Variable-bit-rate HDTV codec with ATM-cell-loss compensation

IEEE Trans. Circuits Syst. Video Technol.

Chang

1999

Video sequences compressed by the current videocompression standards-such as MPEG-1/2 and H.261/H.263, which include motion compensation and variable-length coding-are very sensitive to channel disturbances. There exist many error-concealment techniques that can improve the video quality substantially. However, they generally do not prevent or terminate the error propagation. The forced intraupdate technique was proposed for H.245 recently. In this paper, we present an efficient temporal error-propagation prevention method that implements the forced intraupdate concept implicitly. Once an error is detected at the decoder, the starting address of the erroneous macroblocks is sent back to the encoder. The encoder marks the possible damaged area, and the encoding process continues as normal except that the motion estimation will probably not refer to the erroneous part. Thus, the impact of the cell loss is limited to the erroneous slice only, and the damage from the error propagation is greatly reduced. Simulation results of MPEG-2 coding over asynchronous transfer mode (ATM) networks show that the error concealment with feedback can effectively isolate the error and reduce the damage to give satisfactory performance even when the cell-loss rate is higher than 1%. With the delay analysis of ATM networks, we also show that in most cases, the encoder has adequate time to get the feedback information before processing the next I-or P-frames. Index Terms-Asynchronous transfer mode (ATM), error concealment, error prevention, error propagation, quality of service, video coding. I. INTRODUCTION T HE MOST commonly used video-compression techniques are based on MPEG-1/2 [1]-[3] or H.26x-i.e., H.261 or H.263 [4], [5]-where motion compensation, discrete cosine transform (DCT)-based coding, variable-length coding (VLC), and adaptive quantization are performed. These coding techniques are very sensitive to channel disturbances. A single error may cause error propagation in both spatial and temporal domains. Both MPEG and H.26x streams are constructed by layered structures. In MPEG, a groupof-pictures (GOP) layer generally includes one intrapicture (I-frame), several predicted pictures (P-frames), and several bidirectional predictive pictures (B-frames). The H.26x coding streams may consist of one I-frame and many P-frames or PB-frames. Each picture is further divided into a number of slices, or group of blocks (GOB) in H.26x, of contiguous macroblocks (MB's). A slice is the minimum element that Manuscript

Section: Overview Of the Real-time Video Systemmentioning

confidence: 99%

Error-propagation prevention technique for real-time video transmission over ATM networks

IEEE Trans. Circuits Syst. Video Technol.

Chang

1999

“…A packet often contains data from several blocks. To prevent the loss of contiguous blocks because of a single packet loss, interleaved packetization can be used, by which successive blocks are put into nonadjacent packets [19], [61]. This way, a packet loss will affect blocks in an interleaved order (i.e., a damaged block is surrounded by undamaged blocks), which will ease the error-concealment task at the decoder.…”

Section: G Transport-level Controlmentioning

confidence: 99%

Error control and concealment for video communication: a review

Zhu²

1998

Proc. IEEE

1,143

The problem of error control and concealment in video communication is becoming increasingly important because of the growing interest in video delivery over unreliable channels such as wireless networks and the Internet. This paper reviews the techniques that have been developed for error control and concealment in the past 10-15 years. These techniques are described in three categories according to the roles that the encoder and decoder play in the underlying approaches. Forward error concealment includes methods that add redundancy at the source end to enhance error resilience of the coded bit streams. Error concealment by postprocessing refers to operations at the decoder to recover the damaged areas based on characteristics of image and video signals. Last, interactive error concealment covers techniques that are dependent on a dialogue between the source and destination. Both current research activities and practice in international standards are covered.

“…The compression ratio for an HDTV signal can be from 20:1 to 50:1. Based on a study by Kinoshita et al, 1 the peak rate can be 65Mb/s and average 10 to 20 Mb/s for one HDTV stream transmission in an ATM network. Based on experience with a state highway agency (SHA), the possible number of simultaneous users accessing video and data streams can be as high as 50.…”

Section: Gigabit Local Networking For Mmhismentioning

confidence: 99%

Multimedia Services for Highway Infrastructure Management

Computer aided Civil Eng

1997

Photographic logging systems used by highway agencies provide engineers with information in the analysis of traffic accidents, design improvements, and highway pavement management. However, there exist limitations for such systems in the areas of accessibility, search capability of the image library, and synchronization video data with traditional engineering site data. More important, there are situations in which multiple users may need to examine the video footage at the same time. This capability cannot be provided by current systems. The analog nature of the video signals also presents difficulties in integrating the visual information with other types of data. This paper introduces a type of multimedia service that can be applied in a state highway department environment for highway infrastructure management. This multimedia-based information system utilizes state-of-the-art technologies in digital video, high-speed networking, and video server. This paper discusses the requirements of high-speed networking systems and presents a new computer network that has the potential to become a dominant technology for the transmission of multimedia data. In addition, design concerns regarding the video server and its structure are also discussed. A data-synchronization algorithm is also presented on how to dynamically display digital video frames with traditional engineering data sets that contain information such as as-built data, pavement condition and performance, traffic safety, geometric features, and other infrastructure data.