Understand ad insertion architecture for CDN and MediaTailor integrations - AWS Elemental MediaTailor
Request and response flow

Understand ad insertion architecture for CDN and MediaTailor integrations

This section explains the concepts and architecture of server-side ad insertion (SSAI) with content delivery networks (CDNs) for AWS Elemental MediaTailor. You'll learn how dynamic ad insertion and manifest manipulation work together to enable effective video monetization.

Server-side ad insertion (SSAI) with MediaTailor allows you to:

  • Insert personalized advertising into your video streams at defined ad break points

  • Target ads precisely based on viewer data

  • Eliminate the need for client-side ad insertion technology

When combined with a CDN, you can deliver these personalized streams to viewers with improved performance and scalability, enhancing your video monetization strategy.

The recommended architecture for ad insertion with a CDN positions the CDN between viewers and ad insertion, with ad insertion accessing content directly from your origin. This architecture provides the following benefits for both content delivery and video monetization:

  • Effective caching of content and ad segments

  • Reduced request load on MediaTailor

  • Improved delivery speed to viewers

  • Simplified URL management

  • Consistent delivery of personalized advertising across devices

In this recommended architecture:

  1. Viewers request manifests from the CDN

  2. CDN forwards requests to ad insertion

  3. Ad insertion requests content manifests from the origin

  4. Ad insertion requests ads from the ad decision server (ADS)

  5. Ad insertion personalizes manifests by replacing the ad markers (from the origin manifest) with URLs that point to targeted ad segments for the specific viewer (from the ADS)

  6. Ad insertion returns the personalized manifests containing ad segment URLs to the CDN, which forwards them to viewers

  7. Viewers request segments through the CDN

  8. CDN routes segment requests based on the segment type:

    • Content segment requests go to the content origin

    • Ad segment requests go to MediaTailor

This architecture ensures optimal performance while maintaining the security and flexibility benefits of using a CDN.

Diagram showing CDN positioned between client players and AWS Elemental MediaTailor Ad Insertion
Note

This flow varies slightly between VOD and live content. For VOD, manifests can be cached longer, while live content requires more frequent manifest updates to maintain stream continuity.

The key difference between VOD and live content caching:

VOD content

Set longer TTL values (minutes to hours) for manifests because they don't change frequently

Live content

Set shorter TTL values (seconds) for manifests to ensure viewers receive the most current stream segments

We don't recommend that you position a CDN between your content origin and AWS Elemental MediaTailor. Doing so can introduce several technical challenges:

Cache-key collisions

Configure your CDN to properly handle query parameters. This prevents MediaTailor from receiving incorrect manifests when requesting the same manifest with different query parameters.

Gzip compression issues

If you experience manifest parsing errors, ensure your CDN delivers properly formatted manifests to MediaTailor. Some CDNs may deliver corrupt gzip payloads that can cause parsing failures. If this occurs, you may need to disable compression between your CDN and MediaTailor while maintaining compression for cost savings elsewhere in your workflow.

Manifest freshness

For live streams, configure your CDN to deliver current manifests to MediaTailor. This prevents synchronization issues between content and ads.

Performance optimization

Minimize network hops and potential cache misses to reduce playback start-up times.

Cache management

Implement simplified cache invalidation strategies, especially for live content where manifests update frequently.

In this sub-optimal architecture:

  1. Viewers request multivariant playlists, media playlists, or MPDs directly from AWS Elemental MediaTailor.

  2. MediaTailor requests content manifests (multivariant playlists, media playlists, or MPDs) through the CDN.

  3. The CDN forwards requests to the origin server.

  4. The origin server returns multivariant playlists, media playlists, or MPDs to the CDN.

  5. The CDN forwards multivariant playlists, media playlists, or MPDs to MediaTailor.

  6. MediaTailor requests ads from the ad decision server (ADS).

  7. MediaTailor personalizes manifests by inserting ads into multivariant playlists, media playlists, or MPDs and delivers them directly to viewers.

  8. This architecture introduces additional latency, potential caching issues, and complicates troubleshooting.

Diagram showing CDN positioned between content origin and MediaTailor

Request and response flow

When implementing dynamic ad insertion with a CDN, configure your system to support this request and response flow:

  1. Configure your player to request multivariant playlists (HLS) or MPDs (DASH) from your CDN with MediaTailor as the manifest origin.

  2. Set up your CDN to forward all multivariant playlist, media playlist, and MPD requests to MediaTailor, including all query parameters and headers.

  3. Ensure MediaTailor can communicate with your ad decision server (ADS), passing along query parameters and headers.

  4. Configure your ADS to use query parameters to determine which ads to insert.

  5. Set up the CDN prefix on the MediaTailor playback configuration so MediaTailor can substitute CDN domain names for content and ad segment URL prefixes.

  6. Configure your CDN to forward personalized multivariant playlists, media playlists, and MPDs from MediaTailor to the requesting player.

  7. Set up your CDN to translate segment URLs, forwarding content segment requests to the origin server and ad requests to the Amazon S3 bucket where MediaTailor stores transcoded ads.

CDN terminology for ad insertion

Understanding these key terms will help you implement and troubleshoot your ad insertion CDN integration:

Origin CDN and edge CDN

Origin CDN: A CDN positioned between MediaTailor and your content origin. It caches content segments to reduce load on your origin servers. In a multi-CDN architecture, this is the first CDN layer that interfaces directly with the origin.

Edge CDN: A CDN positioned between viewers and MediaTailor. It delivers personalized manifests and content to viewers. In a multi-CDN architecture, this is the outermost CDN layer that interfaces directly with viewers.

CDN configuration terms

Cache behavior: Rules that determine how a CDN handles different types of requests. These rules include:

  • Caching duration settings

  • Origin routing configurations

  • Request handling parameters

TTL (Time To Live): The duration for which content remains valid in a CDN cache before it needs to be refreshed from the origin.

Cache key: The unique identifier used by a CDN to store and retrieve cached content. It typically includes:

  • URL path

  • Query parameters

  • Selected headers

Origin shield: An intermediate caching layer between CDN edge locations and your origin server. It reduces the number of requests to your origin.

Request collapsing: A CDN feature that combines multiple simultaneous requests for the same content into a single origin request.

MediaTailor-specific CDN terms

CDN content segment prefix: The CDN domain name that AWS Elemental MediaTailor uses when generating URLs for content segments in manifests.

CDN ad segment prefix: The CDN domain name that MediaTailor uses when generating URLs for ad segments in manifests.

For more information about CDN configuration with MediaTailor, see Set up CDN integration.

Note

These terms are consistent with those used in channel assembly documentation. For channel assembly terminology, see CDN terminology for channel assembly.