Where the delay comes from
With six-second segments and a three-segment buffer, a stream is already about 18 seconds behind before any other delay is added.
- Encoding and transcoding the feed
- Segment length: a player cannot fetch a segment until it is complete
- Player buffer: most players hold several segments before starting
- CDN propagation between origin and edge
Latency tiers
- Standard: about 10 to 30 seconds, with HLS or DASH
- Reduced: about 5 to 10 seconds, with shorter segments and a smaller buffer
- Low: about 2 to 5 seconds, with Low-Latency HLS or low-latency DASH
- Real time: under a second, with WebRTC, used for calls, auctions and betting
When it is worth it
Latency matters when viewers can compare the stream with something faster: a neighbor's broadcast television, a social media feed, a betting app or a chat. It matters little for a concert or a lecture watched alone.
Lowering it has a price. A smaller buffer gives the player less protection against network hiccups, so stalls become more likely, and low-latency delivery puts more requests through the CDN. Choose the lowest latency the content needs, not the lowest possible.
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