HD-MAC

HD - MAC is a further development of the MAC process to an analog HDTV system with 1250 lines, of which 1152 visible. It was the early 90s in Europe for test transmissions in use, including during the live broadcast of the Olympic Games in 1992 in Barcelona.

The bandwidth and therefore the horizontal resolution is doubled compared to D2-MAC. The line frequency is, however, for reasons of compatibility 15625 Hertz, so that four sub- images are needed for a complete picture. This results in the recording of the vertical resolution of three ways:

• 50 frames per second with 288 lines for rapid image areas,
• 25 frames per second with 576 lines for normal - moving areas of the image or
• 12.5 frames per second with 1152 rows for particularly quiet areas of the image.

The image is further divided into blocks of 8 × 8 pixels, to each of which the appropriate deinterlacing method is specified.

During playback, the decoder must digitally cache the image and transform it back by repeatedly reading out the memory back in 50 or 100 images. The image format HDTV cameras and CRT TV receivers was the first time in Europe 16:9. HD-MAC signals were backwards compatible with D2-MAC receivers.

The system never came into devices for consumers on the market. Although the actual transfer was analog, HD-MAC needed much - at that time expensive - digital technology. In addition, except for expensive and bulky tube sets and a few also expensive projectors no screens were available that could have represented the HD signal. In parallel, it became clear that all-digital broadcasting technologies such as DVB or ATSC would be available. In addition, the industry had a smooth transition planned by D2 - MAC SDTV transferred to compatible HDTV via HD - MAC. This would have provided a larger installed base of D2-MAC receivers that never materialized.