Remote sports commentary made easy with Spalk and AWS

This blog was coauthored by Michael Prendergast, CTO and Co-Founder, Spalk.

Introduction

A compelling sports broadcast is built on storytelling and commentators are the guides to these stories, helping viewers experience the narratives playing out on screen. Only recently have commentators enjoyed the flexibility of working remotely, allowing them to broadcast for leagues around the world instead of traveling from location to location. The simplified logistics of remote commentary also allows broadcasters to spend their efforts delivering more personalized, immersive, and localized content to sports fans.

In this blog post, we discuss how the Spalk Virtual Commentary Studio (Spalk VCS) helps sports broadcasters simultaneously grow audiences and reduce costs. We compare the solution to traditional commentary workflows, present a typical customer use case, and discuss key design considerations for remote workflows.

Traditional commentary workflows

In a traditional commentary workflow, a broadcast engineer sets up a commentary box, including microphone, talkback circuit, and perhaps a broadcast monitor. Commentators arrive and take their place in a media room or seat in the stands. The audio signal is then manually routed to the audio desk, mixed, synchronized, and uplinked with the broadcast feed for distribution to takers. The engineer then packs up the equipment at the end of the match and ships it to the next location.

Alternatively, a commentator can watch the broadcast feed in a dedicated location inside a broadcast center, which is called off-tube commentary (named for Cathode-Ray-Tube screens). While this still requires the commentator to travel, it removes the need to build and tear down the equipment.

Challenges

As any broadcast professional knows, adding commentary to a broadcast comes with many logistical challenges. Commentators are required to spend their game days (usually weekends) traveling. Technical staff are required on-site to set up and pack down. Broadcast equipment is bought, maintained, and transported to required locations. Managing the logistics of bookings, cancellations, availability, and payment of commentary talent across a league can be a full-time job. As a rights holder looks to engage new audiences with  different commentary languages, these challenges are prohibitive to all but the largest broadcasts.

The solution

The Spalk VCS allows broadcasters to add remote audio commentary to live broadcast content. Broadcasters can facilitate local language or world feed commentary that is cost effective, that reduces the monetary and environmental costs of travel, and is logistically simple, while preserving the highest audio and video signal quality.

The Spalk VCS natively supports almost all live commentary workflows, supporting up to five announcers on each audio track, and inserting up to 32 audio tracks on a single input stream.

Setting up a broadcast is as simple as:

1. Booking a commentator, either using in-house talent or selecting from Spalk’s Talent Marketplace.
2. Setting up a broadcast in the VCS, including details of the downstream destination(s).
3. Sending Spalk a live signal with clean “effects” audio (the audio without commentary mixed in).
4. Remote commentators sign in and are put live on-air.
5. (Optional) Spalk’s Live Production team manages the broadcast, promptly answering any commentator questions and ensuring signals are delivered successfully.

Signal workflow

Let’s explore the signal flows in a typical workflow for a broadcast customer:

1. Signal Acquisition
   The signal workflow in Spalk VCS starts with the acquisition of a broadcast feed. It sends the feed to Spalk cloud servers, where commentators and other production team members view a low-latency, low-bitrate proxy. The commentators (announcers) can talk to producers and/or the Outside Broadcast (OB) using talk-back channels.
2. Commentary Audio Return
   The HD audio return is delivered to Spalk cloud media servers using various techniques to ensure a reliable connection. The return audio is synchronized to the broadcast feed with lip-sync accuracy. Spalk constantly measures and compensates for any delay variance between the commentary and the input signal to ensure that the output audio remains synchronous with both international sound and video.
3. Remote Mixing and Monitoring
   The Primary Audio Engineer (A1) or producer can remotely mix the audio return with an International Sound (IS) bed, or pass through isolated commentary tracks for further mixing downstream.
4. Transport Stream Multiplexing
   The mixed tracks are multiplexed into the original broadcast Transport Stream and prepared for output. Spalk does not transcode the incoming video signal when inserting new audio streams. This maintains the original signal quality, preserving the highest possible video quality.
5. Output Distribution
   Once the Transport Stream has commentary added, the signal is delivered to downstream partners over the customer’s choice of protocol, including SRT, RTMP, Zixi, and RIST. For broadcasters who demand the highest reliability, Spalk integrates with AWS Elemental MediaConnect, providing end-to-end managed connectivity to Amazon Web Services (AWS). Together, this ensures reliable, secure, and low-latency delivery of the signal, allowing broadcasters to reach their audiences with high-quality content.

