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Chelsea Flower Show blossoms in HD

The RHS Chelsea Flower Show, which took place last week, is one of the BBC's most complex outside broadcasts of the year, with two or three magazine-style programmes each day, some of which are completely wireless.

The RHS Chelsea Flower Show is the world’s most important annual horticultural event, a dazzling display of colour, royalty and celebrity that attracts exhibitors and viewers from around the world. It is one of the BBC’s most complex outside broadcasts of the year, with two or three programmes each day, some of which are completely wireless, writes David Fox.

There is more than 11 hours of programming during the week. This includes a daily, 30-minute lunchtime show, which is live with recorded-as-live reports (all done wirelessly), and 60 or 90-minute evening shows (with two 60-minute programmes on separate channels on the opening night).

To produce all of this content, the majority of which is shot at the show, there are essentially two operations. There is a live outside broadcast unit, with six wireless cameras (one on a jib – with a seventh camera on another jib on the first day, to cover the royal visit and attendant celebrities).

There are also five portable single camera units (PSC crews), plus five Avid edit systems connected to an Avid server. There are two further Avid systems in the production area, for logging tapes from the PSC units, although only minimal metadata is produced. “It’s mainly just a mad scramble to get in on air. There isn’t enough time to log it comprehensively,” said Ian Haynes, engineering manager, SIS Live, which provided the facilities for the event.

“We also have three cable cameras that go to the studio position [overlooking the main walkway through the site] where we do links and present the evening programme from.”

To produce all the items needed to fill multiple magazine programmes during the week, the BBC Birmingham production team has developed an efficient workflow. “It’s challenging for the production team as it’s the only live OB they do,” he added.

The OB unit operates as two teams of three cameras, allowing one to set up, while the other is recording a piece in one of the show gardens or the huge flower pavilion. Generally, these will be shot once with a presenter and interviewee, and recorded through the vision mixer to an EVS system. Then that piece will be played back through the vision mixer while the three cameras are used to shoot the cutaway shots of plants, etc., in the garden, and published to the Avid server. After that, the second team records its piece while the first team moves on to another location – thanks to the heavy crowds “you can’t move quickly between each garden,” explained Haynes.

Those items are shot as live and mixed live, but there are also items that have been shot by the PSC crews (mainly for the evening shows), and all of these end up on the Avid server.

The evening programmes are effectively shot and edited on the day of broadcast. “Because of the time constraints, we don’t have time to produce one edited programme complete,” instead segments of the show are put together as they are ready, then played out during transmission from the EVS system. “We are usually still editing some of the programme when we are starting playout. It’s quite a tight deadline,” he said.

Wireless Links

“We used to cable the whole site, but because of health and safety they couldn’t be put on the ground, so we used to have a whole week of putting in triax and fibre for the audio, and having to string them through trees,” said Haynes.

Chelsea had been one of the BBC’s first big events to move to HD, but then fell victim of financial tightening so that after two years of HD it reverted to two years of SD, for which it went wireless. This year it has come back to HD (as BBC One has moved fully HD, alongside the existing BBC HD channel), but remains wireless. “It’s rare that a whole show is completely done on radio cameras,” which made it particularly important to retain the full quality and all the facilities they would have had with cables.

To ensure this, SIS did tests with BBC R&D, to ensure that any system could handle all the rich colours, especially the reds, and the fine details, such as all those green leaves constantly swaying in the wind.

It chose a Link HD wireless system, which enables it to deliver the mixer output and autocue to the cameras, along with data control for colour balance, cue light, etc. There are two diversity receive points in the pavilion and two in the production area.

The wireless links are effectively used as a dual-channel system, to give them the widest possible bandwidth (18MHz using two 9MHz channels). To ensure the quality remains high during its satellite contribution feeds, it did further tests to maximise its bandwidth there too, with a 48MHz feed.

“The aim is to give the best quality we can for the viewer at the end,” he said.

Portable single camera

The PSC units were originally going to use HDCAM cameras, but they couldn’t get enough tape stock, because of the Japanese earthquake and tsunami, so they decided to move to Panasonic DVCPRO HD because the tapes were available.

They opted to stay with tape for the production rather than moving to a file-based format because the production team were familiar with the workflow and the format was fully compatible with all the post-production equipment, so that there would be no need to transcode anything between the Avid and EVS systems.

For audio, each crew has an equipment trolley, with the wireless audio receivers and audio mixer, and each presenter (Rachel de Thame is pictured left) has their own radio microphone and their own frequency, so that when a presenter moves between crews they adjust the receiver rather than the presenter’s system. For non-PSC units, the output of the mixer is then sent via the camera’s wireless link. It can then be mixed with atmos tracks from extra microphones positioned around the grounds.

Due to the delay on the wireless links, the presenters work with switched talkback, because they would hear themselves out of sync if they used open talkback.

There is also a lot of further material shot for the BBC’s Red Button service, providing further, comprehensive, coverage of individual gardens or other topics. As this goes out on a highly compressed, standard definition digital channel, it is shot in SD on Digital Betacam, to save money. It has its own area on the server and any HD material it uses is downconverted. It is run as a separate operation, with three cameras and a Polecam jib. There is also material being produced every day for the BBC’s online coverage.

The OB teams arrived on the Thursday before the show to set up, although an advance crew came in a week before that to put in triax cable to the two wireless receive points inside the pavilion (which had to be done before exhibitors moved in).

Rigging of the portacabins and studio took two days, and crews started shooting on the Saturday afternoon for the first transmission on the Sunday. The last original programme went out the following Saturday, when a highlights show for the next day was also edited.