DAGs, pre-signed URLs, and tiered CDN caching for video pipelines at scale

For engineering teams scaling beyond prototype stage, these patterns represent the baseline architecture required to handle thousands of concurrent uploads without saturating API servers or exploding CDN bills. The tiered CDN strategy — edge for viral, origin for long-tail, on-demand encode for unwatched — maps infrastructure spend directly to consumption economics, a principle that large-scale operators are increasingly formalizing. Watch how platforms instrument per-asset cache hit ratios and queue depth metrics to quantify the gap between naive all-edge delivery and this tiered model.

The cost pressure driving tiered CDN architectures is well-documented. Per a detailed CDN pricing analysis published by BlazingCDN (June 2026), five variables now account for over 90% of total CDN spend for video workloads: egress bandwidth, origin egress and shield fees, storage, request charges, and feature surcharges. The analysis notes that a 10,000-title library with five bitrate renditions and two packaging formats can exceed 500 TB of stored assets, and that just-in-time packaging — storing one mezzanine per title and packaging to HLS/DASH at the edge — can cut stored variants by 60–80%, though it requires compute at the packager layer. The article's on-demand encoding approach for unwatched content is an extreme variant of this same principle.

At the largest scale, operators are moving beyond tiered caching into hybrid edge architectures. ByteDance's HyperEdge system, presented at USENIX NSDI 2026, manages over 100,000 edge devices serving roughly 100 million daily users across Asia-Pacific and South America. The system handles only 10% of total user traffic through traditional CDNs, with edge devices absorbing the rest. ByteDance reports a 35% overall cost reduction compared to CDN-only delivery at 30 TB/s peak traffic — roughly $235M annually versus $360M. The edge network's unit traffic cost averages 55% of CDN rates, and a prefetching strategy exploiting diurnal traffic patterns virtually eliminates incremental CDN sourcing costs during non-peak hours.

The pre-signed URL pattern described in the explainer has become standard practice across the industry. System design references from Intervu.dev and HyperServe (both 2026) document the same architecture: API servers issue cryptographic tokens granting temporary direct write access to object storage, clients upload bytes straight to S3-compatible buckets, and the API server never touches the video payload. HyperServe notes it is migrating from POST-based uploads to direct-to-storage specifically because single large files tie up server connections and mobile devices produce increasingly massive files that cannot pass through an API gateway efficiently.