Through mutual technology transfer between consumer and professional video recorders, the last 20 years has witnessed a rapid evolution from analog to digital recording. Each new digital videotape recorder (VTR) uses different channel coding. This implies that improving the recording density involves the development of new channel-coding schemes together with evolutionary magnetic tapes and heads. As a result, professional digital VTR's offer the best features for video recording. This paper reviews state-of-the-art magnetic recording devices, signal processing techniques for digital recording. It also describes the specifications for home-use digital recorders for current television systems, and discusses disk recording technology in the future.>

The author considers, mainly from the viewpoint of signal processing technologies, the current efforts for future home-use digital videotape recorders (VTRs). Recording technologies for future home-use digital VTRs are reviewed with respect to both current TV and HDTV systems. High-density recording and bit rate reduction are the major technologies needed for digital video recording with small cassettes. Recent experiments show that the technical problems, except those of equipment size and cost, have almost been solved.>

A new run-length decoding method for facsimile signal transmission is described. In this method, if an error code is detected in a received signal, the effect is localized in the runs corresponding to the error instead of the whole line to obtain better picture quality. The error immunity in this method can be used to shorten the transmission time.