We propose a method to prevent the degradation of decoded MPEG pictures caused by video transmission over error-prone networks. In this paper, we focus on the error concealment that is processed at the decoder without using any backchannels. Though there have been various approaches to this problem, they generally focus on minimizing the degradation measured frame by frame. Although this frame-level approach is effective in evaluating individual frame quality, in the sense of human perception, the most noticeable feature is the spatio-temporal discontinuity of the image feature in the decoded video image. We propose a novel error concealment algorithm comprising the combination of i) A spatio-temporal error recovery function with low processing cost, ii) A MB-based image fidelity tracking scheme, and iii) An adaptive post-filter using the fidelity information. It is demonstrated by experimental results that the proposed algorithm can significantly reduce the subjective degradation of corrupted MPEG video quality with about 30 % of additional decoding processing power.

Hybrid image coding method is one of the most promising methods for efficient coding of moving images. The method makes use of jointly motion-compensated prediction and orthogonal transform like DCT. This type of coding scheme was adopted in several world standards such as H.261 and MPEG in ITU-T and ISO as a basic framework [1], [2]. Most of the work done in motion-compensated prediction has been based on a block matching method. However, when input moving images include complicated motion like rotation or enlargement, it often causes block distortion in decoded images, especially in the case of very low bit-rate image coding. Recently, as one way of solving this problem, some motion-compensated prediction methods based on an affine transform or bilinear transform were developed [3]-[8]. These methods, however, cannot always express the appearance of the motion in the image plane, which is projected plane form 3-D space to a 2-D plane, since the perspective transform is usually assumed. Also, a motion-compensation method using a perspective transform was discussed in Ref, [6]. Since the motion detection method is defined as an extension of the block matching method, it can not always detect motion parameters accurately when compared to gradient-based motion detection. In this paper, we propose a new motion-compensated prediction method for coding of moving images, especially for very low bit-rate image coding such as less than 64 kbit/s. The proposed method is based on a perspective transform and the constraint principle for the temporal and spatial gradients of pixel value, and complicated motion in the image plane including rotation and enlargement based on camera zooming can also be detected theoretically in addition to translational motion. A computer simulation was performed using moving test images, and the resulting predicted images were compared with conventional methods such as the block matching method using the criteria of SNR and entropy. The results showed that SNR and entropy of the proposed method are better than those of conventional methods. Also, the proposed method was applied to very low bit-rate image coding at 16 kbit/s, and was compared with a conventional method, H.261. The resulting SNR and decoded images in the proposed method were better than those of H.261. We conclude that the proposed method is effective as a motion-compensated prediction method.

In this paper, we propose a novel method of measuring the perceived picture quality of H.264 coded video based on parametric analysis of the coded bitstream. The parametric analysis means that the proposed method utilizes only bitstream parameters to evaluate video quality, while it does not have any access to the baseband signal (pixel level information) of the decoded video. The proposed method extracts quantiser-scale, macro block type and transform coefficients from each macroblock. These parameters are used to calculate spatiotemporal image features to reflect the perception of coding artifacts which have a strong relation to the subjective quality. A computer simulation shows that the proposed method can estimate the subjective quality at a correlation coefficient of 0.923 whereas the PSNR metric, which is referred to as a benchmark, correlates the subjective quality at a correlation coefficient of 0.793.

This paper presents the basic design and principles of an FQDN-based Internet Architecture, where a host is identified in the Internet only by its FQDN (Fully Qualified Domain Name). The address shortage problem for the IPv4 paradigm has been marginally solved by introducing private addresses within the intranet and also by DHCP for public Internet access services. These two approaches have been independently developed. Considering more elaborate peer-to-peer communications such as voice over IP (VoIP) in the future Internet, the shortage of address space will become a serious problem for a call or session to be established. To alleviate this, this paper proposes an FQDN-based Internet architecture, assuming that a global endpoint identifier (EID) in the network is FQDN instead of an IP address. Since a countably infinite number of addresses can be logically produced by FQDN, this system resolves the address shortage problem assuming a caller uses the FQDN of the called terminal or host. This requires a dynamic address loading system from the FQDN of the called terminal into one of the available public IP addresses. After proposing a possible address loading system, some mathematical results on the required number of public addresses for VoIP traffic, the address space size of the derived Internet, etc. are also presented.

This paper proposes a new approach to the problem of efficient digital coding of the NTSC composite color TV signal. First, a new method, named Comb-Filter Integration method", of deriving a prediction function effective for the NTSC composite signal is introduced. This method is based on the technique of integrating a simple comb-filtering operation into an arbitrary linear prediction function tailored for monochrome TV signals, and thus coverting it to a prediction function effective for the NTSC signal. Practical examples of such composite prediction functions are shown. Then, 32 Mb/s and 44 Mb/s DPCM systems, using one of these prediction functions, are described along with their simulated performances. The results show that these systems are promising for the high-quality transmission of the NTSC signal.