Digital audio is a series of samples, but what comes out of a speaker is a smooth, continuous waveform rebuilt from those samples. Between two samples, that rebuilt wave can rise above both of them. Those hidden highs are called inter-sample peaks, and the highest one is your true peak.
Why it matters
A master whose samples never pass 0 dBFS can still have true peaks above it. That's usually harmless inside your DAW, but converters in cheap devices can clip on those peaks, and lossy encoding (MP3, AAC, Ogg) makes it worse: encoding reshapes the waveform slightly and often raises the peaks. The result is a crunchy, brittle distortion you never heard while mixing.
How true-peak meters work
A true-peak meter oversamples the audio — typically 4× — to estimate where the continuous waveform goes between samples, and reports the highest point in dBTP (decibels true peak). It's an estimate, but a very good one.
What ceiling to use
- −1 dBTP is a safe, widely recommended ceiling for streaming masters.
- If your master is very loud (well above −14 LUFS), leave a little more room — around −2 dBTP — because loud masters tend to gain more peak level when encoded.
- A true-peak limiter (or a look-ahead limiter set a little lower) is the tool that enforces the ceiling cleanly.
SoundBooster's peak meter shows sample peak, true peak and clipping per channel, and the mastering limiter lets you set the ceiling directly.