Comprehensive Technical Glossary

This glossary provides definitions for key technical concepts, video codecs, container standards, and architectural components used in RUSEON Core.

1. Video & Streaming Terminology

NAL Unit (Network Abstraction Layer Unit): The atomic packet unit of H.264/H.265 video bitstreams. Contains either compressed slice data or parameter sets.
SPS / PPS / VPS: Sequence, Picture, and Video Parameter Sets. Metadata NAL units that define video resolution, profile, color space, and decoding parameters.
GOP (Group of Pictures): A sequence of video frames starting with a KeyFrame (I-Frame) followed by predictive frames (P-Frames, B-Frames).
KeyFrame (I-Frame / IDR): Instantaneous Decoder Refresh frame. A fully self-contained video image that does not reference preceding or subsequent frames.
Transmuxing (Zero-Transcoding): Repackaging compressed video/audio packets from one container format (e.g. RTSP RTP) into another (e.g. fMP4, WebRTC SRTP, HLS TS) without decompressing pixel data.
WHEP (WebRTC HTTP Egress Protocol): Standardized IETF protocol (RFC draft) using simple HTTP POST requests for WebRTC SDP offer/answer signaling.
Glass-to-Glass Latency: Total elapsed time from light hitting the camera sensor to the corresponding pixel rendering on a client monitor.

Fragmented MP4 (fMP4): ISO BMFF video container format composed of sequential moof (movie fragment metadata) and mdat (media data) boxes. Crash-resilient by design.
RingBuffer: In-memory circular buffer storing recent video frames. Enables zero-copy frame distribution and instant KeyFrame backfill for new viewers.
Page Cache Thrashing: A Linux kernel condition where sustained 24/7 file writing floods RAM with dirty pages, evicting active application memory and causing severe I/O latency.
POSIX_FADV_DONTNEED: Linux system call used by RUSEON Core to immediately evict flushed video pages from kernel RAM cache after disk writes.
BadgerDB: An embedded, persistent, pure-Go Key-Value database based on the Log-Structured Merge-tree (LSM) architecture with separated Value Log.