Getting that pristine 4K HDR signal and Dolby Atmos to the homes around the country was an equally Olympian feat. Intending to deliver the live Olympics Primetime show, NBC needed a way for affiliates to integrate their local program feed with the live network national 4K HDR feed from Tokyo.

So, how do you distribute a high-profile event like the Olympics in 4K HDR when local TV stations don’t have the infrastructure to support it? The NBC network’s answer is a remarkable engineering solution developed and operated by its Operations and Technology division (O&T). It’s an idea that was born from the engineering team located at their main signal processing and distribution facilities in Centennial, CO. (near Denver) and Englewood Cliffs, NJ.

The result has been groundbreaking, allowing NBC to localize 4K HDR simulcasts in 52 of its owned and affiliated station markets – a first for a U.S. broadcaster.

Re-Imagining Network Signal Distribution
Like other US broadcast networks, NBC has been using a satellite-based distribution system to deliver HD network programming to its affiliates across the country for years. Their network delivery system is called SkyPath, which NBCU O&T has been working to upgrade.  

A core part of NBCU’s O&T strategy is to ensure that IP, 4K and immersive audio are all part of any major technology refreshes. To that end, O&T’s new SkyPath system is built on a full IP virtualized platform that meets these demands. NBCU’s O&T is funding the entire project—at no cost to the stations- laying fiber and equipping each station at the top 52 markets with a new video processing system that can integrate 4K HDR programming with its local content.

Making The Transition
Mike Harrell, VP of Distribution Engineering leads the team that designed and implemented this solution. As their existing satellite distribution footprint doesn’t have the bandwidth to distribute 4K signals, Harrell partnered with Comcast Business Services to establish dedicated redundant fiber paths into each station.

The new Enterprise backbone launched several months prior to the start of the Olympic Games (and only taking about a year between original concept and actual deployment) is working so well it will now serve the network going forward in a variety of applications.

“Comcast Business has been an invaluable link in the 4K distribution chain. Comcast’s ability to provide over 200 circuits, ranging from sub-1Gbps to 100 Gbps, connecting our strategic NBC locations with our affiliates, has given us capabilities far beyond what satellite can offer,” said Harrell.

The fully managed network is used to transport the live 4K HDR streams directly to a series of Harmonic XOS Advanced Media Processing units that are installed at each of the NBC stations. SCTE-35 messages embedded in these video streams provide instructions to each XOS edge device on when to switch between the live 4K HDR NBC feed and TV station local commercials, news break-ins, etc.

A special adapter feeds directly into a rights management tool, giving XOS the instruction for when and how to switch. This feature tightly synchronizes the signal switching— leveraging the network’s existing SkyPath satellite distribution platform to the station (NBCU patent pending). These signals from SkyPath provide the instructions for how and when to switch between 4K HDR NBC programming and local content using SCTE-104 frame accurate triggers. Harrell also indicates that these SCTE messages can be used for other future purposes as well. The end result was a system that ensured the three contribution streams (the HD stream, UHD and the affiliate stream) were always synchronized.

Building on NBC O&T specifications, the XOS encoding engine was adapted to power the UHD distribution system, all while using SMPTE 2110 and keeping the entire distribution and processing system in the IP domain.

In addition to relying on SCTE-35/104 messages to signal what frame to switch on, the NBC platform is also leveraging SCTE224/250 scheduling messages to ultimately tell XOS what to switch to when it receives a trigger. Leveraging these open standards in the entire distribution chain ensures interoperability between the many vendors used by NBC and their affiliates.

Core tenants of the platform include maintaining the affiliate’s ultimate control of the content making it to air and giving them the capabilities of 4K and Dolby Atmos. To enable this level of control, NBC provided stations with a method to directly interact with the platform using station automation and manual push-button overrides. With this capability, the affiliate can switch from the network provided 4K signal to the local station originated upconverted content at any time. This provides an additional means for the affiliate’s 4K and HD distribution to match all the time.

Immersive Audio Distribution
Faced with a new challenge to deliver 10 channels of immersive, phase aligned audio to stations, NBC investigated Dolby AC-4 (designed for emission) and cleverly configured it for use as a mezzanine level distribution codec. By stripping away the emission metadata, AC-4 could be leveraged to create a “clean piece of wire” between the network and its TV stations. Once received locally, the station’s XOS device transcodes the network’s AC-4 soundtracks from Tokyo, creating Dolby Digital+ JOC and making this available as a 10 channel (5.1.4) Atmos soundtrack on the station’s ABR stack. Local TV station audio is switched into the stream as 5.1. The overall result is a first of its kind, super-efficient process that ensures highest quality sound delivery to the audience.

Audio Description (AD)
In addition to the primary 10 channel Atmos soundtrack, NBC’s Stamford, Connecticut location provided audio description (AD) narration for the visually impaired. This audio was routed to a 30 Rock control room where it was combined with a mono version of the program soundtrack. Once properly mixed, it was distributed for the HD network and also sent out on an AAC Audio PID through the XOS system and made available on the UHD TV stations ABR stack for the network’s primetime show.

Standards Based Ecosystem
In order to ensure the platform’s longevity, NBC engineers took pains to develop their solution on standards-based protocols to facilitate interoperability across broadcast technology vendors.

“NBCU O&T built a system with an eye towards the future," said Grant McGilvray, NBC Engineering Architect. “Our mandate was to make the core of the station deployment 100% IP & industry standards based. We understand that not every station is IP ready today so we provided Riedel Commmunications SFPs to encapsulate local station SDI to SMPTE 2110." He continued, "As stations make the move to 2110, we will be able to support signals natively on our IP based platform.”

Monitoring Performance In The Cloud
NBCU Technical Operations provided end to end monitoring to ensure reliability throughout the Games. This new UHD distribution platform leverages the Amazon Web Services (AWS) public cloud for monitoring and real time analytics of all the affiliate streams. To do so, each station’s telemetry and video streams are brought into AWS. Utilizing log aggregation and parsing for telemetry, along with a Mediaproxy compliance system, NBC could analyze and record streams to observe switching characteristics and performance at scale.

“Indeed, this use of the cloud made the impractical monitoring of all the different simultaneous feeds, manageable,” Harrell said. “We realized that we either scale the infrastructure on prem. along with the ops and engineering teams to support it, or we leverage the cloud. All of our distribution and processing occurs where the origination resides, and the monitoring and telemetry analysis is done in the cloud.”

A Foundation For The Future
The results, both on and off the screen, have been stunning to watch. Behind the scenes the engineering team held their collective breath, watching and listening as the new IP distribution platform handled 17 days of Olympics programing—with all elements arriving the right place at the right time.