S4C Freely Live Workflow

Executive Summary

S4C built a production-ready live TV pipeline on AWS Elemental Media Services to launch its channel on Freely. The workflow combines live encoding, packaging, server-side ad insertion (SSAI), and CDN delivery, while supporting multiple audio tracks including Welsh audio description (AD). The architecture also integrates FreeWheel for ad decisioning and uses Amazon CloudFront for scalable delivery.

Key Industry Developments

• A local broadcaster implemented a production-ready pipeline for Freely using AWS Elemental Media Services.
• The workflow combined packaging, ad insertion, and delivery components across AWS Elemental MediaPackage v2, AWS Elemental MediaTailor, FreeWheel, and Amazon CloudFront.
• The pipeline delivered multiple audio tracks, including English, Welsh, and Welsh audio description (AD), indicating support for accessibility-oriented audio variants in the live distribution chain.
• The ad workflow used SSAI with FreeWheel acting as the Ad Decision Server (ADS), establishing a server-side approach to ad stitching and decisioning for the live stream.

Real-World Use Cases

• Live encoding and handoff into packaging: An ABR CMAF output from AWS Elemental Live was used as the input to AWS Elemental MediaPackage v2, illustrating a workflow where live encoding produces an adaptive bitrate CMAF signal that is then packaged downstream.
• SSAI with external ad decisioning: The live pipeline incorporated server-side ad insertion using AWS Elemental MediaTailor, with FreeWheel providing ad decisions as the ADS, representing an SSAI workflow where ad selection is delegated to an external decision server.
• Multi-track audio delivery for viewers: The distribution included English, Welsh, and Welsh AD audio tracks, demonstrating a live workflow designed to carry multiple language and accessibility audio variants through to playback.
• CDN delivery to connected TV viewers at scale: Amazon CloudFront delivered the live content to Freely viewers, indicating a CDN-based distribution layer designed for scalable live streaming delivery.

Why It Matters

A single live workflow can require coordinated handling of encoding outputs, packaging inputs, ad insertion, and delivery. In this implementation, the ABR CMAF output from AWS Elemental Live served as a defined interface into MediaPackage v2, providing a concrete example of how live encoding and packaging can be chained in a production pipeline. The inclusion of SSAI with FreeWheel as the ad decision server shows how ad decisioning can be integrated into a server-side workflow rather than relying on client-side ad insertion. Multi-track audio delivery, including Welsh audio description, demonstrates that accessibility-oriented audio variants can be carried through the same live distribution architecture. CloudFront’s role in delivering the live content to Freely viewers at scale highlights the use of a CDN layer as the final distribution component for connected TV audiences.

Sources

• https://aws.amazon.com/blogs/media/s4c-on-freely-how-a-local-broadcaster-delivered-a-complex-live-tv-workflow-with-aws-elemental-media-services/