In this article, a survey of the point cloud compression (PCC) methods by organizing them with respect to the data structure, coding representation space, and prediction strategies is presented. Two paramount families of approaches reported in the literature-the projection- and octree-based methods-are proven to be efficient for encoding dense and sparse point clouds, respectively. These approaches are the pillars on which the Moving Picture Experts Group Committee developed two PCC standards published as final international standards in 2020 and early 2021, respectively, under the names: video-based PCC and geometry-based PCC. After surveying the current approaches for PCC, the technologies underlying the two standards are described in detail from an encoder perspective, providing guidance for potential standard implementors. In addition, experiment evaluations in terms of compression performances for both solutions are provided.

In this paper, an efficient motion estimation method for quadtree plus binary tree (QTBT) structure is presented for JVET future video coding (FVC). To exploit the possibility to design a new coding standard better than HEVC, an activity called future video coding has been active in MPEG and VCEG. One of the most influential new technologies proposed for FVC is QTBT structure, which can give more flexibility on the prediction block than quadtree-based HEVC. To advance the compression efficiency of QTBT, we propose a method that, for accurate motion estimation, sets a new point and adjusts search range accordingly based on the motion information of parent node. Performance evaluation was conducted on top of joint exploration model (JEM 3.0), which resulted in a 0.41% gain on average in terms of BD-rate under random access scenario without any burden on encoder complexity.

This paper proposes a color attribute compression method for MPEG Point Cloud Compression (PCC) by exploiting the spatial redundancy among the adjacent points. With the increased interest in representing real-world surface as 3D point clouds, compressing the attributes (i.e., colors and normal directions) of point cloud has attracted great attention in MPEG. The proposed method is based on grouping the adjacent points in blocks. And two encoding modes are supported for each block, which include the run-length encoding mode and palette mode. The final encoding mode for each block is determined through comparing two distortion values based on two encoding modes. Experimental results show that the proposed approach achieves about 28 percent compression ratio than that of MPEG PCC.

This correspondence is to address the corrections to the published paper titled "An efficient adaptive binary arithmetic coder based on logarithmic domain".

The latest video coding standards, including Moving Picture Experts Group‐4 (MPEG‐4) advanced video coding (AVC)/H.264 and high‐efficiency video coding (HEVC), use a discrete cosine transform (DCT) process as the core for compression efficiency, sacrificing the computational complexity at decoder. There have been a number of attempts to reduce the complexity of inverse DCT (IDCT). Butterfly‐based factorisation remains the most commonly used method for such a reduction. In this study, the authors propose a zero (Z) coefficient‐aware fast butterfly‐based IDCT algorithm for video decoding. They focus on a reduction in the computational complexity of the butterfly‐based 8 × 8 IDCT by removing the unnecessary computations of one‐dimensional (1D) IDCT kernels, and adaptively applying IDCT kernels based on the number of non‐Z DCT coefficients to speed‐up 1D data. Their experimental results show that the average operation numbers using the proposed IDCT is approximately half that for the 8 × 8 IDCT implemented in the MPEG‐4 AVC/H.264 and HEVC reference software. The improved computational complexity of the proposed method is demonstrated by measuring the running time, which requires only one‐half of the IDCT time using the reference software.

The latest video coding standard, MPEG-4 AVC/H.264 provides the best performance in compression efficiency among existing video coding standards. To achieve higher compression efficiency, AVC/H.264 standard employs a variety of encoding tools but at the expense of greater computational complexity of the encoder. In this paper, we propose a fast mode decision algorithm for the design of a fast AVC/H.264 encoder by exploiting spatio-temporal correlation of macro block (MB) mode types. Through the statistical analysis of encoding mode types in AVC/H.264 JM 11.0, we found that the best mode type of the current MB is highly correlated with the mode types of spatially neighboring MBs and temporally collocated MBs. The experimental results showed that AVC/H.264 encoder using our proposed method produced about 66 % speedup without noticeable visual degradation compared to the AVC/H.264 JM 11.0 encoder.

