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Glossary · protocol

What is WebRTC?

WebRTC is the browser API for real-time peer-to-peer audio, video, and data. Powers Google Meet, Discord voice, WhatsApp Web calls, and most browser-based video chat. Different from streaming (one-way, buffered) — WebRTC is bidirectional, low-latency, lossy under network pressure rather than buffering.

Also called:web rtc · real time communication

WebRTC trades quality for latency. Where adaptive streaming buffers seconds ahead to maintain quality, WebRTC drops frames and reduces quality immediately to stay sub-200ms. That trade-off makes voice/video calls feel responsive but means YouTube's use of WebRTC is limited — it's for live streams where the latency matters, not VOD where buffering wins.

YouTube does use WebRTC for its low-latency live mode (the "ultra low latency" option in creator settings). Viewers in that mode see the stream within 1-2 seconds of broadcast. Standard live mode has 15-30 second latency because of buffering.

For YouTube downloaders: WebRTC content is harder to capture because it doesn't persist as discrete files — it's streamed frame-by-frame with no replay-able artifact. Once the call / stream ends, the data is gone unless one party recorded it.

Common questions

Why does YouTube's default live mode have 15-30 second latency?
Buffering for quality. The player needs ~15 seconds of pre-fetched content to handle network blips gracefully. Ultra-low-latency mode (1-2 second delay) trades that buffer for responsiveness — frequent quality drops on flaky networks.

Related terms

HLS (HTTP Live Streaming)

HLS (HTTP Live Streaming) is a streaming protocol developed by Apple.

DASH (MPEG-DASH)

DASH (Dynamic Adaptive Streaming over HTTP) is an open streaming protocol.

Streaming (vs download)

Streaming is the delivery model where the client starts consuming the file before it's fully downloaded.

VidPickr is a free, browser-based YouTube downloader. Every term in this glossary either describes how YouTube delivers video or why your downloads behave the way they do. Try the downloader →