Customer use case: Sky Switzerland

Let’s explore how this workflow in a real-world environment.

On a typical game day, commentators Antoine Morin and Thierry Cros access the Spalk VCS from their homes in France and Italy, respectively, to provide French commentary for an Italian football match, to be broadcast in Switzerland. They can watch the live broadcast feed in real time and “talk-back” with the entire production team easily. The remote workflow provides the flexibility for Sky Switzerland to scale its commentary team up or down quickly and inexpensively, making experiments with new sports rights, languages and styles easy and risk free.

Screenshots

Commentator pre-live soundcheck

Virtual Commentator Studio (FullScreen)

Mixer Example

Output Dashboard

Key design considerations

There are several considerations that are top of mind for broadcasters including latency, reliability, and geographic proximity. Executing a successful broadcast requires that you have thought about each one, and designed your workflow accordingly.  The following are the considerations Spalk addresses in VCS.

Latency

Spalk’s platform minimizes latency as much as possible, a crucial factor for any live broadcast. Spalk workflows constantly measure and compensate for the return commentary audio delay, ensuring lip synchronization between audio and video outputs. It typically adds less than a second of additional delay in order to ensure this synchronization. The Spalk solution enables customers to deploy close to their users, reducing network hops, latency and improving the user experience. This is possible because of the AWS global network, which consists of 32 launched regions, 102 Availability Zones, and 450+ points of presence (at the time of publishing).

Reliability

VCS has reliability baked in, removing concerns about the unpredictable nature of public internet “last-mile” connectivity. Connections to the VCS get the best out of home and corporate internet connections. This is achieved using low-bitrate proxy streams to reduce bandwidth requirements and ensuring resilience using automatic retry request techniques (ARQ) and forward error correction (FEC) to recover packet loss.

One technique that differentiates Spalk’s solution is that users can connect redundantly using consumer networks and devices, such as a home internet connection and mobile phone hotspot. The network bonding technology combines multiple independent connections to create a more reliable connection to the Spalk VCS cloud. This means if one connection has issues, becomes congested, or totally drops out, there is no interruption to the end viewer. These techniques ensure the video and audio playback for commentators is error-free, even on internet connections that have substantial packet loss and jitter – up to 15% loss of first attempted packet delivery fully recovered without visual artifacts.

In addition to redundant connectivity, Spalk provisions redundant infrastructure across multiple Availability Zones for every broadcast. Even a few seconds of connectivity or service disruption can cause viewer complaints during a live broadcast, so Spalk adopted the architectural principles of redundancy and reliability in depth. Its redundancy and reliability were key factors to customers choosing Spalk to power over 20,000 broadcasts in 32 languages in 2022.

Spalk has advanced broadcast capabilities that set it apart in the remote production space. The platform supports SMPTE 2022-7 hitless switching, ensuring that signals arrive downstream without interruption, even in case of network or equipment failure at any point in the delivery chain. Additionally, Spalk guarantees PCR preservation, and SCTE-35 marker passthrough in constant bitrate transport streams, which means production companies can be confident signals will meet broadcaster expectations. The platform can also enable synchronization of multiple remote audio tracks into one transport stream, which is useful for distributing multi-lateral broadcasts to many regions of the globe.

Flexibility

The VCS supports most common broadcast formats, making it easy to get started no matter your current workflow. Supported formats include up to 4K video, interlaced and progressive, frame rates up to 60fps, bitrates up to 50Mbps, and ingesting MPEG-TS over SRT, Zixi or RIST, and signals over RTMP.

Overall, Spalk’s cloud-based platform and AWS services allow for a flexible and efficient signal workflow, making it easier for broadcasters to add broadcast-quality audio commentary to their live streams at a fraction of the traditional cost.

Summary

Discover the future of sports broadcasting with Spalk’s Virtual Commentary Studio, powered by AWS. Enjoy unparalleled flexibility, reliability, and scalability as you captivate audiences with personalized, localized, live sports commentary. Eliminate traditional commentary constraints and reduce costs without compromising on quality. If you would like to learn more, please reach out to Spalk for a demo at hello@spalk.co. To get started revolutionizing your live broadcasts, sign up for a free account today at www.spalk.tv.