The 4 : 2 : 2 Profile, which is a new profile for the MPEG-2 video standard, is intended for applications that use high quality video applications. The 4 : 2 : 2 Profile at Main Level permits better color resolution, allows coding of all active video lines and can operate at a bit-rate up to 50 Mbps. This allows flexibility in choosing video quality and latency that are stecific to the needs of studio applications, such as multiple generation coding (repeated encoding and decoding), digital effects and digital distribution. This paper describes the outline of the 4 : 2 : 2 Profile and shows its performances through quality vernfication tests.
MPEG-2 Verification Tests were carried out for 5 different combinations of Profiles and Levels by several organizations in the world from January 1994 to December 1995. These verification tests were organized according to ITU-R Rec. BT.500 and BT.710 and DSCQS method was used. The assessment tests were carried out by each organization and the data were submitted to the MPEG Test Chairman. The outline of the results were reported at MPEG meetings. This paper describes the test procedure, test materials and the details of the tests results of MPEG-2 Verification Tests for SNRP@ML, SSP@H-14 and MP@HL(H-14).
We developed a digital compressed picture quality assessment system, in which a real time calculation of a picture quality degradation can be conducted. In this system, human visual perceptions : noise sensitivity in spatial frequency, noise masking effect by a local video activity and gazing point disturbance by a global video activity are considered. An accuracy of picture quality assessment is, therefore, greatly improved compared with a conventional SNR method.
OFDM (Orthogonal Frequency Division Multiplexing) is a modulation scheme that uses many carriers and has superior characteristics under multi path environments compared with single carrier schemes. Therefore, it is expected that mobile reception and SFN (Single Frequency Network) can be realized using OFDM. However, there is a problem that it is difficult to choose suitable transmission parameters for both mobile and fixed reception. This paper proposes a system which uses a TDM (Time Division Multiplexing) scheme and multiplexes symbols with different lengths for mobile and fixed reception. This paper also shows the results of a computer simulation.
Experiment of 64QAM signal transmission by tentative specifications of Ministry of Posts and Telecommunications at Advanced Cable Technology Center, Nihon Network Service Co., Ltd. and LCV Co. were described. C/N of more than 26dB, Composite Triple Beat (CTB) of less than -43dB and a CW carrier interference of less than -30dB were required to keep BER of less than 1×10^<-4> without a forward error correction. Flawless decoded MPEG2 pictures were obtained in these experiments.
Through utilization tests or the 64QAM signal under tentative specifications, intensive works have been made to standardize digital broadcasting signal format over cable television systems. At first, we describe an indoor experiment on the adjacent interference between the 64QAM signal and 3 types of analog modulation signals so far being supposed to transmit through cable television facilities. Next, we describe field tests conducted at 2 operative facilities under allowable ranges of DU ratio.
Standardization of digital broadcasting system and prior to the tentative speculation, we conducted measurement of various characteristics, including Carrier to Noise Ratio, Composit Triple Beat, Group Delay and Input Level at Outlet of 5 operative facilities of urban type cable television for the purpose of determining the level of operative facilities and correlation thereto of the capacity of the field testing facilities.
In multi-channel optical cable TV systems, non-linearity of a laser diode causes a number of distortions (CSO, CTB, etc). These distortions and thermal noise are main causes of the degradation for the BER performance of the digital-modulated signal. We measured characteristics of CSO and CTB in a digital modulation channel. Experimental results show that CTB's contribution to BER degradation is larger than that of thermal noise and the amplitude distribution of CTB differs from the Gaussian distribution.