All-IP broadcast: It's when and how, not if

Andy Warman, Harmonic
September 15th 2016 at 4:09PM : By

For Andy Warman, Harmonic’s director of production and playout strategy and market development, the transition to an all-IP broadcast infrastructure is a matter of when and how, not if

We often note how quickly technological changes take place and reshape our world. And the landscape surrounding the transition from SDI to IP is no different. It has changed dramatically in just the past six months.

Where once there was uncertainty about what underlying technology the industry as a whole could embrace to move to all IP, now broadcasters appear to have settled on the AIMS approach as the right way to move forward. At the same time, vendors have embraced this direction and have been able to show interoperability with everything from cameras to encoders, and practically everything in between. This is good news for everyone as there is now a clear path guiding the transition and ensuring that broadcasters have compatibility between devices and vendors.

How broadcasters will make the move to IP will vary. Generally, they will fit within one of three different groups: ready to make the move to IP now, able to make the move to IP in stages, or still need to wait and see. All three face similar requirements.

Move to IP now

  • Both budget and location allow for an all-IP system to be built
  • Currently available technologies are suitable for required workflows
  • Existing standards and specifications are acceptable
  • Upgrading systems as standards evolve is acceptable

Move to IP in stages

  • Budget and location are flexible enough to allow implementation of IP in the workflow
  • IP can solve some but not all workflow needs
  • Standardisation has not yet solved all IP requirements

Wait and see

  • Budget and/or location restrictions mean SDI remains for the time being
  • Workflow needs cannot be solved by IP
  • Standardisation work must be completed prior to IP investment

Regardless of where a broadcaster is in the process of moving to IP, it has become a foregone conclusion that at some point the industry as a whole will move to all-IP protocols. This shift offers a number of clear advantages.

For one, having a single medium for the transport of all media simplifies infrastructure requirements. As a result, there is no longer a separate island for production, news or playout.

IP can scale and adapt in a rapidly changing environment. Broadcasters working in the IP realm thus can provision network resources and related compute and storage whenever they need to change a process or workflow, add a new channel, or bulk up to support higher resolutions or higher data rate codecs. Because IP-based systems are aligned both with the move away from reliance on proprietary devices in production systems and air chains and with the move toward COTS computing, cloud and virtualisation, broadcasters are not limited to using resources that are built, managed and maintained on their premises. They can leverage services via the internet, as well.

Having flexibility in managing audio and video is all very well, but broadcasters also need a mechanism for connecting different devices


Underlying technologies

A number of key enabling technologies will allow SDI workflows to work in IP. The simplest method of bridging this divide is to use SMPTE 2022-6, which encapsulates SDI in an IP stream, transporting video with embedded audio and ANC. This is a straightforward approach and fine for simple workflows in which there is little or no manipulation of the stream. In effect, it replicates what broadcasters do in SDI today.

Because frame accuracy is a big concern, broadcasters need a timing solution that will work for network-based data flows. Conventional sync and timecodes, and even NTP (network time protocol), do not have the accuracy needed when it comes to syncing IP streams in A/V applications in the way it is done in SDI. SMPTE 2059, which is the broadcast specification for PTP (Precision Time Protocol), supplies what is needed for highly accurate timing purposes.

Where there may be various independent audio sources, broadcasters can leverage AES67, which offers a way to transport audio over Ethernet and allows it to work with video. VSF TR-04 then takes the AES67 audio — plus SMPTE 2022-6 with its embedded video, audio and ANC — and leverages SMPTE 2059 for timing. Broadcasters can then work with discrete audio and embedded video and audio to create the desired output.

Generally regarded as the desired end goal, certainly for production environments, is VSF TR-03. This approach uses SMPTE 2059 and AES67 in the same way that TR-04 does, but it handles video (IETC RFC 4175) and ANC (IETF draft ANC291) separately.

By keeping the video, audio and ANC separate, and by maintaining the ability to sync them, broadcasters enjoy the flexibility necessary to manage many signals without the overhead of de-embedding and re-embedding. It is important to note that the VSF TR-04 and TR-03 technical recommendations are, at the time of writing, in the drafting phase of becoming SMPTE ST 2110. Though the standard has not yet been completed, vendors are not waiting to create products and ensure that broadcasters have interoperability.

Consequently, a broad range of products based on this standard will be available to the market in the near future. Managing flexibility Having flexibility in managing audio and video is all very well, but broadcasters also need a mechanism for connecting different devices, whether they are hardware or software in nature. SDI relies on knowing what connections can be made — matching inputs to outputs — in order for a system to work.

IP networks provide more flexibility, with the potential for making any source available to any compatible destination. To enable management of connections, NMOS (Networked Media Open Specifications) enables device services (type of inputs and outputs) to be registered and, in turn, allows devices to discover other devices on a network to which they can connect. This model does away with the need for specific connections for specific I/O and the need to know which devices are compatible, and it also enables use of a single medium for the transport of data and connection of devices. A device can register its I/O capabilities with a registration service or, in the absence of a registration service, use peer-to-peer discovery to find compatible devices to which it can connect.

In short, though it is unclear how long it will take to migrate fully away from SDI, the move to all-IP workflows is upon the broadcast industry, and even now the complexities of this transition are being resolved. The industry has shown unity and a desire to progress toward network-based solutions. Everyone benefits from all-IP infrastructure and the ability to go to cloud and virtualised solutions in the future. IP is an enabler of new business models, and it will drive business for users and solution vendors alike.