The transition from broadcasting to the new open standards in IP is in full development. There is still a lot of work to be done and the next challenge is interoperability.
Carlos Pantsios Markhauser *
The Serial Digital Interface (SDI) standard has served impeccably for many years in TV productions around the world, using uncompressed video within the 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 a 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 a control operation of 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 studies, galleries and signal processing resources can be prepared in advance to meet dynamically with individual production requirements and program formats. Devices connected to the network can serve as a pool of resources, and can 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 free. The principles of broadcasting, with a separate control system and source signals sent to destinations, will change fundamentally in the IP domain, where the destination is responsible for signing up to the workflow that is available at that moment in the network.
The transition of the media industry and the broadcasting of the SDI to the Internet Protocol (IP), as a fundamental means to move signals between and through installations, is now a reality. It is accompanied by the promise of greater agility and scalability of the system that can help broadcasters develop new business models and remain competitive.
Although there are no questions about whether this transition is necessary or not, there are very different opinions on the timing and level of priority that broadcasters must give to this transition. However, a key impediment to the industry's push forward is the fact that multiple approaches to the 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), an important industrial association, strongly insists that the broadcasting industry should retain this approach of using a signal, a standard interface for video transmission, as the SDI transition is made to IP, to ensure that the widely deployed interoperability in signal transport continues.
IP is an inherently flexible protocol, but this same flexibility creates risks if the technology suppliers are not completely aligned. The logic for common standards is obvious: interoperable solutions based on widely accepted and open standards have driven the industry's growth and its enormous success for decades, by accommodating the broadcasters' current needs, achieving their preparation for future advances.
An IP technology infrastructure, based on open standards, offers broadcasters maximum agility and flexibility to adjust their business models, capitalize new revenue opportunities, and add new capabilities and services, without having to continuously rebuild their workflows - while they enjoy the freedom to build the best possible networks.
When the IP contribution video made its appearance, standards were agreed for the transport of the signal in SDI over IP and very specially the standard SMPTE 2022 for transport and protection, and the family of JPEG and MPEG standards for compression. As a result, IP contribution networks can operate with a variety of equipment from different manufacturers.
As IP makes major inroads into the studios, it becomes imperative for the industry to agree on standards that can provide the same flexibility and avoid getting bogged down with individual vendors. Not only this, but since the IP has been placed so as not to distinguish between studios, campuses and remote locations, the standard that has been proposed for transport within the facilities will also want to become the de facto standard for production. remote and contribution.
Currently, the broadcasting industry has a solid IP route sheet, 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 SMPTE and 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 broadcast equipment suppliers and by 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 recommendations of the VSF offer a progressive route for the adoption of standards by the broadcasting industry. These recommendations are summarized as follows:
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 the standard is widely deployed in IP contribution networks and is adopted as the baseline for interoperability. In addition, it is supported by numerous important industry vendors in the world. Because SMPTE 2022-6 can carry any group of SDI signals, it can be used for both multiplexed signals (eg, multiple videos and audios) and for individual video signals.
As the payload of the SMPTE 2022 is identical to that of the 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.
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 sellers. This is a first step towards the transport of the essence (individual signals) instead of the compound medium. AES67 effectively operates as the "discrete audio" equivalent in IP. This makes the TR-04 an ideal solution for systems that require both compatibility with the SMPTE 2022-6 and the flexibility of discrete audio.
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, as, for example, it makes audio processing easier, since 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 streams over IP.
TR-03 encompasses a number of existing standards for the mapping of several essences on RTP, the standard protocol for real-time transport over IP. For video, the standard is RFC 4175, for audio it is AES67, and for clock synchronization it is SMPTE 2059, which is built on the IEEE 1588 Precision Time Protocol (PTP)
RCF 4175 in particular brings the transport of the video to the digital era, 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 the VSF-TR-04 by replacing the SMPTE 2022-6 of the VSF TR-04 with an improved method of distributing video data. With the SMPTE 2022-6, all video stream must first be unpacked and then the audio signal must be de-embedded from the SDI stream. When the processing is completed, the audio must be re-embedded in the SDI before the SDI signal can be re-packaged. Using TR-03, the video is packaged using RFC 4175, which started from the 2005 and is widely used today.
For the VSF TR-03 audio, the AES67 is used, the standard accepted by suppliers of audio equipment for high quality over IP. AES67 offers flexibility and capacity beyond the limits of embedded audio. Only packages containing audio samples are required to be unpacked before being processed and then re-packaged back into an IP stream. Not only is it avoided, in this process, embutimiento and desembutimiento, but also greatly reduces the volume of packet traffic that needs to be routed to the audio processor.
Likewise, the VSF TR-03 provides a well-thought-out solution for system timing over IP. The VSF TR-03 recommendation specifies the use of the SMPTE 2059, which is built on the IEEE 1588 Precision Time Protocol. Due to this, with the VSF TR-03, a complete IP solution will not require a separate distribution of the black burst reference.
SMPTE started work in January on the 2016 to develop a set of standards that specify 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 emerged on what the new IP standard should be. The new standard should represent a set of interoperable SMPTE rules for live production based on an IP packet stream and compatible with commercial Ethernet technology.
The philosophy in 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. The commutation was segregated by signal type. In this new world, the goal was to keep segregation of signals on the device but share the transport.
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 the SMPTE first introduced the ST 2022 part 1 and 2, it was given the sympathy of the MPEGTS name. MPEGTS operated perfectly in the Ethernet LAN and WAN world.
Currently, the SMPTE released the 2110 family of standards 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 the 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 IP Ethernet, commercial type.
SMPTE ST- 2110-10 is timing and synchronization, master clock reference. 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 that the audio is no longer embedded in the SDI or removed during the process of coding the ST 2022, the essence of the audio, AES67, is what audio production devices will want to generate and process.
SMPTE 2110-ST-40 is ancillary data. It was previously known as SMPTE ST 291 or RTP (Real Time Protocol).
SMPTE ST 2110-20 is where future standards become interesting. When the video essence changes from ST 2022 part 6 to IETF RFC 4175, leaning towards VSF and TR-03, it is necessary to ask, what will this mean for all the previous devices that were based on the ST 2110-50? Will SMPTE 2110-20 want backward compatibility with SMPTE 2110-50? Or is it an abrupt improvement of the system? Users will want to know if going to ST 2110 will require another round of middleware converters or the common gateway.
SMPTE ST2110-21 is the video package shaper. This is a new and positive addition. Means moving over networks put a heavy load on the network and adding more bandwidth does not solve the problem. Traffic conformance or network optimization is a critical consideration when it comes to the design of an IP infrastructure.
IS-04 does not yet have a designation in SMPTE 2110. This is about the recognition and registration of production devices in the IP ecosystem. Ultimately this will facilitate the signals to know where to go and the best route to follow to get there. When the real SDN (Software Defined Networking) arrives then it 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 you can see, we are working intensively 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 Simon 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 postgraduate professor in telecommunications schools at the Simon Bolivar University and the Andrés Bello Catholic University. In addition to professional consultant in TV projects and technical director in Mediax Gente de Medios.