v7.0 (2024-09-07)
3.0MiB
v7.0 (2024-09-07)
2.8MiB
v7.0 (2024-09-08)
3.9MiB
v7.0 (2024-09-07)
5.9MiB
v7.0 (2024-09-07)
5.6MiB
v7.0 (2024-09-07)
5.3MiB
v7.0 (2024-09-07)
5.0MiB
v7.0 (2024-09-07)
5.3MiB
(all platforms)
About
x42-limiter (aka dpl.lv2) is a look-ahead digital peak limiter based on Fons Adriaensen's DPL-1. It is intended to be used as final step to avoid clipping when mixing or mastering, but can also be used on individual tracks as well. It comes in mono and stereo variants, the stereo version applies the same gain reduction to both channels.
Latency is 1.2 ms, rounded up to the nearest multiple of 8, 16 or 32 samples depending on sampling frequency. This amounts to 56 samples at 44.1 kHz, 64 samples at 48 kHz, and twice those values for 88.2 or 96 kHz.
The limiter can operate in digital-peak and true-peak mode. This only affects the detection mechanism (key input is 4x oversampled), the live signal itself is not directly affected.
Inter-sample peaks in a sine-wave.
The red line (top and bottom) indicates the digital peak, corresponding to the sampled data (blue dots). The actual analogue sine-wave (black line) exceeds this level. Peaks like these are called intersample peaks, or true peaks.
Screenshots
User Interface
The control knobs respond to mouse click and mouse-drag movements:
- Click + drag on knob: up/left to increase, down/right to decrease
- Shift + click: reset to default
- Right-click on knob: toggle current value with default, 2nd click restore
The Ctrl key allows for fine-grained control when dragging or using the mouse-wheel on a knob.
Hovering the mouse over label below a control displays a tooltip with information.
Parameters
- Input gain: This sets the gain applied before peak detection or any other processing. The range is -10 to +30 dB in steps of 0.2 dB.
- Threshold: The maximum sample value at the output. The range is -10 to 0 dB in steps of 0.1 dB. The limiter will not allow a single digital-peak sample above this level.
- True Peak (dBFS/dBTP): Toggle threshold unit between digital peak, and true-peak. When enabled the limiting process will detect true-peaks and reduce them below the given threshold.
- Release time: This can be set from 1 ms to 1 second. The limiter allows short release times even on signals that contain high level low frequency signals. Any gain reduction caused by those will have an automatically extended hold time in order to avoid the limiter following the shape of the waveform and create excessive distortion. Short superimposed peaks will still have the release time as set by this control.
Display
The level and gain reduction display, shows a range from -10 to +20dB with ticks every 5dB.
The meter at the bottom shows the peak signal level after input gain and relative to the threshold which corresponds to the green to yellow transition. The scrolling waveform above the meter shows the gain reduction history, with the range being displayed for every 50 ms segment of the signal.
Acknowledgments
dpl.lv2 is based on Fons Adriaensen's zita-audiotools.