In this paper, we provide an overview of the reconfigurable graphics coding (RGC) framework, in MPEG, and we present the design of 3D mesh coding based on the RGC framework. In 3D graphics, there exist many overlapping object types (e.g., IndexedFaceSet in VRML, Mesh in Collada, etc.) in various formats. In order to design a standard that supports many different object types and their combinations, the MPEG RGC framework is proposed as a unified framework that covers everything, from object type definition to object compression, in a modularized approach. The RGC framework is largely based on the reconfigurable video coding (RVC) framework in MPEG. Currently, the RGC framework further extends the RVC to support a generic object type definition. In this paper, we provide a walkthrough on the use of the RGC framework with existing graphics coding standards such as MPEG 3D mesh coding.

Provides notice of upcoming special issue(s) of interest to practitioners and researchers.

3D polygonal mesh is the most commonly used representation for 3D graphic models. Compact and compressed representation of the 3D mesh is the major functionality of MPEG 3D mesh compression technologies. 3D mesh coding (3DMC) in MPEG was first standardized in 2000 with the achievement of compression ratio of more than 40 times with reasonable quality. In order to extend 3DMC with additional functionalities (e.g., efficient texture coordinate compression, support for animation/editing, etc.), 3DMC extension (3DMC-X) has been proposed and standardized. In this paper, we reviewed 3D model compression in MPEG in detail.

In this paper, we propose a novel method to describe the bit stream syntax and parsing of video coding. Multiple codecs are being increasingly used in many applications, so flexible and efficient design of multiple codecs in a chip is becoming a very important issue. In MPEG, a standardization activity called reconfigurable video coding (RVC) addresses the reconfigurable design of video codecs based on functional units drawn from the existing MPEG codecs. In the RVC framework, reconfigurable bitstream syntax and its parsing play an important role in allowing new requirements, such as reconfigurable syntax manipulation and bitstream level transcoding, to be posed in multi-codec environments. In this paper, we propose a compact decoder description language (CDDL) to efficiently represent the syntax parsing of bitstreams in a compact manner. The effectiveness of the proposed method is demonstrated through bitstream conformance testing, bitstream manipulation, and compactness evaluation of the parser description.

This paper presents the MPEG-4 Animation Framework eXtension (AFX) standard, ISO/IEC 14496-16. Initiated by the MPEG Synthetic/Natural Hybrid Coding group in 2000, MPEG-4 AFX proposes an advanced framework for interactive multimedia applications using both natural and synthetic objects. Following this model, new synthetic objects have been specified, increasing content realism over existing MPEG-4 synthetic objects. The general overview of MPEG-4 AFX is provided on top of the review of MPEG-4 standards to explain the relationship between MPEG-4 and MPEG-4 AFX. Then we give a bird's-eye view of new tools available in this standard.

Interpolator representation in key-frame animation is now the most popular method for computer animation. The interpolator data consist of key and key value pairs, where a key is a time stamp and a key value is the corresponding value to the key. In this paper, we propose a set of new technologies to compress the interpolator data. The performance of the proposed technique is compared with the existing MPEG-4 generic compression tool. Throughout the core experiments in MPEG-4, the proposed technique showed its superiority over the existing tool, becoming a part of MPEG-4 standard within the Animation Framework eXtension framework.

In this paper, we propose new technologies to compress the interpolator nodes in VRML/MPEG-4 BIFS (binary format for scene). Interpolators are used to animate the 3D objects in a VRML/MPEG-4 BIFS scene. For interactive applications with quite a few animated 3D synthetic objects, two components are dominant in the amount of data to represent the animation: 3D object and its animation. In the current MPEG-4, 3D model coding (3DMC) yields a high compression ratio with reasonable quality for the 3D object, while predictive MFField coding (PMFC) yields a moderate compression ratio with reasonable quality for the animation data. The proposed techniques are to provide a high compression on animation data and have been adopted to MPEG-4 system amendment 4 (AFX/MUW).

