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VSF TR-03: An Elemental Step on the Path to IP

29 January 2016 - Tim Claman

ip-video-codecs.jpgOn October 21, 2015 the Video Services Forum (VSF) published Technical Recommendation TR-03. In the future, when we look back on our inexorable transition to IP, now in full swing, I believe TR-03 will stand as an important stepping stone on that path.

What is TR-03?

Simply put, the goal of TR-03 is to define a way to carry groups of audio, video, and ancillary data streams in real time over standard IP networks. TR-03 is essentially a mashup standard – it defines how to implement a specific combination of other existing web and media technology standards to achieve this goal.

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Fundamentally, TR-03 does away with the legacy SDI encapsulation (as specified in SMPTE 2022-6) in favor of elemental RTP streams. This means that, rather than encapsulating a media program’s audio, video, and ancillary data into one packetized stream, TR-03 sends each individual stream of data across the network independently. Receivers of these elemental RTP streams can consume only the streams that matters to them, and can accurately synchronize groups of streams by aligning them according to embedded time stamps.

How does TR-03 differ from SMPTE 2022-6?

TR-03 is more efficient, more flexible, and simpler to implement than SMPTE 2022-6.

  • TR-03 is less complex to encapsulate and decapsulate, making more efficient use of computing cycles in sending and receiving devices.
  • TR-03 carries only the active samples of audio, video and ancillary data. This makes TR-03 streams more network efficient than SMPTE 2022-6 streams, which contain significant payloads of null data (e.g. samples from the vertical blanking interval). In practice this can result in network bandwidth savings of up to 40%.
  • TR-03 carries video, audio, and ancillary as separate elemental streams, enabling receiving devices to consume only the streams that matters to them. For example, an audio processing device no longer needs to consume and unwrap an entire SDI stream, only to dump the entire video payload while extracting the audio streams.

TR-03 is Open and Extensible

At a time when many technology vendors are hastily pushing out their proprietary technologies and declaring them standards, TR-03 is a remarkably agnostic and open standard. The team that specified TR-03, the VSF Studio Video over IP (SVIP) Activity Group, referenced codified, open technology standards, avoiding proprietary technologies that may be encumbered by intellectual property rights (IPR) issues. Adopting technologies that are royalty-free encourages broad adoption, and ultimately lowers cost barriers for implementers and end-users.

The TR-03 standard is meaningfully prescriptive, incorporating a pragmatic set of interoperability profiles. But TR-03 is also extensible to essentially any image format. And while the TR-03 specification focuses principally on uncompressed video and audio, it leaves room for compression. In fact, a number of media companies and vendors, including SAM, have already implemented open, lightweight SMPTE VC-2 compression within TR-03 compliant elemental streams.

A New Approach to Standards

Beyond its technical merits, TR-03 is notable because it exemplifies a shift away from the traditional media technology standardization process. Rather than starting with a clean sheet of paper and inventing a new technology from scratch, the SVIP Activity Group adapted existing standards wherever possible, thus accelerating the process, reducing technical risk, and avoiding the creation of new IPR challenges. Further, in sponsoring the SVIP Activity Group to create TR-03, the VSF has demonstrated that it is possible to bring technologists from across the end-user and vendor communities, to work together in a constructive, fast-paced team, to deliver a tangible, practical recommendation.

SAM and TR-03

At SAM, we not only support TR-03, we are proud to have actively participated in its specification. During the development of the TR-03 standard, we began implementing TR-03, so that today we are very close to offering TR-03 compliance across a broad range of the SAM product portfolio. SAM is also an original member of the newly-formed Alliance for IP Media Solutions, the primary goal of which is to promote interoperable implementations of standards like TR-03.

Next Steps on the Path to IP

As with any technology standard, TR-03 will only be useful in the real world when it has been implemented in a consistent and interoperable manner. And, while TR-03 provides a solid foundation, it stopped short of addressing higher level issues like device discovery and registration.

The good news is that SAM’s TR-03 interoperability testing with other implementations has been very successful so far. And projects like the upcoming Advanced Media Workflow Association (AMWA) incubator provide venues for collaboration among the vendors and media companies that are paving the way towards an open, interoperable, converged IP future. Watch this space…

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