The actual maximum level of an audio signal including inter-sample peaks that occur between digital samples – measured in dBTP (decibels True Peak) to prevent clipping during digital-to-analog conversion, essential for broadcast loudness compliance and streaming delivery.
What is True Peak?
True Peak refers to the actual peak level of an audio signal, including peaks that can occur between digital samples. These inter-sample peaks can lead to clipping during D/A conversion – True Peak Limiting prevents this.
Basic Principle
| Aspect | Description |
|---|---|
| Definition | True maximum level |
| Problem | Inter-sample peaks |
| Measurement | dBTP (True Peak) |
| Goal | Clipping avoidance |
Sample Peak vs. True Peak
| Type | Description |
|---|---|
| Sample Peak | Sample values only |
| True Peak | Reconstructed signal |
| Difference | Up to +3 dB |
| Relevance | At high levels |
Inter-Sample Peaks
| Aspect | Explanation |
|---|---|
| Occurrence | Between samples |
| Cause | Signal reconstruction |
| Problem | Clipping in the DAC |
| Solution | Oversampling measurement |
Measurement
| Method | Description |
|---|---|
| Oversampling | 4x or higher |
| Interpolation | Calculate intermediate values |
| ITU-R BS.1770 | Standard |
| Meter | True Peak display |
Standards
| Standard | True Peak Limit |
|---|---|
| EBU R128 | -1 dBTP |
| ATSC A/85 | -2 dBTP |
| Netflix | -2 dBTP |
| Spotify | -1 dBTP |
Platform Requirements
| Platform | Specification |
|---|---|
| Broadcast TV | -1 to -2 dBTP |
| Cinema | Variable |
| Streaming | -1 to -2 dBTP |
| Podcast | -1 dBTP |
True Peak Limiting
| Limiter | Function |
|---|---|
| ISP Limiter | Inter-Sample Peak |
| True Peak Mode | In standard limiters |
| Oversampled | Higher precision |
| Lookahead | Predictive |
Software Tools
| Tool | True Peak Feature |
|---|---|
| iZotope RX | True Peak Limiter |
| FabFilter Pro-L | True Peak Mode |
| Waves L2 | True Peak Option |
| Nugen Audio | ISP Limiter |
Metering
| Meter Type | Description |
|---|---|
| PPM | Traditional, inaccurate |
| Sample Peak | Samples only |
| True Peak | Accurate display |
| Loudness Meter | Combined |
Workflow
| Phase | Activity |
|---|---|
| Mix | Leave headroom |
| Mastering | True Peak Limiting |
| QC | Verify measurements |
| Delivery | Check compliance |
Headroom
| Recommendation | Reason |
|---|---|
| -1 dBTP | Safe standard |
| -2 dBTP | More conservative |
| -0.1 dBTP | Only if necessary |
| Never 0 | Always avoid |
Sources of Error
| Problem | Cause |
|---|---|
| Clips | Insufficient limiting |
| Pumping | Too aggressive |
| False Reading | Incorrect metering |
| Rejection | Non-compliance |
Solutions
| Problem | Solution |
|---|---|
| Clipping | True Peak limiter |
| Over-Limiting | Less compression |
| Measurement Errors | Calibrated meters |
| QC Fail | Correction/Re-master |
Quality Control
| Check | Tool |
|---|---|
| True Peak | Analyzer |
| Loudness | LUFS Meter |
| Compliance | QC Software |
| Report | Documentation |
Best Practices
| Practice | Reason |
|---|---|
| Measure | Always True Peak |
| Headroom | Safety margin |
| Limiter Choice | True Peak capable |
| Document | For delivery |
Today
True Peak is an indispensable standard for professional audio production. With the dominance of streaming platforms and their strict loudness requirements, True Peak compliance is no longer an option, but a necessity. Modern limiters and metering tools make adherence easy, provided they are used correctly.