While delivered over BT broadband to the home, the production from the venue is in quad-HD SDI.

“The increased bandwidth requirements of 4K production means choosing between the relatively clunky use of 3G-SDI bundles, looking towards higher bandwidth SDI (12G-SDI or above) implementations or moving to high bandwidth Ethernet technologies,” explains Steve Plunkett, CTO at Ericsson Broadcast & Media Services, which is responsible for managing BT Sport's channels including BT Sport UHD, BT Sport Europe, free-to-air service BT Sport and a red button service.

“Most organisations seem to be using 3G-SDI bundling as a stop gap approach while planning and evaluating the Ethernet options for the future. That seems a sensible approach.”

Ideally, BT Sport and Timeline want to get to a position where they are sending one truck to perform one workflow – a 4K down-rezzed to HD – for both 4K and HD live outputs. Getting there will be an evolution. While Timeline's truck can accommodate up to 16 camera positions, it is likely that regular match coverage in 4K will require fewer, maybe eight positions.

“Because of the extra detail in 4K you can use wider shots than you would in HD,” says Daniel Mcdonnell, owner and director at Timeline Television. “Shots from the corners work well as wide. These 4K production methods will start to emerge as we produce week in week out.”

Specialist remote and radio links like ref cams, tunnel cams and pitch side handhelds will be upscaled from HD until latency in encoding can be matched with audio for live work.

Other elements of the chain not yet catered for in 4K include live super slo-mos for which Timeline is using the iMovix camera. “It delivers great pictures but can't be used as a main replay angle as easily because you can only record for a short time,” explains McDonnell.

BT circuits from all 20 Premiership grounds bring the live 4K signals into BT's Stratford headquarters. Signal test is made on Tektronix waveform units with footage viewable on Sony PVM-X300 4K monitors and passed to Red Bee for transmission over BT fibre.

Back in the OB the ISO angles are recorded to EVS XT3 4K servers with the director's cut recorded on a Sony 4400 server. All of that media is transported to BT Sport's studio in Stratford on 10Gb removable hard disks and ingested into a 2 Petabyte Harmonic Media Grid. This media is used to cut promos, features and analysis for sundry programme packages. Items such as video to music clips can also be cut in the OB truck on Adobe Premier and streamed back in 4K over fibre to Stratford.

“The amount of media is huge, there's so much more data to track and we need to track and view it in 4K,” explains McDonnell. “That's complicated because there isn't a 4K viewer available for edit suites at the moment.”

Consequently, Timeline and BT are developing a bespoke asset management system to work in 4K. “EVS IP Director will be able to handle 4K but we're not there yet and we need a solution quickly to allow us to manage the assets,” he says.

A robotic tape library links into MediaGrid as deep archive and the UHD workflow will likely be similar to the HD one currently in practice.

“Media comes back on drives and is plugged into the Mediagrid. The content is logged and archived to LTO tape and a low res copy is made available for anybody to view on their desktop using EVS IP Browser,” says McDonnell. “Producers can select the clips they need and send them to Avid for craft editing. If the media resides on Harmonic the media is sent straight away. If it is on LTO then there's a partial restore of the file to Avid.”

With a number of 4K cameras in the market from For-A and Grass Valley, Timeline's choice was dictated by being able to mix and match accessories and operator skills from its existing Sony HD fleet of imagers.