. 相似文献
17.
Huifang Sun Joel W. Zdepski Wilson Kwok D. Raychaudhuri 《Signal Processing: Image Communication》1997,10(4):249-268
This paper provides some research results on the topic of error resilience for robust decoding of MPEG (Moving Picture Experts Group) compressed video. It introduces and characterizes the performance of a general class of error concealment algorithms. Such receiver-based error concealment techniques are essential for many practical video transmission scenarios such as terrestrial HDTV broadcasting, packet network based teleconferencing/multimedia, and digital SDTV/HDTV delivery via ATM (asynchronous transfer mode). Error concealment is intended to ameliorate the impact of channel impairments (i.e., bit-errors in noisy channels, or cell-loss in ATM networks) by utilizing available picture redundancy to provide a subjectively acceptable rendition of affected picture regions. The concealment process must be supported by an appropriate transport format which helps to identify image pixel regions which correspond to lost or damaged data. Once the image regions (i.e., macroblocks, slices, etc.) to be concealed are identified, a combination of spatial and temporal replacement techniques may be applied to fill in lost picture elements. A specific class of spatio-temporal error concealment algorithms for MPEG video is described and alternative realizations are compared via detailed end-to-end simulations for both one- or two-tier transmission media. Several algorithm enhancements based on directional interpolation, ‘I-picture motion vectors’, and use of MPEG-2 ‘scalability’ features are also presented. In each case, achievable performance improvements are estimated via simulation. Overall, these results demonstrate that the proposed class of error concealment algorithms provides significant robustness for MPEG video delivery in the presence of channel impairments, permitting useful operation at ATM cell-loss rates in the region of 10−4 to 10−3 and 10−2 to 10−1 for one- and two-tier transmission scenarios, respectively. 相似文献
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Weerackody V. Reichl W. Potamianos A. 《Wireless Communications, IEEE Transactions on》2002,1(2):282-291
Future wireless multimedia terminals will have a variety of applications that require speech recognition capabilities. We consider a robust distributed speech recognition system where representative parameters of the speech signal are extracted at the wireless terminal and transmitted to a centralized automatic speech recognition (ASR) server. We propose two unequal error protection schemes for the ASR bit stream and demonstrate the satisfactory performance of these schemes for typical wireless cellular channels. In addition, a "soft-feature" error concealment strategy is introduced at the ASR server that uses "soft-outputs" from the channel decoder to compute the marginal distribution of only the reliable features during likelihood computation at the speech recognizer. This soft-feature error concealment technique reduces the ASR error rate by more than a factor of 2.5 for certain channels. Also considered is a channel decoding technique with source information that improves ASR performance 相似文献
20.
Joohee Kim Mersereau R.M. Altunbasak Y. 《IEEE transactions on image processing》2004,13(12):1547-1553
This paper presents a coordinated multiple-substream unequal error-protection and error-concealment algorithm for SPIHT-coded bitstreams transmitted over lossy channels. In the proposed scheme, we divide the video sequence corresponding to a group of pictures into two subsequences and independently encode each subsequence using a three-dimensional SPIHT algorithm. We use two different partitioning schemes to generate the substreams, each of which offers some advantages under the appropriate channel condition. Each substream is protected by an FEC-based unequal error-protection algorithm, which assigns unequal forward error correction codes to each bit plane. Any information that is lost during the transmission for any substream is estimated at the receiver by using the correlation between the substreams and the smoothness of the video signal. Simulation results show that the proposed multiple-substream UEP algorithm is simple, fast, and robust in hostile network conditions, and that the proposed error-concealment algorithm can achieve 2-3-dB PSNR gain over the case when error concealment is not used at high packet-loss rates. 相似文献