A granule is an MP3-specific subdivision of a frame: each MP3 frame at standard sample rates contains two granules of 576 samples, each independently quantized and coded, sharing the frame's header and a pool of bits via the bit reservoir. The concept rarely matters until you try to edit MP3 sample-accurately — because frames carry encoder delay and padding and reference shared bits, you can't cleanly cut an MP3 on an arbitrary sample the way you can with PCM. Modern codecs use cleaner frame structures, so 'granule' is mostly a legacy term you meet when wrangling MP3 timing, gapless playback, or trimming.
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
A granule rarely matters until you try to cut an MP3 at an exact sample and the edit lands a few hundred samples late. This volume explains the granule within audio frames, packets and codec structure, with encoder delay and priming, so you can do sample-accurate trims and splices on legacy files. Written by Nikolay Sapunov, CEO at Fora Soft.
Trimming MP3 files sample-accurately and running into granule and encoder delay offsets?
Tell us about your editing or ad-insertion flow and we will give you a sample-accurate trimming approach that handles granule boundaries and priming. 250+ video products shipped since 2005.
