Managed Low-Latency Video Playback for OTT Live Streaming

Managed Low Latency Video Playback for OTT Live Streaming

Tech partner castLabs, in cooperation with AWS Elemental, enables end-to-end low latency live video streaming for Over-the-Top (OTT) services to securely achieve better-than-broadcast speeds with synchronized delivery to all viewers.

Video playback near the “live-edge” for events such as sports, news, betting, conferencing, second-screen interactions, and social casting can reduce the latency of content delivery, which benefits viewer satisfaction. However, technical barriers have traditionally made it difficult to reduce OTT video latency. Specific examples include the speed at which stream segments can be delivered and a client app’s ability to rapidly play them.

Engineering advancements now allow online services to move closer toward providing true live streaming experiences. To achieve this, a combination of AWS Elemental and castLabs technologies helps to minimize the camera-to-screen time gap.

castLabs’ PRESTOplay software development kits (SDKs) allow streaming services to create low-latency video apps for rich playback experiences. Through a wide range of ready-to-use features, live adaptive bit rate (ABR) streaming is possible across browsers as well as native apps for Windows, macOS, smart TVs, set-top boxes, game consoles, and Android and iOS devices.

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Low latency workflows combine on-premises contribution with cloud-based delivery. AWS Elemental Live provides on-premises video and audio encoding for linear TV broadcast and live streaming to new media platforms. AWS Elemental Media Services are managed cloud services that make it fast and easy to prepare, process, and deliver broadcast and multiscreen video. AWS Elemental MediaStore is an AWS storage service optimized for media. It offers the performance, consistency, and low latency required to deliver live streaming video content. Amazon CloudFront is a global content delivery network (CDN) service that securely delivers data, videos, and applications to viewers with low latency and high transfer speeds.

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  • Challenges
  • OTT live streaming delays hinder viewing experiences
  • Individual player applications must specifically be optimized for latency
  • Variable latency across OTT devices results in unsynchronized playback for each viewer
  • Solutions
  • AWS Elemental Live and castLabs PRESTOplay enable better-than-broadcast latency
  • Cross-platform low-latency playback built into all PRESTOplay SDKs
  • Manage latency behavior with PRESTOplay SDK technology across devices
  • Benefits
  • Improve viewer experiences and satisfy consumer expectations
  • Quickly deploy low-latency enabled apps without coding from scratch
  • Achieve consistently similar latency for all viewers
castLabs Workflow

Player applications created with PRESTOplay are interoperable with video workflows built with Amazon Web Services. Used in conjunction with AWS Elemental Live, AWS Elemental MediaStore, and Amazon CloudFront, OTT services can easily provide quick live streaming playback. In many scenarios, content can be delivered using HTTP with less latency than conventional broadcast workflows.

PRESTOplay apps can attain sub-5 second end-to-end latency playback with MPEG-DASH and HLS formats. Clients also have the ability to manually override standard stream specs such as the 3-segment latency for HLS.

Optimal Latency Chart

PRESTOplay SDKs provide a common API framework to enable identical playback behavior over different devices. Configuring low latency across player applications is easy with parameters that include unique optimizations for latency performance, such as:

  • A set delay time to maintain playback from the live-edge
  • Catch-up modes that enable dynamic live-edge tracking to determine player performance if playback position falls behind a given threshold such as when a buffer under-run occurs and the player must wait for segments. These catch-up modes include ‘speed-up’ where there is a slightly increased playback rate until reaching the live-edge or ‘seek’ where playback jumps straight to the live-edge.

For instance, an OTT provider could set 3 seconds of live-edge latency with playback speed-up occurring if the playback position drops behind 4 seconds. In this situation, the speed-up would continue until the 3 second latency is reached.

Low-latency live streaming additionally creates new opportunities for interactive content such as game shows, wagering, and social engagement. In these use-cases, synchronizing latency across multiple devices becomes valuable for viewers to have a similar chance to answer questions, wager, or provide other responses. PRESTOplay enables device synchronization through API parameters that require each player app instance to continually remain within the same latency boundaries.

Digital Rights Management (DRM) is often necessary to keep content secure during delivery. This is especially important when delivering premium content such as live sports. DRMtoday is a cloud-based solution from castLabs that offers extensive licensing and access control features. DRMtoday API integration with AWS Elemental Live video processing provides customers with secure, scalable, standards-based live workflow protection with encrypted just-in-time packaging for MPEG-DASH, HLS, and other formats. Customers gain access to major studio-recognized DRM systems including Google Widevine, Microsoft PlayReady, and Apple FairPlay Streaming for secure playback across a broad range of consumer devices. Built on reliable multi-region AWS infrastructure, users automatically connect to their least-latency node to minimize license turnaround time and to further mitigate against video stream delays.

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DRMtoday in combination with PRESTOplay also enables playback features including key rotation for live events, Common Encryption (CENC), and where available, hardware-based DRM security for high-quality stream renditions.

The interoperability of PRESTOplay with AWS Elemental Live and AWS Elemental MediaStore lets video providers simplify processing and delivery of high-quality low-latency video streams. Complemented by DRMtoday API integration with AWS Elemental Live, end-to-end secure and scalable low-latency video streaming is easily achievable.

"Multiple points along the video delivery chain and on each playback platform must be optimized for low latency to be realized. Our decade-long experience building robust multi-platform player and DRM technologies when combined with technology from AWS Elemental provides an ideal workflow solution to make managed low-latency experiences easily achievable today.” Michael Stattmann, CEO castLabs


  • Description
  • PRESTOplay streamlines development of low-latency live streaming apps
  • PRESTOplay manages synchronization of latency across viewers
  • DRMtoday built on AWS enables protected content licensing in the cloud
  • Features
  • Low latency functionality built into player SDKs and ready to use
  • Common API for simple configuration of live-edge stickiness behavior
  • Fast multi-DRM licensing and key rotation
  • Benefits
  • Lower costs and accelerate time to market
  • Enable similar low-latency experiences however viewers wish to watch
  • Enable premium content with speedy stream start times for all screens

Visit to discover how castLabs and AWS Elemental can enable your low-latency streaming video experiences.