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UTUVO Learn / Audio field guides

True Peak vs. Sample Peak: What the Meter Measures

Understand inter-sample peaks, dBFS and dBTP, then use a repeatable check to leave headroom in a finished audio master.

By UTUVO · Updated

Two measurements of the same signal

Sample peak is the largest stored sample value. True peak estimates the highest level of the reconstructed continuous waveform, which may occur between those samples. A true-peak meter uses interpolation to estimate that curve; it is not measuring the analogue output of your particular DAC.

The relevant measurement reference is ITU-R BS.1770, which covers programme loudness and true-peak level. Sample peak is normally expressed in dBFS and true peak in dBTP. The units help identify which question the meter answers.

Why a clean sample meter is not enough

Imagine dots on a curved line. The tallest dot does not have to sit at the highest point of the curve. That is why a file with samples below full scale can still have a reconstructed peak above it. The difference is signal-dependent; there is no fixed “add 1 dB” conversion between sample peak and true peak.

Lossy encoding can also change the decoded waveform. Measure a decoded preview of the encoded file when checking that path. The PCM master’s true-peak result does not predict every subsequent codec or playback process, and an over-range estimate does not prove every device will audibly clip.

A repeatable final-export check

  1. Export the approved programme, including the exact intended start and tail.
  2. Reset a true-peak meter and play or analyze the whole file. Save the maximum reading and measurement method.
  3. Compare it with the ceiling in the destination’s current delivery brief.
  4. If you change gain or limiting, make a new export and measure that version.
  5. Create a representative encoded preview, decode it for measurement and listen for damage to transients or dense passages.
  6. Keep the source master, encoded preview and results together under one revision name.

Do not insert a limiter solely because the true-peak and sample-peak numbers differ. First decide whether the measured peak exceeds a relevant limit. If it does, try an appropriate gain reduction and listen before choosing additional processing.

How much headroom to leave

Use the destination’s requirement and allow for the conversion you actually expect. Apple’s Digital Masters brief recommends at least 1 dB of headroom and encourages auditioning its AAC encode. That is useful guidance, not a guarantee that one setting makes every codec and service safe.

For an Atmos master, UTUVO QC places measurements in a delivery-preflight report. UTUVO Player Pro keeps loudness and peak context in the listening workflow. Keep the measurement label visible in your notes so the receiving engineer knows whether a number means sample peak, true peak or loudness.