Real-time & Media

HLS is the dominant streaming format for live and VOD on Apple devices, CDNs, and most broadcast workflows. M3U8 text manifest + segmented media is the canonical chunked-file envelope pattern.

Real-time features — chat, live dashboards, collaborative editing, notifications, trading UIs — run on WebSockets. Every serious app eventually needs them.

MP4 is the dominant video container on the web and in MSE players. Box hierarchy, codec vs container distinction, and fragmenting (fMP4 for HLS/DASH) are essential for media engineering.

WebM is the default output of browser MediaRecorder and a common delivery format for open web video. EBML element structure differs from MP4 boxes.

H.264 remains the most widely supported video codec. Distinguish codec (H.264 bitstream) from container (MP4/WebM) when debugging playback, transcoding, and MSE SourceBuffer codec strings.

MP3 remains the most universally recognized audio format. ID3 tags (metadata envelope) prepended/appended to the frame stream are a classic header-envelope pattern.

AAC is the default audio codec for YouTube, Apple ecosystems, and most HLS/DASH streams. Distinguish ADTS-framed AAC from AAC inside MP4 boxes.

DASH is the open-standard counterpart to HLS for adaptive video. MPD manifest structure + fMP4 segment layout is how Netflix-style streaming works outside the Apple ecosystem.

The go-to protocol for server-push without WebSocket complexity. Used for AI/LLM streaming responses, live notifications, and real-time dashboards over plain HTTP.

Video calls (Meet, Zoom web), voice calls, peer-to-peer file transfer, and collaborative tools. The browser API surface for real-time A/V communication.

NAT traversal is why WebRTC calls fail. ICE is how browsers find a working path between peers. Know it when debugging call connectivity failures.

STUN is how WebRTC discovers the public-facing address for peer-to-peer connections. Every WebRTC deployment needs a STUN server.

~15-20% of WebRTC calls require TURN relay because both peers are behind symmetric NAT. Without TURN, those calls fail silently.

FLAC is the standard lossless audio format for archival and audiophile distribution. Metadata block chain is a clean example of typed extensible headers.

For gaming, live collaboration, and real-time data where WebSocket's TCP head-of-line blocking matters. Runs over QUIC so multiple streams don't block each other.

WebRTC media is always encrypted. DTLS-SRTP is the protocol that does it. Know it when troubleshooting media security negotiation or DTLS handshake failures.

Video players (YouTube, Netflix, Twitch) use MSE for adaptive streaming. Required if you build a custom media player or do in-browser video processing.

Required for any platform that distributes premium or licensed video content (streaming services, pay-per-view, licensed media).