Inter-sample peaks — the hidden problem
Digital audio is sampled — typically 44.1 or 48 kHz. Between any two samples, the actual analog waveform passes through values that aren't recorded.
Most of the time those in-between values are smaller than the sample peaks. But if your audio is brick-walled (limited hard against 0 dBFS), the analog reconstruction can spike above 0 dBFS, even though every sample reads exactly 0.
These hidden spikes are called inter-sample peaks. They cause clipping when the audio is converted to analog (in your speakers, headphones, DAC) or when it's encoded to a lossy format like MP3 or AAC.
How true-peak is measured
A true-peak meter upsamples the audio (typically 4×, sometimes 8× or 16×) and measures the peak of the upsampled signal. This reveals inter-sample peaks that a regular sample-peak meter misses.
The result is reported in dBTP (decibels true-peak). A track that hits 0 dBFS sample-peak might read +0.6 dBTP — meaning its actual analog peak is 0.6 dB above 0 dBFS.
Why it matters for streaming
When Spotify, Apple Music or YouTube encode your master to AAC/MP3 for streaming, the lossy codec can push values higher than the original PCM. If your master sat right at 0 dBFS sample-peak, the encoded version may clip — and listeners will hear distortion.
Industry standard is to leave at least 1 dB of true-peak headroom. Spotify, Apple, YouTube, Tidal and most others recommend −1.0 dBTP as a maximum. Amazon recommends −2.0 dBTP for safety.
How to control true-peak
Use a true-peak limiter as the last plug-in on your master bus. Most modern limiters (FabFilter Pro-L 2, Ozone Maximizer, Waves L2 Ultramaximizer, Ableton Limiter with TP enabled) have a true-peak ceiling option.
Set the ceiling to −1.0 dBTP (or −2.0 for extra safety) and the limiter will catch inter-sample peaks before they leave your DAW.
Frequently asked
What's the difference between sample-peak and true-peak?
Sample-peak only sees the digital samples. True-peak upsamples to estimate the analog peak between samples. They can differ by 1-2 dB on heavily limited audio.
Does true-peak only matter for lossy encoding?
Mostly, but also for analog conversion. Cheap consumer DACs can clip on inter-sample peaks too. Leaving 1 dB of headroom protects every playback chain.
Why −1.0 dBTP and not 0 dBTP?
The 1 dB margin gives the lossy codec room to round up without clipping. Streaming services chose −1.0 as a safe industry standard.