The transition from broadcasting to new open standards in IP is in full swing. There is still a lot of work to do and the next challenge is interoperability.
Carlos Pantsios Markhauser*
The Serial Digital Interface (SDI) standard has served for many years impeccably in TV productions around the world, using uncompressed video within broadcasting facilities. This standard made it possible for any type of equipment to be connected to other equipment that also supports this standard, regardless of the manufacturer. However, considerations such as the streamlining and simplification of current workflows in production, as well as their assignments and implementations of any kind have led to serious consideration of the benefits that an IP-based broadcasting infrastructure would offer.
The deployment of a new production process in the IP domain is basically an operation of controlling routing tables and location of signal processing resources, instead of the traditional rewiring of devices. In this way, it will be possible to prepare and assign signal processing devices over time, contained in a data center, in just a matter of minutes.
Pre-established configurations for studios, galleries and signal processing resources can be prepared in advance to dynamically meet individual production requirements and program formats. Devices connected to the network can serve as a pool of resources, being able to be shared efficiently, for example, allowing the interconnection of studios and galleries regardless of their location. This new flexibility opens the door to continuous adaptation and improvements in existing or future workflows.
However, this new world does not come for free. The principles of broadcasting, with separate control system and source signals sent to destinations, will change fundamentally in the IP domain, where the destination is responsible for signing up for the workflow that is currently available on the network.
The transition of the media industry and broadcasting from SDI to Internet Protocol (IP), as a fundamental means of moving signals between and through facilities, is already a reality today. It comes with the promise of greater system agility and scalability that can help broadcasters develop new business models and remain competitive.
Although there are no longer questions about whether or not this transition is necessary, there are very varied opinions about the timing and level of priority that broadcasters should give to this transition. However, a key impediment to the industry's push forward is the fact that multiple approaches to transition, which are in competition with each other, were introduced into the market recently further complicating an already difficult decision to make.
The Alliance for IP Media Solution (AFMS), a major industry association, strongly insists that the broadcasting industry must retain this approach of using a signal, a standard interface for video transmission, as the transition from SDI to IP takes place, in order to ensure that the widely deployed interoperability in signal transport continues.
IP is an inherently flexible protocol, but this same flexibility creates risk if technology suppliers are not fully aligned. The logic for common standards is obvious: interoperable solutions based on widely accepted and open standards have driven the growth of the industry and its enormous success for decades, accommodating current needs of broadcasters, preparing them for future advances.
An IP technology infrastructure, based on open standards, offers broadcasters maximum agility and flexibility to adjust their business models, capitalize on new revenue opportunities, and add new capabilities and services, without having to continually rebuild their workflows – while enjoying the freedom to build the best possible network.
When IP contribution video made its appearance, standards were agreed for signal transport in SDI over IP and most especially the SMPTE 2022 standard for transport and protection, and the JPEG and MPEG family of standards for compression. As a result, contribution IP networks can operate with a variety of equipment from different manufacturers.
As IP makes major inroads into studios, it becomes imperative for the industry to agree on standards that can provide the same flexibility and avoid getting stuck with particular vendors. Not only this, but since the IP has been placed to not distinguish between studios, campuses and remote locations, the standard that has been proposed for transportation within facilities will also want to become the de-facto standard for remote and contribution production.
Currently, the broadcasting industry has a solid IP roadmap, capable of delivering the same level of interoperability as SDI. The 74 members that make up the Video Service Forum (VSF), with the support of organizations such as the SMPTE and the EBU, have developed a series of recommendations to achieve an approach based on IP standards. The VSF approach has been tested, validated and supported by more than 30 broadcasting equipment suppliers and broadcasters who came together to find a solution that leads to true interoperability.
The roadmap established by the SMPTE/VSF represents a good path that media companies can follow for the adoption of IP technology.
The proposed standards were not developed by any particular vendor, and are the result of the union of diverse experiences of many specialists and connoisseurs of the media industry.
The VSF recommendations offer a progressive path to standards adoption by the broadcasting industry. These recommendations are summarized as follows:
SMPTE 2022-6
In the first instance, the VSF recommends the use of SMPTE 2022-6, which makes it possible for SDI signals to be transported over IP using the Real-time Transport Protocol (RTP).
The use of standard is widely deployed in contribution IP networks and is adopted as the baseline for interoperability. In addition, it is supported by numerous major industry vendors in the world. As SMPTE 2022-6 can carry any group of SDI signals, it can be used for both multiplexed signals (e.g. multiple videos and audios) and individual video signals.
As the payload of SMPTE 2022 is identical to that of SDI, it is seen as an effective way to create hybrid IP/SDI systems, which will continue to serve this purpose for the visible future.
VSF TR-04
The TR-04, which also forms the basis of the SMPTE 2110 (particularly the 2110-50), is a technical recommendation for the use of SMPTE 2022-6 for embedded audio video and AES67 for separate audio streams, the latter being a standard that is supported by many vendors. This is a first step towards the transport of the essence (individual signals) instead of the composite medium. AES67 effectively operates as the equivalent "discrete audio" in IP. This makes the TR-04 an ideal solution for systems that require both SMPTE 2022-6 compatibility and discrete audio flexibility.
VSF TR-03
The TR-03 is a technical recommendation that has an approximation based on the real essence (where each type of signal is transported individually but with synchronization information). This approach is better suited for a production environment than for a composite approach such as it makes audio processing easier, as it does not require de-embedding and re-embedding the signal.
The TR-03, which forms the basis of the SMPTE ST 2110, recommends the transport of media with uncompressed elementary currents over IP.
