Yoshinori Hatori

Comparison Between DPCM and Hadamard Transform Coding in the Composite Coding of the NTSC Color TV Signal

Since differential-pulse-code modulation (DPCM) and orthogonal transform coding (OTC) are the most fundamental methods of high-efficiency coding (bit-reduction method), it is important to clarify the basic coding characteristics of these methods and the difference between them in order to utilize the bit-reduction method effectively. This paper theoretically as well as experimentally compares the coding efficiency of a DPCM having a two-dimensional predictor with that of a two-dimensional Hadamard transform coding method (HTC) in the intrafield coding of the NTSC composite signal. The comparison evidenced that the distinctive difference in coding characteristics between DPCM and HTC depends greatly on the power level of carrier chrominance signals. That is, it is confirmed theoretically and experimentally that the coding efficiency of the HTC is far lower than that of the DPCM in the case of a signal having a high power level carrier chrominance signal such as a color-bar signal.

15/30 Mbit/s Universal Digital TV Codec Using a Median Adaptive Predictive Coding Method

This paper describes a 15/30 Mbit/s TV codec with a new approach to high-efficiency coding for TV signals, i.e., median adaptive prediction. The 15/30 Mbit/s codec, commonly applicable to NTSC, PAL, and SECAM (525/60 and 625/50) systems, uses adaptive prediction incorporating a motion-compensated interframe, an interfield, and an intrafield predictor. Its performance for digital transmission is presented. This universal codec is designed, based on CCIR recommendations concerning digital TV coding parameters for studios (Rec. 601) and general principles on long-distance digital TV transmission (Rec. 604). A field trial of 15 Mbit/s digital TV transmission using this codec between earth stations with a 30 m diameter antenna and a 5 m diameter antenna is reported.

30 Mbit/s Codec for the NTSC Color TV Signal Using an Interfield-Intrafield Adaptive Prediction

This paper proposes a new approach to the composite coding of the NTSC color TV signal, i.e., an interfield-intrafield adaptive prediction. First, concerning prediction efficiency for various moving pictures, an advantage of this coding scheme over interframe coding is clarified theoretically and experimentally. This adaptive prediction gives very good and stable performance for still to violently moving pictures. A 30 Mbit/s. codec, based on this idea, and its performance are presented. Field transmission testing through an INTELSAT satellite using this codec is also described. The picture quality is satisfactory for practically all the pictures expected in broadcast TV programs, and it is subjectively estimated to be a little better than that of the half-transponder FM transmission now employed in the INTELSAT system.

Inter-videotex conversion from Prestel to Captain

The authors describe a data syntax conversion method from CEPT (European standard) to Captain PLPS (Japanese standard) to permit interconnections between videotex services. They discuss the conversion results when an overseas videotex center, in particular, the Prestel (alpha-mosaic version in CEPT standard) center in the United Kingdom, is accessed from a Captain terminal using the described method. By the conversion method presented, the Captain terminal can access CEPT videotex centers as a CEPT terminal. There are two essential features. The first is that text and graphics data are converted into photographic information on Captain terminals to absorb differences of character size and graphic display. The second is that a color replacement method based on the major colors in a coloring unit is used to solve the problem of differences of coloring units between the two videotex services. >

Characteristics of Interfield and Intrafield Adaptive Prediction Coding for NTSC Composite Color TV Signals

NTSCカラーテレビ信号の新しい高能率符号化技術として, フィールド間・フィールド内適応型直接予測符号化方式を提案し, その基本特性を明らかにする.次に, この検討に基づき製作した30Mbit/sec符号化装置と同装置を用いて行った符号化実験結果, インテルサット衛星によるカラーテレビディジタル伝送実験結果を述べる.