Zoom / Google Meet — Notes

Functional

• Multi-party real-time A/V.
• Screen share, chat, reactions, polls.
• Cloud recording + transcripts.
• PSTN dial-in / dial-out.
• Webinar mode (many viewers, few presenters).
• Optional E2E encryption.

Non-functional

• Glass-to-glass latency < 150 ms (ideal).
• Tolerate 5–10% packet loss without disconnect.
• 99.99% signaling availability.
• Global presence — meet near both participants.

Capacity

• Peak: 30M concurrent participants (Zoom 2020).
• SFU per box: 1–5k participants; 1000s of boxes.
• Per call bandwidth: 1.5 Mbps HD up + downstream × N.

Schema

• meetings(id, host_id, start, end, region, codec, e2e_flag)
• participants(meeting_id, user_id, join_ts, leave_ts, device)
• recordings(meeting_id, segments[], transcript_ref)

Trade-offs

• SFU is the default; balances cost and quality.
• Server-side recording requires plaintext → tension with E2E.
• Simulcast doubles encode cost but enables per-receiver quality.
• TURN cost is real — fall back only when STUN fails.

Refs

• Zoom architecture blog & talks; Google Meet QUIC migration.
• WebRTC standards (RFC 8825 + RFC series).
• Jitsi Videobridge (open-source SFU).
• MLS Messaging Layer Security RFC.
• ByteByteGo "Design Zoom", Alex Xu Vol 2.