Standards: Part 2 - Standards For Broadcasting & Deployment

This article gives an overview of the standards relating to production and transmission or playout. It prepares the ground for subsequent more detailed articles which will explore the following subject areas: ST 2110, higher bit rate codecs and profiles that are non-lossy, standards relating to exchanging material between different NLEs and Vƒx, and the AMWA workflow standards.


This article is part of our growing series on Standards. There is an overview of all 26 articles in Part 1 -  An Introduction To Standards.


Streaming and broadcast architectures are complex systems with many time-critical moving parts. If we view the architecture from different perspectives the challenges are easier to understand. If we examine the lifecycle of a media asset from concept to deployment and archiving, we see that only a part of the system is likely to require real-time performance vs. a file-based workflow.

The Traditional Approach

Conventional broadcasters are migrating to an IP based workflow by incrementally replacing the real-time critical parts of their SDI infrastructure with a functionally similar software solution. Currently, the industry is building systems that use SMPTE ST 2110, NMOS and their related technologies.

There are significant network bandwidth challenges to overcome with this approach. It is conceptually similar to the historical hardware-based solution and relies on being tightly synchronized in real-time. Achieving real-time low-latency performance is the major technical challenge to overcome with ST 2110 architectures.

The Modern Approach

The popular streaming services have always used entirely file-based workflows and storage. The streaming server transmits the file contents directly to the receiving devices. Performance is improved by adding Content Delivery Networks and Edge Servers but it is conceptually very simple.

These studios rarely deployed any SDI based architectures and have no need for ST 2110 to replace a classic analog TV architecture. They might still benefit from some of the features that NMOS offers with discovery and annotation of resources.

The architecture resembles a traditional IT system with file servers and commercial off the shelf (COTS) workstations.

The Challenge

Introducing new technologies and the imperative to give up long accepted traditions is always painful, stressful and prone to conflict.

Data delivery via an IP network is subject to delays and interruptions. This is partly due to the encoding latency as the source material arrives. The routing and transport are dependent on pathways that may change during the transmittal. Timely arrival is more likely if you are prepared to accept an occasional packet loss with UDP transport. Packets may arrive out of sequence due to the way the data is routed through the network. Buffering the data can alleviate this at the cost of additional delay by using TCP instead of UDP.

The asynchronous nature of IP networking is optimal for file-based transfers but makes real-time video delivery very challenging. This causes difficulty when implementing ST 2110 reliably across an entire enterprise.

A Hybrid Media Architecture

Perhaps there is a way to reorganize the architectural design to yield the benefits of both ideologies.

Create smaller self-contained pools of real-time sub-systems using ST 2110 where real-time performance is mandated. Then bridge them together with file-based IP solutions. This would split the problem into manageable pieces. A hybrid approach might therefore yield benefits as shown in this illustration of a media asset lifecycle.

Only the section inside the Real-Time shaded box is time-critical. The rest can exploit the benefits of an IP based network. Asset files are moved intact without worrying about how long it takes. Using standards-based file containers and codecs throughout will avoid unnecessary transcoding.

There is an integration challenge with the live feeds from an Outside Broadcast (OB). Provided the feed is continuous and glitch-free, we need not worry about the internal implementation. Synchronization for source switching is necessary but should introduce less than a frame of delay. Likewise, the playout system may need to buffer files that it fetches from the asset store so it can stream them out without interruption. Everything else downstream to the receiving devices works as it always has.

A smart IP enabled receiving device can also request content on demand. That content can be delivered from the same primary asset store. Optimize the downstream performance by using a Content Delivery Network (CDN) and edge serving buffers which are not shown on the diagram.

Arguably, an entirely COTS and IT based approach will be cheaper in the long run. There is a great deal of work in hand to leverage ST 2110 to successfully make the transition away from classic SDI based installations.

Metadata Quality

Reliability and performance are impacted by the quality of your supporting metadata. It underpins the entire collection of assets your enterprise owns. Use it to maximize the revenue opportunities. Metadata steers the production processes and broadcast delivery. Each stage is enabled by specific kinds of metadata.

Media asset collections are curated with a content management system. This typically describes the workflow from ingest to asset storage ready for playout. That is the core part of the production process but the asset exists well outside of that context and the metadata system should reflect the entire lifecycle.

Useful metadata can be created at the conceptual stage of a project and more insights can be gathered from the consumers playback device to analyze their level of engagement with the content and any advertising that you include with it. The user experience can also be steered by metadata that is created during pre-production. These aspects are rarely supported by a content management system. Embracing the entire lifecycle facilitates significant time and money saving automation.

Standards Applicable To A Typical Asset Lifecycle

An asset begins its lifecycle with initial planning and eventually arrives in the asset storage system for possible repeat viewing, syndication and archiving. Each stage should be facilitated by standards that support the workflow but they are incomplete. There are many opportunities for new standards to be created where there are none at present.

International Standard Audio-visual Number

This works like the ISBN numbers used to register books or ISSN numbers used for describing newspapers and magazines in search systems. It facilitates the distribution of your content when it is released for viewing. It also uniquely identifies a programme when searching the archives.

The ISAN numbers are defined by the ISO 15706 standard.

Register your media with an ISAN agent to get a unique ID number for each episode so that individual programmes can be found. Do this during the pre-production stage of your project - long before any content is created.

Your registration facilitates the collection of your copyright licensing revenues and recording music permissions for the audio content of your production. This process is evolving and growing in popularity and if you cannot locate a registration agency for your own country, there is alternative coverage via the ISAN organization.

What Do You Do When There Are No Standards?

You could write your own!

Your guidelines should be clear and unambiguous. This is most likely a specification for a data model which manages metadata or content. If you are describing a part of the lifecycle without formal standards, you could present this as a foundation for a standards body to build on. Here are the things you need to describe:

  • What is the purpose of your standard?
  • Where it is targeting in the workflow or lifecycle?
  • Does it rely on other pre-existing standards?
  • What are the inputs to it when it is a process?
  • What are the outputs?
  • Are there any controlling parameters or configurations?
  • What are the units of measure and ranges of values?
  • Are there profiles or preset configurations that work well together?
  • Define the default assumed values.
  • Anticipate the future and design your standard to be extended.
  • Allow for errors to be handled gracefully without invalidating the entire piece.
  • Provide usage examples. This is a major failing in international standards.
Conclusion

Many useful standards are created internationally and used world-wide. Others are only used within a geographical region. They will likely have counterparts in other territories. Some are defined by industry collaborations and special interest groups. Where there is no standard, create one specifically for your own enterprise. Perhaps it can be shared with other organizations. It might eventually become adopted as a widely used standard.

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