Here, we propose a new shape-coding algorithm called baseline-based binary shape coding (BBSC), where the outer or inner contours of an arbitrarily shaped object are represented by traced one-dimensional (l-D) data from the baseline with turning points (TP's). There are two coding modes, i.e., the intra and inter modes as in texture coding. In the intra mode, the differential values of the neighboring 1-D distance values and TP's corresponding to the given shape are encoded by the entropy coder. In the inter mode, object identification, global shape matching and local contour matching are employed for motion compensation/estimation. Lossy shape coding is enabled by variable sampling in each contour segment or by allowing some predefined error when performing motion compensation. We compare the proposed method with the bitmap-based method of context-based arithmetic encoding (CAE). Simulation results show that the proposed method is better than CAE in coding efficiency for intra mode and better in subjective quality for both intra and inter modes, although the CAE method has performed better than the proposed method in inter mode.

Here we describe a baseline-based binary shape coding method in which an arbitrarily shaped object is represented by the traced 1-D data from the baseline and turning point (TP). The shape coding is performed based on contour-based method in each separated shape. There are two coding modes in shape coding, i.e. the intra and inter mode as in texture coding. In inter coding mode, object identification, global shape matching, and local contour matching are used. In intra mode and residue coding, the DPCM values of TP and the 1-D distance values of the shape are encoded by a fixed arithmetic encoder. Simulation results show that the proposed method has a better coding efficiency and subjective quality compared with the block-based method, i.e. context arithmetic encoding (CAE).

MPEG-4 Visual, that part of the upcoming MPEG-4 standard describing the coding of natural and synthetic video signals, allows the encoding of video objects using motion, texture and shape information. In this paper, the shape coding algorithms and related texture coding algorithms that were thoroughly evaluated within MPEG-4 are reviewed. The evaluation leading to the selection of a block-based shape coder based on a context-based arithmetic encoder/decoder with motion compensation as well as padding and shape adaptive DCT for texture coding are presented.

In this paper, we present a segmentation based wavelet coding scheme, in which an image is segmented into two regions: stationary areas (background) and the areas containing edge information (foreground). These regions are then encoded independently using two dedicated encoders that are optimized for each region. A 2-D edge operator is used for segmenting the image. We use the embedded zerotree wavelet (EZW) algorithm for encoding the background due to its good performance on stationary areas. The foreground area is, however, encoded using a predictive residual vector quantizer (PRVQ). Experimental results show that the proposed technique improves the quality of the reconstructed images, both numerically (in terms of mean square error) and perceptually when compared to EZW at the same bit rate.

Discusses a method of compression of 3-D MRI images. A subband coding scheme with an octave splitting is proposed. The higher frequency subbands are encoded using an octtree structure. Octtrees provide a convenient data structure to store the sparse information present in the higher frequency subbands. Each unit block of the octtree is coded using a hybrid vector and scalar quantization scheme. The baseband is encoded using a DPCM based method using a nonlinear neural network predictor. This scheme provides an elegant way of compression of MRI images with minimum error.

A subband multistage vector quantization (SB-MSVQ) coding technique is proposed for wireless image communication. The Digital European Cordless Telecommunications (DECT) system has been used as a wireless communication environment. The impact of channel fading on the SB-MSVQ coding technique is investigated and its performance is compared with that of the baseline JPEG standard. Simulation results show that the proposed technique, SB-MSVQ, is very robust to channel fading errors even at a very low channel power, whereas the baseline JPEG suffers from channel fading errors which are visually very annoying. Due to the inherent structure of SB-MSVQ, the important low frequency information of an image is packed into a small portion of the encoded data. If this portion is received intact by the SB-MSVQ decoder, the overall quality degradation of the reconstructed image is marginal.>