Module & Plug-in

RX has been the industry leader in audio repair for years, and Post Production Suite 4 only adds to its legacy. The revolutionary new Dialogue Match, mixing powerhouse Neutron 3 Advanced, and multichannel Stratus 3D and Symphony 3D reverbs join RX 7 Advanced, Insight 2, and RX Loudness Control to bring you the most comprehensive post production software package on the market. Keyboard Shortcut Guide. The following table lists all default keyboard shortcuts in the RX Audio Editor. RX has options for defining your own keyboard shortcut commands. The column named “RX Shortcut Command Name” lists the name asociated with each default shortcut in the RX Audio Editor. Feb 18, 2016 As part of the RX Plug-in Pack, the De-clip plug-in can save vocal and dialogue tracks that were recorded too hot. Take a look at how to use De-clip in a session to fix clipped vocals.

Overview

De-clip repairs digital and analog clipping artifacts that result when A/D converters are pushed too hard or magnetic tape is over-saturated. It can be extremely useful for rescuing recordings that were made in a single pass, such as live concerts or interviews, momentary clipping in “perfect takes”, and any other audio that cannot be re-recorded.

De-clip will process any audio above a given threshold, interpolating the waveform to be more round. Generally, the process is as easy as finding the clipping you want to repair, then setting the threshold just under the level where the signal clips.

Controls

HISTOGRAM METER: Displays waveform levels for the current selection as a histogram. The histogram meter helps you set the Threshold control by displaying the audio level where the waveform’s peaks are concentrated. This usually indicates at what level clipping is present in the file. The longer the line for the histogram is, the more energy is present at that amplitude.
HISTOGRAM ZOOM CONTROLS: The histogram’s range can be scaled if you need a better view of your signal. Use the (+) and (-) buttons to scale your display and value resolution for the De-clip module. These buttons reduce (+) and/or expand (-) the range of the threshold slider and histogram. You may want to extend the histogram range when the clipping point is lower than what you can see on a histogram or if you don’t see anything on the histogram.
Note on histogram updating in the application vs. the De-clip plug-in
- In the RX Audio Editor, the Histogram meter updates based on selection: Select a section of the recording where clipping is prominent and De-clip will analyze the levels of the program material. If clipping is present in the selection, it will usually appear as a horizontal line in the histogram that extends all the way across the meter.
- In the De-clip Plug-in, the histogram runs as a real-time meter.
What is a histogram?
- A histogram is an analytical tool that displays how many samples are present at a given signal level over a window in time. The longer the line for the histogram is, the more energy is present at that amplitude.
- If a lot of energy tends to collect near the top and bottom edges of a waveform, that waveform is probably clipped and distorted.
THRESHOLD [dB]: Defines the level used for detection of clipped intervals. Generally, this should be set just below the actual level of clipping. To set the threshold, move the Threshold slider until it lines up with the place in the histogram just below where clipping is concentrated.
Understanding the Clipping Threshold overlays
- Adjusting the Clipping Threshold will display a blue line within the histogram and a gray line on the waveform itself (when the De-clip Threshold effect overlay). These lines indicate the audio information that will be considered as “clipping” by the de-clip algorithm.
Using the De-clip Threshold Effect overlay in the Spectrogram/waveform view
- By default, De-clip Threshold is enabled in the View > Effect Overlay menu.
- When enabled and the De-clip module is open, the De-clip threshold overly will be displayed in the spectrogram/waveform display.
- You can adjust the Threshold controls in the De-clip module by adjusting the Threshold overlay lines in the spectrogram display.
- You can use the mousewheel on the waveform amplitude ruler to adjust the threshold control values.
THRESHOLD LINK: Toggles the ability to adjust positive and negative clipping thresholds independently.
- When this option is enabled, you can adjust the positive and negative clipping Threshold controls independently. This is useful in cases where more clipping is occurring on one side of your waveform.
- You can also set asymmetric de-clipping thresholds directly from the waveform by toggling the lock box between the threshold controls on the waveform display.
SUGGEST: Calculates suggested threshold values based on the levels in your current selection.
QUALITY: Controls the interpolation processing quality. There are three quality modes in the De-clip module: Low, Medium, and High.
De-clip Quality mode notes
- Low quality mode processes very quickly.
- High quality mode processes slowly but is capable of achieving better results.
- In many cases you will find that Low quality mode gives you great results. To save time, always start by previewing the Low quality modes first. You can also use the Compare feature to try multiple modes and preview the results.
MAKEUP GAIN [dB]: Selects the gain to be applied to the selection after De-clip.
When to use the make-up gain control
- The De-clip process causes an increase in peak levels. The Makeup gain control can be used to prevent the signal from clipping after processing. It is also useful for matching the level after processing to unprocessed audio outside of the selection.
POST-LIMITER: Applies a true peak limiter after processing to prevent the processed signal from exceeding 0 dBFS.
- De-clip usually increases signal levels by interpolating signal segments “above” the clipping point, which can make the signal clip again if the waveform format offers no headroom above 0 dBFS.
- If the post-limiter is disabled, the restored intervals above 0 dBFS can be safely stored even without makeup gain as long as the file is saved as 32-bit float. Intervals above 0 dBFS will clip when played back through a digital-analog converter.

More Information

Suggestions for severe distortion

For certain situations, using the Deconstruct module to extract the noise components of the distortion can help remove additional artifacts beyond the clipped peaks in a waveform.
In cases where severe distortion is visible on the spectrogram, the Spectral Repair tool can be used to select those problem areas, and attenuate or replace them with undistorted audio.

Izotope Rx 4 Declip 2

Visual Examples

BEFORE & AFTER CLIP REPAIR

A waveform before and after clip repair. The after example (bottom) shows the original repaired waveform (faded) and the post-limiting waveform (bright).

Izotope Rx 4 Declip 3

UNLINKING THRESHOLD CONTROLS TO CURB ASYMMETRIC CLIPPING

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This problematic waveform (grey) shears off around −13 dB on only the positive side of the waveform (the histogram on the right shows the extra positive energy of clipped audio). Extra processing of the negative side would be unnecessary, so the Threshold controls can be unlinked to process above −13 dBFS on the positive side only. The resulting waveform is drawn in blue above the grey sheared peak.