TR-03 encompasses a number of existing standards for mapping various essences over RTP, the standard protocol for real-time transport over IP. For video, the standard is RFC 4175, for audio it is the AES67, and for clock synchronization it is SMPTE 2059, which is built on top of the IEEE 1588 Precision Time Protocol (PTP).
RCF 4175 in particular brings the transport of video to the digital age, by transporting only the visible part of the video (active pixels) which reduces the volume of data to be transported.
VSF TR-03 is an improvement over VSF-TR-04 by replacing the SMPTE 2022-6 of the VSF TR-04 with an improved method of video data distribution. With the SMPTE 2022-6, all video current must first be unpacked and then the audio signal must be de-embedded from the SDI current. When processing is complete, the audio must be re-embedded in the SDI before the SDI signal can be repackaged. Using TR-03, the video is packaged using RFC 4175, which began in 2005 and is widely used today.
For THE VSF TR-03 audio, the AES67 is used, the standard accepted by audio equipment suppliers for high quality over IP. AES67 offers flexibility and capability beyond the limits of embedded audio. Only packets containing audio samples are required to be unpacked before being processed and then repackaged back into an IP stream. Not only is this process avoided pipeline and de-empution, but also the volume of packet traffic that needs to be routed to the audio processor is greatly reduced.
Likewise, the VSF TR-03 provides a well-thought-out solution for system over IP timing. The VSF TR-03 recommendation specifies the use of SMPTE 2059, which is built on the IEEE 1588 Precision Time Protocol. Because of this, with the VSF TR-03, a complete SOLUTION in IP will not require a separate distribution of the black burst reference.
SMPTE 2110
SMPTE began work in January 2016 to develop a set of standards specifying the transport, synchronization, and description of separate elementary streams of essence over IP for the purpose of live production, based on the VSF Technical Recommendations TR-03 and TR-04. The work is documented in SMPTE 2110.
After very successful demonstrations of IP technology, with the participation of multiple major equipment vendors, an important consensus appeared on what the new standard for IP should be. The new standard should represent a set of interoperable SMPTE rules for live production based on a stream of IP packets and compatible with commercial Ethernet technology.
The philosophy on which there was agreement was to move away from embedded signals and return to the use of discrete signals for each type of signal - video, audio, timing and auxiliary data. Switching was segregated by signal type. In this new world, the goal was to maintain the segregation of signals on the device but share transportation.
The following diagram summarizes the standards for media transport over IP in summary form.
Recently there were many competing concepts around what traditional and current signals should be considered? and how should this work?
When SMPTE first introduced ST 2022 part 1 and 2, it was given the name MPEGTS for sympathy. MPEGTS operated perfectly in the Ethernet LAN and WAN world.
Currently, the SMPTE released the 2110 standards family composed of 6 members. These standards harmonize perfectly with each other, and the SMPTE 2110 family as such is evolutionary. Every new standard that is integrated into the family harmonizes with all its members. Each member of the family is currently called essence. Fundamentally, all production devices will be able to originate and process all the essences of the 2110 (audio, video, timing and auxiliary data). These signals will be compatible with routing and switching equipment in Ethernet IP, of commercial type.
SMPTE ST-2110-10 is timing and synchronism, reference of master clock. It was previously called SMPTE 2059 and it was first created as IEEE 1588. It provides the accuracy of the frame time reference, required for live switching. All devices and networks will want to have the ST2110-10 as part of their signal complement.
SMPTE 2110-50 is the first member of the family. This is the SDI packaged as IP in SMPTE 2022 part 6. It includes only the video, without embedded audio or auxiliary data. This is what VSF TR-04 was promoting. This is the type of signal that, for example, will be presented at the output of the camera or at the input of a production switcher.
SMPTE ST 2110-30 is the audio that was previously known as AES67. Now where audio is no longer embedded in the SDI or removed during the encoding process to ST 2022, the essence of audio, AES67, is what audio production devices will want to generate and process.
SMPTE 2110-ST-40 is ancillary data. It was formerly known as SMPTE ST 291 or RTP (Real Time Protocol).
SMPTE ST 2110-20 is where future standards become interesting. When the essence of video changes from ST 2022 part 6 to IETF RFC 4175, leaning towards VSF and TR-03, it becomes necessary to ask, what will this mean for all previous devices that were based on the ST 2110-50? Will SMPTE 2110-20 want to be backward compatible with SMPTE 2110-50? Or is this an abrupt improvement of the system? Users will want to know if going to the ST 2110 will require another round of middleware converters or the gateway as common.
SMPTE ST2110-21 is the video package shaper. This is a new and positive addition. Moving media over networks puts a heavy load on the network and adding more bandwidth does not solve the problem. Traffic shaping or network optimization is a critical consideration when it comes to the design of an IP infrastructure.
IS-04 does not yet have an SMPTE 2110 designation. Here it is about the recognition and registration of production devices in the IP ecosystem. Ultimately this will make it easier for the signs to know where to go and the best route to follow to get there. When the real SDN (Software Defined Networking) arrives then is when the discovery and registration will be managed, but we are not there yet.
There is still a lot of standardization work on the way and the next challenge is interoperability. As can be seen, intensive work is being done on the smooth and effective transition from conventional production to IP production, which will not take long to become a technological reality in the world.
*Carlos Pantsios Markhauser is a Telecommunications Engineer and Master in Communications from the Simón Bolivar University, with a Specialization in Telecommunications in satellite and networks The George Washington University - School of Engineering & Applied Science, Specialization in Digital Telecommunications University of Colorado Boulder. He works as a full professor of postgraduate studies in the telecommunications schools at the Simón Bolivar Universities and the Andrés Bello Catholic University. In addition to professional consultant in TV projects and technical director at Mediax Gente de Medios.
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