Startup time (video startup time, or time to first frame) measures the delay between a viewer pressing play and the first frame rendering. It is one of the most consequential QoE metrics: studies repeatedly show that every extra second of startup increases the chance the viewer abandons before watching.
It is the sum of many steps - entitlement and license fetch, manifest download, the first segments, and the initial buffer fill - so reducing it touches the whole stack: faster license/manifest paths, a conservative initial rendition for a quick start, CDN proximity, and low-latency techniques. Startup time and rebuffering are the two QoE numbers most directly tied to engagement and, for paid services, churn.
The handbook · 7 volumes
Fora Soft Video Engineering Handbook
Every extra second of startup time raises the chance a viewer gives up before the first frame. The seven volumes cover the video stack; for startup time start with Volume 3 on players, ABR start rungs, and CDNs, then Volume 1 on keyframes and encoding, with manifests and DRM license timing in Volume 2. Written by Nikolay Sapunov, CEO at Fora Soft.
Videos taking several seconds to start on some devices?
We will measure startup time across your apps and send a breakdown by stage with the fixes that cut it most. 250+ video products shipped since 2005.
