Full digital delivery on the horizon

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Digital file-based production is here and it is predicted that by 2014 most international broadcasters will prefer digital format delivery.

While TV production has been digital for some time, it is digital tape that has been used as the means of exchange between different parts of the production workflow. The emergence of file-based cameras, however, removes tape from the acquisition stage of the produc­tion process, and this in turn prompts the production community to look at entirely end-to-end file-based work­flows.

While most international broadcasters prefer digital format delivery – particularly in the UK – the Digital Production Partnership (DPP) recently released details of its agreed standards for the metadata, format and codec quality for delivering content in digital formats.

The DPP was formed in March 2010 by the UK’s public service broadcasters to help producers and broadcasters maximise the potential benefits of end-to-end digital production in television. It is funded by ITV, BBC and Channel Four, with representation on its various work streams from Five, Sky, S4C, UKTV, independent production companies and other key stakeholder bodies.

The partnership has two primary areas of activity. The first is a commitment to establish common technical standards between UK broadcasters (the partnership has already achieved this aim for file-based programme delivery). The second area relates to establishing best practice digital production processes and workflows.

Working closely with the Advanced Media Workflow Association (AWMA) in the United States, the DPP was the driving force behind the creation of the organisation’s “AS-11,’ a new international file format for HD Files. The new DPP guidelines will require files delivered to broadcasters to be compliant with a specified subset of this new, internationally recognised standard. Alongside these new standards, the DPP has released a free-to-use, downloadable, metadata application to enable production companies to enter the required editorial and technical metadata easily.

Several of AMWA’s specifications target the simplified use of MXF, a file wrapper standard from SMPTE. There are three related Applications Specifications (AS) designed to button-down the usage profiles and thereby improve interoperability.

They are:
• AS-10: MXF for production
• AS-11: MXF for contribution
• AS-12: MXF for commercial delivery

The new standards aim to remove any ambiguity during the production and delivery process. A key aspect is the inclusion of editorial and technical metadata, which ensures a consistent set of information for the processing, review and scheduling of programmes, as well as onward archiving, sale and distribution.

Noreen Adams, BBC head of Metadata and chair of the DPP Metadata Standards Working Group, comments: “Accurate metadata is now fundamental in identifying programmes and the agreed metadata standards contained within the DPP application helps to simplify file delivery for producers and broadcasters.’

A brief rundown of the AMWA specification, known as AS-11, reads as follows:
• Each programme should be delivered as a single principal MXF file containing the audio and video, plus a single XML file. There must be only one programme in each file, although a programme may be either soft or hard-parted within that file, as specified by the broadcaster.
• Each high definition programme must be delivered as a single MXF OP1a file. The video essence in the file must be encoded at a nominal bitrate of 100Mbit/s using the “AVC Intra’ codec. It must use the High 4:2:2 Intra profile@level 4.1.
• HD video must be recorded with an active picture area of 1920 x 1080 pixels. This must normally be structured as interlaced at 50 fields per second, described as System 2 in EBU-TECH 3299. Material may be originated as progressive scan, but should be delivered as interlaced. Also note the requirement; that moving graphics and effects, such as credit rollers and DVE moves are always interlaced.
• The audio must be frame interleaved with the video. All audio tracks must be encoded as PCM with a sample rate of 48kHz at a depth of 24bits/sample.

First in DPP

Sunset+Vine, producers of the America’s Cup, became the first to deliver to a UK broadcaster in the DPP file-based specification using the metadata application in November 2012. They used the application to add in editorial and technical metadata and re-wrap the file to the DPP standard.

Channel 4 then downloaded the 30-minute programmes and associated xml files from its delivery site. Elsewhere in the production process, Sunset+Vine provided archiving and global distribution for America’s Cup Uncovered, a 30-minute weekly HD magazine programme delivered to more than 400 international broadcasters.

I guess it’s a good time to start looking at transcoding servers to replace HDCAM and SR decks so you can output the required files quickly and efficiently.

As Kevin Burrows chief technology officer of Broadcast and Distribution, C4 and DPP Technical Standards chair, says: “Having one set of standards for file-based delivery across the industry is of huge benefit to ensure ease of exchange and compatibility. It will also reduce costs for independent producers as well as minimise confusion among programme makers.’

By Ian Dormer

screen africa magazine – january 2013

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