2020 - The Year Remote Became Reality
- With Dr. Ciro A. Noronha, Cobalt
Remote Head-End Management
Broadcast was headed toward remote operations for quite a while, but sometime in March, more precisely mid-March, what ‘could be’ became ‘what is’ - quite literally overnight. A pandemic unlike any seen in the past century shuttered shops, moved entire work forces to home-based, and forced the media and entertainment industry to embrace and adjust to operating remotely.
A global population looked to their TV’s and mobile devices as a lifeline to stay informed, educate themselves about rules and regulations, and sometimes for relief and amusement.
The situation called for head-ends to be as close as possible to unmanned. The ideal scenario, as well as the biggest challenge, was accomplishing every function and task without a physical presence and that included being able to control and test video paths, switch in/out-processing elements, and view and monitor every signal. This required low-latency, high-quality contribution-grade audio/video content to be transmitted over the Internet and monitored using consumer-grade devices such as phones, tablets or computers. Operators needed to be able to control the head-end and see the results from afar, in real-time.
Remote Head-End Management
In order to provide full remote head-end management, we need solutions for all the actions and functions performed by a local operator. These are:
- The equipment needs to be configured and monitored.
- Many functions require the operator to assess the resulting video (and possibly audio) content in real time. One good example of this is color correction: the operator may be tweaking some controls and need to “see” the results in real-time.
- Sometimes it is necessary to just look at the content using a consumer-grade device, such as a phone or tablet, for confidence monitoring.
- At times there is a need to add additional functions to a video path. For example, if an SDR feed is being ingested into an HDR workflow, it needs to be inverse tone mapped to HDR. A device with this capability will need to be brought online in the path.
- If there is a problem somewhere, one usual step to address this problem is to bring in test equipment. For example, a pattern generator to test a video path; an ancillary data monitor to see how closed-captions are coming in; and so on.
It turns out that all of these functions are already available in one way or another, and by carefully designing your head-end, you can make all of this happen today. This is illustrated below.
Let us look at each of the functions listed above and figure out how they can be accomplished:
- Remotely configuring the equipment: this is the easiest on the list. Virtually all equipment built in the last 20 years is managed through a network (with the possible exception of very simple throw-down boxes). Once the device has a network connection, it does not matter if it is in the same room as the operator or on the other side of the planet.
- Remotely watching video with very low latency: this is where the low-latency, contribution-grade transport protocols over the Internet come to the rescue. Proprietary commercial solutions have existed for many years. However, since 2018, there is a common specification called the Reliable Internet Stream Transport (RIST), described in more detail later. Cobalt encoders, such as the 9992-ENC and the 9223, support RIST natively. The same is true for Cobalt decoders, such as the 9992-DEC and the 9990-DEC. The 9992 compression line from Cobalt also includes low latency modes, where the intrinsic compression latency is minimized.
- Making the content available to consumer-grade devices: virtually all consumer-grade devices support the HTTP Live Streaming (HLS) protocol. Having encoders in the plant with support for HLS makes it possible to monitor any feed using a phone or tablet, from anywhere. HLS is a high-latency protocol, so it is not suitable for control, but is definitely adequate for remote monitoring. All Cobalt encoders have native support for HLS. The content can be served directly from the encoder itself using a built-in web server or pushed into an external web server to support a larger number of devices. Additionally, devices such as multi-viewers can be used upstream of the encoder to generate a mosaic comprised of a number of sources, allowing for simpler monitoring. The Cobalt 9971 multi-viewer is an ideal device for this purpose, being able to support up to 18 inputs (all with 4K capability) and two outputs (also with 4K capability).
- Adding functions to the video path: this is where an insightful head-end design can bring all the functions together. The “core” of the head-end should be a video router of sufficient capacity. All the incoming feeds terminate into this router, and all the outgoing feeds emanate from this router. This can be an SDI router for head-ends that use baseband SDI, or it can be a large switch for head-ends based on SMPTE 2110 flows. For SDI signals, the Cobalt 9942-RTR router is a good option. Processing elements, which operate “in-line” with a video signal, can be connected as generic resources to the video router, as indicated in the diagram below. This way, they can be pre-configured and “switched in” as needed. This becomes even more interesting if such processing elements are generic or multi-function - i.e., if the same element can be a frame synchronizer, color corrector, HDR processor, up/down/cross converter, audio processor, etc. For this function the Cobalt 9904-UDX-4K is an ideal choice, as it includes all of these functions and more, using a flexible licensing scheme. If you do not need 4K support but are looking for high-density HD processing, the Cobalt 9905-MPx is a 4-path device offering some of the same functions.
- Test and measurement: this can be done in a similar way as adding functions to the video path. Test and measurement devices either generate a test signal to be fed to a path that needs to be verified, and/or receive and analyze an incoming signal. The results of such an analysis are available through a network connection (e.g., via a web interface), and/or as an output video signal. By connecting test generators and analyzers respectively to inputs and outputs of the video router, these devices can also be brought online as needed. Devices that output results as a video signal could have this signal be available through the router, or directly on to some monitoring path. For signal generation, Cobalt offers the 9960-TG2-REF1, which is capable of providing two simultaneous video test signals, as well as audio test tones. For signal monitoring, Cobalt offers the 9978-ANC-MON ancillary data monitor. The 9978-ANC-MON has multiple inputs and can provide one single video output with the real-time monitoring results.
Transmitting Video Over The Internet
A headend is in the business of producing video. Therefore, a remote headend operator needs to see the video. As described before, there are two cases here:
- Low-latency, high quality video: if the operator is making changes to the video in real-time, they need very low latency, and very good quality to assess what is happening. This requires:
- Professional-grade equipment to receive the video from the Internet.
- Good-quality, high-speed Internet connection.
- Suitable protocol support for low latency.
- Monitoring-grade video: this is more for confidence monitoring, and it does not need to be low-latency or even at full resolution. The requirements are:
- Should work over a range of Internet connections, including cell connections.
- Should work on consumer-grade devices such as phones, tablets, smart TVs, and computers.
For low-latency, high-quality video, there is now an industry-standard protocol, the Reliable Internet Stream Transport (RIST), which includes:
- Tunable reliability / latency tradeoff to extract the best possible performance out of any Internet link.
- Ability to use multiple links in parallel.
- Interoperable: supported by a number of major vendors, including encoders, decoders, and gateways.
- Secure: built on top of DTLS, which is the UDP version of the TLS protocol used to secure Internet transactions. Both AES 128 and AES 256 modes are supported.
- Flexible authentication, to ensure that the endpoints are really who they claim to be. RIST is an integral part of a remote head-end, and is available in all Cobalt encoders and decoders.
For monitoring-grade video, the most common protocol available in consumer-grade devices is HLS. One advantage of HLS is that it can be served off a standard unmodified web server.
Additionally, many encoders with HLS support have a built-in web server, which simplifies deployment (as long as the number of clients is not too large). HLS represents a good compromise between ease-of-use and latency.
If a remote operator needs to have local equipment to monitor the signals, Cobalt now offers the BBG-1300-FR enclosure, which can take many of the existing Cobalt openGear cards into a portable chassis. This may be especially important when receiving a contribution-grade signal over the Internet using RIST.