Toistopuskuri

Toistopuskuri (fi. toisto meaning "repetition" and puskuri meaning "buffer") is a data buffer used in playback systems to temporarily hold audio or video data before it is presented to the user. Its main purpose is to decouple the delivery rate of input data from the playback rate, allowing smooth rendering even when data arrives irregularly due to network variability, disk access, or processing load.

In practice, toistopuskuri is typically implemented as a circular or ring buffer managed by software components such as media players, streaming clients, or game audio engines. As data arrives, it is written into the buffer; the decoder and renderer read from the buffer at a steady pace according to the playback clock. The system monitors the buffer level to prevent underflow, which causes stalling, and overflow, which can waste memory or require eviction of data.

Key design considerations include buffer size, which trades startup latency against resilience to jitter; adaptive buffering that adjusts size based on observed conditions; and synchronization with timestamps and clocks. Some implementations use double- or multi-stage buffering to minimize glitches, and may employ mechanisms to recover from underflow without major interruptions.

Common contexts for toistopuskuri are audio and video playback in media players and streaming applications, live broadcasting, VoIP and other real-time communications, and game audio systems.

As a Finnish term, toistopuskuri is used in technical literature and documentation relating to multimedia systems, streaming, and data processing. See also buffering, ring buffer, jitter buffer, streaming.