Free Lossless Audio Codec (FLAC)
FLAC is the standard lossless audio format for archival and audiophile distribution. Metadata block chain is a clean example of typed extensible headers.
What It Defines
Lossless audio format: `fLaC` magic, metadata blocks (STREAMINFO, VORBIS_COMMENT, PICTURE, etc.), then compressed audio frames. Each metadata block has type, length, and payload. MIME type: `audio/flac`.
Canonical (Normative)
Convenient (Practical)
Publishes web platform specs including CSS, accessibility, security policies, Service Workers, Web App Manifest, and many browser APIs. Also maintains some versioned HTML/DOM specs.
Related Specs
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.
Opus is the codec for real-time audio on the internet. WebRTC mandates it; Discord, Zoom, and most VoIP apps use it. Understanding bitrate, FEC, and frame sizing directly impacts audio quality and bandwidth.