Low-latency live streaming

Design a low-latency live-streaming platform for interactive broadcasts (creator + chat) supporting 10M concurrent viewers on a single popular stream and sub-3s glass-to-glass latency so the streamer can react to chat in real time. The long tail is millions of small streams. Design ingest, transcoding for live, the distribution path, and how you reconcile sub-3s latency with the CDN scale needed for 10M viewers.