New Zealand broadcaster TVNZ used 16 of Crystal Vision’s TANDEM HD-21 High Definition audio embedders/de-embedders to add commentary to more than 800 hours of coverage from the Beijing Olympics and Paralympics, with the broadcasts distributed to 104 countries around the world and watched by more New Zealanders than any other television event.

The Olympics host broadcaster supplied all 40 incoming feeds to TVNZ with eight embedded audio channels. TVNZ needed to replace the Low-Frequency Effects channel with mono commentary on all of its coverage, and selected the TANDEM HD-21 for this purpose because it could overwrite a single audio channel and also had the benefit of being a space-saving single module. Adding commentary at the start of the production chain ensured the pictures and international sound always had the right commentary, whether it was being taken live to air in the production suite or recorded on a server for later replay. All the events requiring commentary were routed through the TANDEM HD-21s, with TVNZ using 16 boards because they needed to handle a maximum of 16 events a day.

The TANDEM HD-21s were located in the equipment room of TVNZ’s space in the International Broadcast Centre in Beijing, which included two HD production facilities: one for TVNZ and the other for SSI (Super Sport International) – the sports division of South Africa’s MNET. The overall TVNZ production facility consisted of a production suite to put events live to air, and an extensive EVS server system for recording and editing events for delayed replay to fit in with the production schedule. HD signals from the host feeds were switched from a central router into the TANDEM HD-21s, and then the output of the TANDEM HD-21s with embedded commentary re-entered the router for use within the TVNZ production facility.

The TVNZ HD signal was conveyed to New Zealand by fibre and transmitted on the TVNZ DTT digital terrestrial multiplex, while the SSI HD signal was distributed throughout South Africa, Asia and the Arab States via satellite. The TVNZ HD signal was also down converted to SD for transmission on the TVNZ DTH satellite platform, for the legacy analogue transmission system and as a streaming source for the website. A multi-channel control room in the TVNZ space produced eight SD services which were distributed to 104 countries, including New Zealand, South Africa, Asia and the Arab States.

TANDEM HD-21 wasn’t the only Crystal Vision product that TVNZ used for its Olympics coverage. A large number of Demon de-embedding monitors were also used to de-embed the down converted output from the TANDEMs to allow the effects and commentary to be mixed before transmission.

TVNZ housed the TANDEM HD-21s together in one 4U frame (which holds up to 24 boards) as it was the most economical way to package the number of boards they required. The Statesman PC software was selected for control as it would make it easy to configure and control the TANDEMs’ advanced features on the next event.

The TANDEM HD-21s, which were supplied via Crystal Vision’s distributor Mastatek, will be used for events work in the future and planning is already underway for four events in 2010. TVNZ will be taking advantage of the configurability of the TANDEMs and will be fitting analogue output piggybacks this time to allow simultaneous de-embedding of the incoming signal. TVNZ will be using TANDEM HD-21’s advanced features – including two group handling, gain adjustment, stereo to mono conversion, channel shuffling, audio replace and 64ms audio delay – at the forthcoming events.

TVNZ is New Zealand's biggest free-to-air broadcaster and the nation's television public broadcaster. The channels operated include TVONE, TV2, TVNZ 6, TVNZ 7 and TVNZ Sport Extra as well as New Zealand's online television viewing and downloading website, TVNZ ondemand.

Based at Whittlesford near Cambridge in the UK, Crystal Vision provides digital keyers, picture storage modules and a full range of interface equipment including converters, decoders, encoders, distribution amplifiers and audio embedders to the professional broadcasting industry worldwide.