An audio frame is the fixed block of samples a codec treats as a single unit of encoding — for example 1024 samples for AAC, or a 20 ms chunk for Opus. It is the atom of compressed audio: the encoder analyses and packs one frame at a time, so a frame is also the granularity of latency (you can't send audio until a frame is full), of seeking (you can only cut on frame boundaries), and of packet loss (lose a packet, lose whole frames). Frame size is a deliberate tradeoff — shorter frames mean lower latency but worse compression efficiency and more overhead, which is why real-time and file codecs pick differently.
The book · Volume 4 of 7
Audio for Video: A Complete Guide to Sound in Video Products: From PCM and Codecs to Loudness, Accessibility, and Real-Time Voice Processing
Audio frame size sets the floor for codec latency and the step size for seeking and splicing, so it matters in calls and VOD alike. Volume 4 covers it in detail with PCM and sampling, the Opus and AAC codecs, and real-time voice processing, so you can pick an audio frame size for each path with the latency budget in mind. Written by Nikolay Sapunov, CEO at Fora Soft.
Trying to cut call latency and wondering whether a shorter audio frame will help?
Share your latency budget and codec setup, and we will recommend audio frame sizes per delivery path, with the latency each one adds. 250+ video products shipped since 2005.
