Necessity and Possibility of Separate-Components Digital Video Recording

A score of countries in the world, most notably France and the USSR, are now committed to the SECAM standard of color television. Research efforts, however, regarding the possible digitization of SECAM signals have lagged relative to PAL and NTSC research because only one of the 20 countries is a Western European country with advanced technical facilities. SECAM signals, having definite advantages for on-air transmission, require demodulation and remodulation if they are to be mixed in composite form. This unfortunately would cancel out the sought-after advantages of digital recording — ease of signal processing and transparency through multiple generations of recording. A feasible components-encoding system, developed by EBU Working Party C, is described as a satisfactory alternative. For various reasons, mainly improved compatibility with composite PAL, luminance is sampled at about twice the PAL subcarrier frequency (at 8.87 MHz.); two simultaneous color difference signals are used, both at 4.43 MHz. Error correction and concealment, bit rate reduction (to about 100 Mbit/s by elimination of H blanking and use of other techniques), and DPCM coding are among the subjects covered. The components technique is seen as a proper subject of study not only for present or potential SECAM customers but also for those seeking a unified or at least a compatible digital video recording standard.

Print ISSN

0036-1682

Published

1980-03

Content type

Original Research

DOI

10.5594/J01632