Video-based Dynamic Mesh Coding (V-DMC) compresses dynamic mesh data by using a low-resolution mesh and displacement data that is added to the subdivided low-resolution mesh at reconstruction. By increasing the number of subdivisions, more displacement data is applied, and higher quality is obtained. However, the number of reconstructed faces becomes larger than the input face count. In an environment with limited computing resources, it is necessary to keep the number of triangles of the reconstructed mesh the same as the one of the original mesh. It is a challenge to achieve high quality while keeping the number of reconstructed faces. This paper describes the edge length-based adaptive subdivision method adopted in V-DMC. This method restricts refinement of small faces by checking edge length of each face. A target number of decoded mesh faces can be reached by setting a threshold. Experimental results show the proposed method provides finer control over the bitrate and quality of the V-DMC stream.

For a V-PCC1system to be able to reconstruct a single instance of the point cloud one V-PCC unit must be transferred to the 3D point cloud reconstruction module. It is however required that all the V-PCC components i.e. occupancy map, geometry, atlas and attribute to be temporally aligned. This, in principle, could pose a challenge since the temporal structures of the decoded sub-bitstreams are not coherent across V-PCC sub-bitstreams. In this paper we propose an output delay adjustment mechanism for the decoded V-PCC sub-bitstreams to provide synchronized V-PCC components input to the point cloud reconstruction module.

In this paper, we describe a robust method for the extraction of the apparent 3-D camera velocity and 3-D scene structure information. Our method performs the extraction of the apparent 3-D camera velocity in a fully automated way without any knowledge about 3-D scene content information as used in current methods. This has the advantage that it can be used to fully automate the generation of natural-looking virtual/augmented environments, as well as in video-database browsing. First, we describe our method for the robust extraction of 3-D parameters. This method is a combination of the eight-point method in structure-from-motion with a statistical technique to automatically select feature points in the image, irrespective of 3-D content information. Second, we discuss two applications which use the results of the 3-D parameter extraction. The first application is the generation of sprite layers using 3-D camera velocity information to represent an eight-parameter perspective image-to-sprite mapping plus 3-D scene depth information for the sprite layering. The second application is the use of 3-D camera velocity for the indexing of large video databases according to a set of seven independent types of camera motion. In this application, we discuss a formal video description structure-the camera-motion descriptor-which was successfully included in the working draft of the MPEG-7 video standard.

We describe the MPEG2 4:2:2 Profile and present a study of its characteristics. The MPEG2 4:2:2 Profile provides a conformance point that addresses, among other applications, the needs of the professional studio and post-production environment, and that provides interoperability. The requirements of such an environment for compressed digital video together with a functional description of the 4:2:2 Profile are given. The 4:2:2 Profile provides a flexible compression solution that allows editability, supports a wide range of bit rates, and provides good to excellent quality in both an intra and interstudio environment. Our experiments show that the 4:2:2 Profile is very robust in a multigeneration environment, provides an efficient coding solution for transmission and storage, and provides transparency or near transparency in chroma keying operations. In addition, it compares favorably with existing digital compression standards, such as Motion-JPEG, and is superior to widely used analog technology.

The authors present a scheme for smoothing delay-sensitive traffic offered to an asynchronous transfer mode (ATM) network. They outline such a smoothing scheme, which, when applied to variable bit rate (VBR) coded video traffic, is both optimal and avoids violation of delay constraints. The scheme is based on the assumption that recent behavior of the traffic stream can be used to predict the behavior of the input stream in the near future. The effectiveness of the scheme was evaluated by simulation. The conclusion is that even with a rudimentary forecasting rule, smoothing can lower cell losses and increase the effectiveness of VBR schemes for video transmission.>

Source modeling and performance issues are studied using a long (30 min) sequence of real video teleconference data. It is found that traffic periodicity can cause different sources with identical statistical characteristics to experience differing cell-loss rates. For a single-stage multiplexer model, some of this source-periodicity effect can be mitigated by appropriate buffer scheduling and one effective scheduling policy is presented. For the sequence analyzed, the number of cells per frame follows a gamma (or negative binomial) distribution. The number of cells per frame is a stationary stochastic process. For traffic studies, neither an autoregressive model of order two nor a two-state Markov chain model is good because they do not model correctly the occurrence of frames with a large number of cells, which are a primary factor in determining cell-loss rates. The order two autoregressive model, however, fits the data well in a statistical sense. A multistate Markov chain model that can be derived from three traffic parameters is sufficiently accurate for use in traffic studies.>

A new method for locating edges in digital data to subpixel values and which is invariant to additive and multiplicative changes in the data is presented. For one-dimensional edge patterns an ideal edge is fit to the data by matching moments. It is shown that the edge location is related to the so-called ``Christoffel numbers.'' Also presented is the study of the effect of additive noise on edge location. The method is extended to include two-dimensional edge patterns where a line equation is derived to locate an edge. This in turn is compared with the standard Hueckel edge operator. An application of the new edge operator as an edge detector is also provided and is compared with Sobel and Hueckel edge detectors in presence and absence of noise.

A method is presented to automatically inspect the block boundaries of a reconstructed two-dimensional transform coded image, to locate blocks which are most likely to contain errors, to approximate the size and type of error in the block, and to eliminate this estimated error from the picture. This method uses redundancy in the source data to provide channel error correction. No additional channel error protection bits or changes to the transmitter are required. It can be used when channel errors are unexpected prior to reception.