Posted by Thomas Heritage on , last updated

It's now more than 18 months since File Delivery Day (1st October 2014) which signalled the start of all UK broadcasters receiving television programmes as computer files rather than as videotapes. In that time the BBC alone has successfully transmitted more than 10,000 programmes from files.

Since then we've been working on modernising how the Specifications for these computer files are written so we could more easily expand to meet the needs of broadcasters from around the world. Just last month at the NAB broadcast technology show in Las Vegas the North American Broadcasters Association (NABA) announced the 8th and 9th Specifications in the family: delivery of HD television programmes to broadcasters in Canada and the United States.

Expanding the AS-11 family

The success of file delivery in the UK is a result of collaboration between UK broadcasters, manufacturers and suppliers through the Digital Production Partnership (DPP) and a partnership with the Advanced Media Workflow Association (AMWA). We have made a large contribution to the technical work of this collaboration with a focus on the AMWA AS-11 Specifications and their implementation.

The AMWA AS-11 family of Specifications define file formats for the delivery of finished media to broadcasters or publishers. Each Specification is developed for a particular business purpose. Currently the members of the family cover:

  • DPP SD & HD – these are very well established as the file formats for delivery of SD & HD television programmes in the UK. We have worked with the DPP Compliance Programme to ensure products from numerous manufacturers can correctly create, play or analyse files that comply with the AS-11 DPP HD Specification ahead of AMWA certification. To date fifteen products have gone through the process and been certified by the AMWA.
  • DPP UHD – introduced at the beginning of this year this meets the requirements of the UK broadcasters for the next generation of television programmes: Ultra High Definition (UHD). This allows higher resolution pictures with more colours and high dynamic range as well as more flexible audio.
  • International SD & HD – the benefits of the UK's approach to file delivery have been recognised around the world. These new Specifications were introduced at the beginning of this year and have been created for use initially in the Nordic countries, Australia and New Zealand for SD & HD television programmes
  • NABA DPP HD – announced just last month, these two HD programme Specifications are for use when delivering to certain broadcasters in Canada and the United States.

The DPP also announced Specifications for commercials (adverts) and promotions in January – these are based on the existing AS-11 DPP HD Specification and will join the AS-11 family later in the year. As a result, ITV (one of the other DPP broadcasters) has now started transmitting HD commercials – they were limited to just SD before.

Making Specifications from building blocks

AS-11 is now a large family of Specifications. All the family members have a lot in common but they also have their own particular characteristics.

If we had written each Specification as a simple Word document then a lot of copy-and-paste would have been involved. It would have been impossible to keep track of all the Specifications let alone produce something suitable for developers to implement easily in their products. So instead we developed our ideas for "rules based" Specifications: these are Specifications that are made out of building blocks. A whole catalogue of building blocks has been created and can be assembled in different ways to produce the AS-11 Specifications. Some of the building blocks are used in all of the Specifications and some are custom-made for a particular Specification.

A small piece of a rules based Specification (showing some of the building blocks) presented as an interactive webpage – view the full Specification

 We have also made use of developments in the AMWA which are inspired by the way modern Internet tools and Standards are written. The result is that we treat Specifications much more like software and publish them on the popular software hosting service GitHub. We also make sure they are available while still a "work in progress" so we can get others to review our designs as soon as possible.

We will explain more about this approach in a future blog post. In the meantime, links to all the new Specifications can be found on the AMWA website.

Bringing it all to life

We've already updated our open source reference toolset "bmx" to work with many of these new Specifications and have created a selection of sample files that can be downloaded by anyone.

Next we will be working with the AMWA to explain the new Specifications at a Webinar on 13 May 2016 and with the DPP to run a PlugFest on 12 July 2016. Both events are open to all those interested in implementing the new Specifications.

The DPP and the AMWA announced recently that they will provide testing and certification of products that implement any of the HD & UHD Specifications in the AS-11 family. This will help give people confidence in the ability of these products to work together correctly. This will be another important focus for our work during the next part of this year.

How to find out more