The first Media over QUIC CDN: Cloudflare

Original Article ↗ Hacker News Discussion ↗

MoQ, WARP, and Streaming Formats

  • WARP is a media format candidate for MoQ, built around CMAF/fMP4 segments, so it can share caches and remain backward-compatible with HLS/DASH during rollout.
  • MoQT deliberately separates transport (fan-out, priorities, groups/tracks) from media details, allowing different streaming formats and use cases to coexist on the same relay/CDN infrastructure.

MoQ vs WebRTC and Transport Behavior

  • QUIC/WebTransport can drop media on streams or datagrams, giving WebRTC-like congestion behavior.
  • Current issue: common QUIC congestion controllers favor throughput over latency, unlike WebRTC’s GCC; server-side tuning can help but browser changes are also needed.
  • Latency is largely under receiver control: players must build their own jitter buffers and choose when to render frames.

QUIC, NAT, and Infrastructure

  • For client–server, QUIC has no special NAT traversal problem: 1 RTT to connect; main issue is environments that block UDP.
  • P2P over QUIC in browsers is considered impractical today; WebRTC+TURN/ICE remains the path there.

CDN / Relay Architecture and Load Balancing

  • Public MoQ relay uses GeoDNS today; anycast plus QUIC preferred-address is seen as the better long-term option but cloud anycast+UDP is limited.
  • Others warn that anycast can be fragile at low QPS, while DNS steering has caching trade-offs but more control.

Performance and Goodput

  • Some discuss research showing lower goodput/bitrate with HTTP/3 vs HTTP/2; consensus is that QUIC implementations aren’t yet as tuned as TCP, especially for very high bitrates and low loss.
  • Hardware offload and better GSO/GRO-style optimizations are seen as key future improvements.

Browser Support and Bugs

  • WebTransport works in Chrome and Firefox desktop; Safari has partial support behind a flag and is still buggy.
  • Firefox has known WebTransport and HTTP/3 quirks; people share bug links and debugging tips (DoH, HTTPS DNS records, Alt-Svc behavior).

Demos, UX, and Rendering Issues

  • Many report the MoQ demos as “instant” and extremely low-latency, praising “click-to-streaming time.”
  • Several mobile users see fast-moving horizontal black lines when using canvas-based rendering; others see aspect-ratio issues. Suspected causes include browser rendering bugs and canvas vs <video> behavior, with some discussion of power usage and autoplay blocking.

Other Use Cases and Features

  • MoQ could support low-latency multiplayer/game networking by mapping game data onto MoQT objects/tracks and using relays for fan-out.
  • Some ask about multicast; responses argue CDNs already approximate multicast at L7, and true IP multicast likely only helps the very largest events or P2P.
  • Multiple publisher bitrates/simulcast and receiver-driven track switching are already possible; subgroup-based and sender-side adaptation need more experimentation.

Ecosystem, Tooling, and Meta

  • Third-party implementations (e.g., MediaMTX integration with WebTransport + native QUIC) show early ecosystem growth.
  • Questions arise about adoption in OBS/YouTube and relationship to existing APIs like WebRTC, WebCodecs, and MSE.
  • One thread branch debates HN’s “original source” rule regarding this blog vs the Cloudflare announcement; moderators ultimately restore the blog post, with recognition that it adds distinct technical content and tooling.