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Blog: Driving Interoperability in new AS-11 Specs

On the 12th of July, the DPP held its first PlugFest looking at the new rules based AS-11 specifications. Primarily focused on the UK UHD and NABA HD AS-11 file formats, the event brought together developers and product managers from a range of broadcast equipment manufacturers and software providers to enable the exchange of content, information and sample files.

The goals of the day were to:

  • Drive adoption of DPP UHD and NABA | DPP HD delivery specifications;
  • Help move forward relevant AS-11 specs from “Work in Progress” to “Proposed Specification”;
  • Provide a temperature check on the maturity of interoperable systems and equipment development;

The day started with an information update from Tom Heritage of BBC R&D, presenting the details of the AS-11 X series of specifications. Tom outlined the new rules-based structure of the specifications, the Request For Comment (RFC) process, publication through GitHub, and the international variants of the X series of AS-11 file specifications. Paul Drewett, the DPP Test Lab manager, then laid out the process we would be using for the day.There were 11 companies testing their equipment at the event, from across the entire broadcast production and distribution chain. The companies attending brought products that specialised in file-based QC; transcode; edit; video servers; MAM; workflow; and audio processing. All participants signed a confidentiality agreement, so we can’t provide details about the results, but below you will find some of the high-level themes from the day.

To sum up the output in a few words, it can be simply put as “better than expected!”. Everyone present could demonstrate some level of functionality for file playback. Many of those attending were also able to process metadata and/or (un)wrapping, and a number of the tools could create files too.

In terms of XDCAM essence for the NABA DPP X8 Specification, compatibility was very good, although pre-charge and rollout support was not always present. Long GOP AVC for UHD is also not always well implemented for MXF files, but it doesn’t seem like a big stretch for most. Encoding of UHD isn’t in a lot of products yet, but definitely on the roadmap of those we spoke to. Hardware requirements were something that will need to be looked at as processing or playback of UHD AS-11 X1 files required powerful equipment.

Metadata wrapping and unwrapping was moderately well supported. For those used to wrapping XML blobs in an MXF file it was just a matter of creating the right structure, so although it was handcrafted, the support was definitely there. There were even a couple of pretty complete files, which need a deeper level of analysis to confirm that they conform to the spec, but certainly appear to be pretty close.

The AS-11 implementation of multichannel audio labelling borrows much from IMF, so the level of product maturity in this space depended very much on whether their products support IMF in any way. Even for those who hadn’t come across it before, there appeared to be a clear understanding and a path towards eventual support.

Putting it all together, the impression of those present seemed to be that most of the building blocks for support of AS-11 X1 – DPP UHD and AS-11 X8 – NABA | DPP HD MPEG-2 are already in place. Stitching those building blocks together into a product ready for release will obviously take time, but all in all it was a very successful day that gave everyone present a lot to think about.

This blog post was written by Tim Davis, Senior Enterprise Architect, ITV and DPP UHD Lead.

To find out what some of those taking part thought, see our short summary video: