# True Peak Safe Limiter

Limit a master to a chosen true-peak ceiling (-1, -2, -1.5 or -0.3 dBTP) with a measure-limit-verify loop: FFmpeg’s lookahead limiter is driven below the ceiling by an inter-sample margin, and the result is re-measured with the BS.1770 oversampled meter until the true peak genuinely sits under target.

> Canonical page: https://elysiatools.com/en/tools/audio-true-peak-safe-limiter

- **Category:** Media

- **Keywords:** true peak limiter, dbtp, inter-sample peak, oversampling, bs.1770, ebur128, alimiter, ffmpeg, mastering, streaming loudness, ceiling, -1 dbtp, -2 dbtp, limiting, pre-encode headroom

## Overview

A true peak is the maximum of the reconstructed continuous waveform, measured in dBTP with 4x oversampling per ITU-R BS.1770 — real program material routinely hides 0.5 to 1.5 dB of inter-sample peak above the loudest stored sample, so a plain sample-peak limiter set to the ceiling still ships overs. This tool runs a closed loop: the input true peak is measured with FFmpeg’s ebur128 (peak=true, the BS.1770 Annex 2 oversampled method); if it is already under the ceiling the file is simply converted losslessly; otherwise FFmpeg’s lookahead alimiter is applied with its threshold set BELOW the ceiling by an inter-sample safety margin (the limiter only sees samples, so the margin reserves room for the peaks between them). The output is then re-measured with the same oversampled meter, and while any true peak remains above the ceiling the margin grows in 0.5 dB steps and the pass repeats — the loop only accepts a verified reading, never the limiter’s own claim. The limiter always runs with auto-level off (otherwise it renormalises the output back up and defeats the ceiling) and lookahead delay compensation on. Output is written as lossless PCM (32-bit float WAV or 24-bit FLAC) so the tool itself adds no codec overshoot; measure and limit after any sample-rate conversion, per AES TD1008. Ceiling presets follow current delivery practice: -1.0 dBTP for streaming and EBU R128 broadcast, -2.0 dBTP where heavy lossy encoding follows (Amazon Music, Netflix, low-bitrate HE-AAC), -1.5 dBTP conservative streaming, -0.3 dBTP for lossless/hi-res releases. Integrated loudness is reported before and after so the loudness cost of the limiting stays visible.

## Inputs

- **Master audio** (file)
- **True peak ceiling** (select)
- **Custom ceiling (dBTP)** (number): e.g. -1.2
- **Inter-sample safety margin (dB)** (number): e.g. 1.0
- **Attack (ms)** (number)
- **Release (ms)** (number)
- **Output format** (select)

## When to use

- Preparing masters for streaming platforms and EBU R128 broadcast specs requiring a strict -1.0 dBTP ceiling.
- Mastering content destined for aggressive lossy encoding on services like Netflix or Amazon Music that require -2.0 dBTP headroom.
- Eliminating inter-sample peaks (ISPs) from high-energy audio tracks prior to lossy AAC or MP3 distribution.

## How it works

- Measures the input file's true peak and integrated loudness using FFmpeg ebur128 with 4x oversampling per ITU-R BS.1770.
- Passes the audio through untouched if it is already below the ceiling, or applies FFmpeg's lookahead limiter below the ceiling using an inter-sample safety margin.
- Re-measures the output true peak and iterates in 0.5 dB margin increments until the true peak reliably complies with the chosen ceiling.
- Exports the final compliant master in lossless 32-bit float WAV or 24-bit FLAC while reporting before-and-after integrated loudness.

## Use cases

- Streaming Master Compliance: Enforce a verified -1.0 dBTP ceiling on stereo masters to prevent clipping during platform transcoding.
- Lossy Codec Headroom Prep: Apply a -2.0 dBTP ceiling to audio tracks headed for high-compression AAC or Opus encoders.
- Lossless Archival Packaging: Catch rogue inter-sample spikes on high-resolution masters using a subtle -0.3 dBTP safety margin.

## Frequently asked questions

### What is the difference between sample peak and true peak (dBTP)?

Sample peak measures discrete digital sample values, while true peak calculates the reconstructed analog waveform using 4x oversampling to catch inter-sample peaks.

### Why does the tool use an iterative verification loop?

Standard peak limiters only monitor sample values, so the tool iteratively re-measures with BS.1770 oversampling and adjusts safety margins until compliance is verified.

### Which ceiling preset should I choose for standard music streaming?

The -1.0 dBTP preset matches standard delivery recommendations for major streaming platforms and EBU R128 broadcast delivery.

### Will limiting my master change its integrated loudness?

Yes, peak limiting slightly reduces integrated loudness depending on the peak reduction, and the tool reports loudness values before and after processing.

### What happens if my file is already below the selected ceiling?

The limiter is bypassed entirely, and the file is losslessly packaged into your selected output format without altering the audio samples.

## Related tools

- [Lossy Codec Preview Compare](https://elysiatools.com/en/tools/audio-lossy-preview-compare): Hear and measure what streaming does to your master: encode to MP3, AAC or Opus at real streaming bitrates, decode back, and compare loudness shift, true-peak overshoot and headroom against the original — the Apple Digital Masters round-trip audition as a report plus downloadable preview files.
- [MP3 to High Quality](https://elysiatools.com/en/tools/mp3-to-high-quality): Re-encode MP3 with a higher bitrate or VBR setting (for compatibility or delivery)
- [Audio Change Bitrate](https://elysiatools.com/en/tools/audio-change-bitrate): Re-encode audio to a new bitrate while keeping the same format
- [Audio Add Silence](https://elysiatools.com/en/tools/audio-add-silence): Add a specified duration of silence to the start or end of an audio file
- [Air Band Enhancer](https://elysiatools.com/en/tools/audio-air-band-enhancer): Brighten dull vocals or masters with a high air shelf plus an exciter that synthesizes new top-end harmonics — the Aphex Aural Exciter architecture built from FFmpeg.
- [Album Loudness Matcher](https://elysiatools.com/en/tools/audio-album-loudness-matcher): Match a batch of tracks to one target loudness the way album gain works: one gain for the whole record keeps intentional inter-track dynamics, hybrid mode only tames outliers, per-track mode flattens everything.
- [Audio Ambience Loop Generator](https://elysiatools.com/en/tools/audio-ambience-loop-generator): Extract the background ambience/room tone from a fragment and generate a seamless loop of any target length.
- [Batch Audio Normalize](https://elysiatools.com/en/tools/audio-batch-normalize): Normalize multiple audio files to a target peak level with consistent volume across the batch

## Samples

- [Copyright-Free FLAC Audio Samples](https://elysiatools.com/en/samples/flac-samples): Lossless FLAC audio samples for testing and development, mirrored from MP3 set with nature sounds and meditation music
- [Copyright-Free MP3 Audio Samples](https://elysiatools.com/en/samples/mp3-samples): Collection of royalty-free audio samples for testing and development purposes including nature sounds, meditation music, and ambient audio
- [Copyright-Free WAV Audio Samples](https://elysiatools.com/en/samples/wav-samples): Uncompressed PCM WAV audio samples for testing and development, mirrored from MP3 set with nature sounds and meditation music
- [Copyright-Free Raw PCM Audio Samples](https://elysiatools.com/en/samples/pcm-samples): Raw PCM s16le audio samples featuring nature ambience and relaxing music for waveform, playback, and conversion workflows

## Related content

- [Audio Master Lossy Codec Preflight and Delivery Checks](https://elysiatools.com/en/hubs/audio-master-lossy-codec-preflight-and-delivery): Preview a finished master through lossy encoding, inspect decoded peak and loudness changes, adjust only when necessary, and verify the exact final MP3, AAC or Opus delivery file.