An inter-sample peak is a peak in the reconstructed analog waveform that sits between two stored digital samples, so it never appears on an ordinary sample-peak meter. When the DAC's reconstruction filter draws the smooth curve through the sample points, that curve can overshoot the highest sample value, sometimes by a decibel or more. A file that looks safe at -0.1 dBFS in the sample domain can therefore clip the converter, or push a lossy encoder into distortion, on playback. True-peak (dBTP) meters catch these by oversampling before measuring. Inter-sample peaks are why mastering and delivery specs set ceilings below 0 — typically -1 dBTP — to leave room for the overshoot.
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
Inter-sample peaks are why a file that never touches 0 dBFS on a sample meter still clips after decoding or on a cheap DAC. This volume covers the inter-sample peak in depth with true peak, dBTP limits, loudness standards and lossy codec overshoot, so your masters stay clean after encoding. Written by Nikolay Sapunov, CEO at Fora Soft.
Files passing sample-peak checks but clipping later because of inter-sample peaks?
Send us a problem master and we will measure inter-sample peaks, set true-peak limiting and confirm the file stays clean after encoding. 250+ video products shipped since 2005.
