Same ad creative transcoded over and over (for each viewer session)
We have a working MediaTailor implementation for live HLS. We pre-fetch shortly before ad breaks (there are no set times for breaks in the live programming). We have our own CDN's in place for both ad and content segments.
Let's assume a new video ad creative is returned in an prefetch ad call. I would expect MediaTailor to transcode the ad to our various renditions, and those transcodings should persist for a period of time (hour, day?) and be used in future ad calls for viewers.
That's not what I see. It seems to transcode creatives for each individual viewer session. If the same creative is played later in that viewer session, no re-transcode is done. But if a viewer stops the session, creates a new session, we're back to square one and everything is re-transcoded. I can see lots of transcodings happening (that all are for the same creative) when I look at cloudwatch logs.
We're dealing with live HLS streams with 10K+ simultaneous viewers.
Is this expected behavior, or am I missing something or doing something wrong?
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asked 2 years ago226 views
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The behavior you're observing with AWS Elemental MediaTailor is not the expected or optimal behavior for ad insertion, especially for a live HLS stream with a large number of simultaneous viewers.
Typically, MediaTailor is designed to transcode ad creatives to match the encoding characteristics of the origin content. Once an ad is transcoded, it should be ready for use in subsequent requests, reducing the need for repeated transcoding of the same creative.
In an ideal scenario, when a new video ad creative is returned in a prefetch ad call, MediaTailor should transcode it to your various renditions and store these transcoded versions for a period of time. These stored versions should then be used for future ad calls across different viewer sessions, which would be much more efficient for a stream with 10,000+ simultaneous viewers.
The behavior you're describing, where the same creative is being transcoded for each individual viewer session, suggests that there might be an issue with how the ad caching or delivery is configured. This could potentially be related to how your CDNs are set up for ad and content segments, or there might be a configuration issue within MediaTailor itself.
To address this, you may want to consider the following steps:
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Review your MediaTailor configuration to ensure it's set up correctly for caching and reusing transcoded ad creatives.
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Check your CDN configuration to make sure it's not preventing the caching and reuse of transcoded ads.
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Verify that the ad decision server (ADS) is consistently providing the same ad creative identifiers for the same ads across different sessions.
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Reach out to AWS support for a detailed investigation of your specific setup, as they can provide tailored guidance based on your exact configuration and usage patterns.
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Monitor the MediaTailor metrics in CloudWatch to get more insights into the ad insertion and transcoding processes.
By optimizing this process, you should be able to significantly reduce the number of unnecessary transcodings and improve the efficiency of your ad insertion workflow for your large-scale live HLS stream.
Sources
How MediaTailor ad insertion works - AWS Elemental MediaTailor
MediaTailor FAQs
MediaTailor Features
answered 2 years ago
