replaysystem

A replaysystem is a software subsystem that records and replays events from a session to support review, analysis, or broadcasting. It is common in video games, sports analytics, and security or research contexts. In video games, replays enable spectator modes, post-match analysis, and QA by reconstructing a past session.

There are two main approaches. Deterministic, input-based replays record player inputs, seeds, and essential state changes so the exact session can be reproduced, given deterministic physics and AI. Video-based replays capture rendered frames or streams and may include metadata for analysis; these are more resilient to nondeterminism but require more storage. Typical systems combine data capture (inputs, state deltas, timestamps), compression, and a playback engine that applies recorded events or replays frames. Some use separate logs for analytics alongside a video track.

Common features include precise playback controls, speed adjustment, camera control or scripted camera paths, and overlays showing events or metrics. Replays are usually indexed by match or session, enabling search and filtering. Privacy and security considerations cover sensitive data, cheating disclosure, and access controls.

Applications extend to other fields such as sports auditing and research, where replay data supports performance review and experimentation. Formats and implementations vary by platform and engine, but the core goal remains accurate, efficient, and accessible playback of a past session.