ZDF has started transmitting a series of HD showcases in the last month as part of its migration to HD and has chosen 720p50, writes David Fox.
ZDF’s HD service will officially start with the Winter Olympics.
It chose 720p50, “mainly because it compresses better and gives higher picture quality at a given data rate,” (in this case 12Mbps – the constant bitrate ZDF has to use because it is sharing transponders with other broadcasters), Tobias Schwahn, TV systems engineer, Technical Innovation Office, ZDF, told the HD Masters conference. It is using 720p-native cameras (Ikegami in studio and Panasonic camcorders).
Germany is a problem market for rolling out HD. Cable is the main delivery method, but the availability of cables capable of delivering HD is patchy, with only about 25% of cable currently digital. As the analogue switch off for terrestrial has just finished, with SD now on DTT, it is too early to make another change to HD. Besides, DTT in Germany is designed for robustness, with about 13Mbps per multiplex, because it is primarily used for mobile and secondary services. Analogue switch off of satellite services is due in the next few years, with about 70% digital now.
ZDF is currently building two HD OB vans. The first, which should have been delivered by now, replaces a 17-year-old vehicle, while the second, due in 2010, replaces a 14-year-old OB. It also has a fly-away studio that it will use in Vancouver and South Africa next year. It has also recently built an HD news studio, although it has started operations in SD initially. “We have a lot of HD equipment already, but not fully put together,” said Schwahn.
It has installed a new, fully HD-capable playout infrastructure for five channels and one backup, which it is just starting the transition to, but it is using an interim solution for the showcases. Any new core infrastructure it is putting in (such as cables, switchers and routers) will probably be 3Gbps capable.
A remaining question is what it should to do with Teletext. This is very popular in Germany, so it needs to be able to transition to HD. “It’s not as easy as we thought. We cannot transport it in HD-SDI,” he explained. But as ZDF will simulcast in SDI, it could handle it in that. It had used MHP services for several years, but recently shut it down – with no complaints, as it wasn’t widely used. Instead, he believes hybrid broadband broadcasting services will be the eventual replacement for Teletext.