Features of the paid version of ClipShifter
The paid version of ClipShifter adds three additional features: oversampling with double processing, multiband frequency controls, and mid/side processing. These controls enhance the versatility of ClipShifter. Specifically, these controls make ClipShifter more desirable for final audio processing or for more strategic saturation effects.
A problem with many audio plugins is aliasing artifacts. This occurs with certain algorithms that apply non-linear processing to the audio signal. It is especially prevalent at lower sampling rates (e.g., 44100 or 48000). The result is that additional audio content is present at unintended frequencies. This can sound like undesired distortion or harmonic ringing. In general, ClipShifter minimizes aliasing effects through the use of its internal clipping algorithm; however, certain situations can produce unintended audio artifacts.
Oversampling is a process that greatly minimizes alias effects. The general process is to increase the samplerate internally, process the audio, filter out all of the alias artifacts, and then down convert the samplerate. This occurs internally and the audio host application is not aware that any samplerate conversion is occurring.
ClipShifter has settings for 2x, 4x, and 8x oversampling. This means that audio is internally being processed at the samplerate of the track, times the multiple (e.g. 4x of a 44100 sample is up-converted to 176400 samples per second). The result is that most of the aliasing artifacts do not occur once the samples are filtered and returned to the original samplerate before passing to the host application.
Since oversampling involves processing 2, 4, or 8 times the amount of data as well as additional filtering, oversampling can tax the computer’s CPU. Depending on the computer, this may appear as a CPU usage of 2 to 4 times the amount when compared with oversampling disabled.
Clicking the oversample button cycles through the various options (i.e. Off, 2x, 4x, 8x).
Please note: Oversampling involves filtering high frequency content of the audio. Depending on the frequency content of the source and the settings of the multiband frequency control, audible difference can exist between the different settings. This can sound like a slight decrease in the very top end of the audible spectrum (i.e., -3dB above 17kHz).
A byproduct of using Oversampling with ClipShifter is that output signals can sometimes exceed the Threshold levels set by the Initial and End Threshold controls. This is an inevitable effect of upsampling, waveshaping/clipping, and downsampling. The end result is that peaks may go +1 to +2dB above the Threshold, depending on input gain, audio levels, and Threshold settings. This is undesirable in certain situations (e.g., when ClipShifter is being used as a brickwall limiter). The Double button is designed to remedy this particular problem.
When Double is engaged, the signal is processed through the clipping algorithm an additional time after oversampling. The same Harmonics and Clip Shape settings are during the Double processing; however, the entire signal is processed, regardless of the multiband frequency settings or mid/side settings. When Harmonics and Clip Shape are set to 1.0, the Double processing keeps the output within the Threshold settings.
The Double setting can also be used creatively. The result of processing an oversampled signal a second time through the algorithm will change the harmonic content of the distortion. This can be used in conjunction with the Clip Shape and Harmonics controls to alter the harmonic content of the distortion.
Please Note: When Oversampling is engaged, the Double button becomes accessible. This button is hidden when oversampling is off.
Multiband Frequency Control
The Multiband Frequency Control is a 3-way variable crossover control that can be used to tailor the sound of ClipShifter. The saturation/clipping processing can be selectively applied to any of the frequency bands. The controls include frequency selectors, gain controls, solo buttons, and a frequency selector control. The settings can be accessed by clicking the button next to the Input Gain control. Clicking the button a second time closes the control, although the current configurations are still applied to the audio.
Frequency Controls: The top two knobs control the frequency points of the 3-way crossover. The crossover utilizes a LR 4th order filter to split the audio into Low, Mid, and High sections. The default settings for the controls are 20 Hz for the Low control, and 20,000 Hz for the High control. When the controls are set to their default settings, the filters are disabled. As the knobs are changed from their default settings, the frequencies splits are engaged. When the filters are disabled, the corresponding Gain and Solo buttons are hidden. For a 2-band processor, either the Low frequency or High frequency can be disabled. The result is that the audio is split into 2 distinct frequency bands (with the Mid either functioning and the High band when High is disabled, or functioning as the Low band with the Low is disabled).
Gain Controls: The gain controls change the gain setting of each of the Low, Mid, and High sections prior to processing through the clipping processor. In effect, these controls are input gains for each frequency section.
Solo Buttons: Clicking a solo button will mute the audio from the other frequency bands. This can be useful in adjusting the appropriate frequency split and/or volume. The waveform display will also change to show the soloed output only.
Frequency Selector: The Frequency Selector determines what audio is processed through the clipping algorithm, and what audio is passed through to the output without any clipping or saturation. The default setting of for all of the audio signal to be processed through the saturation algorithm. When all three frequency bands are enabled, the selector can be set to process Low, Low + Mid, Mid, Mid + High, High, or All frequency bands. Clicking the Active button cycles through all of the available options. This is dependent on the number of frequency bands currently enabled. When a frequency is not enabled, the audio is still passed through to the output with all of the input, output, and band-specific gain; however, the clipping algorithm will be bypassed for this frequency band.
Please note: the input gain displayed within the waveform history view and input VU meters show the audio that is being processed by the clipping algorithm, even if no clipping is currently occurring. When the Frequency Selector is set to process one or two bands, the displayed input values will show the level of the Frequency Selector bands. This includes any input gain and frequency specific gain.
Mid Side Processing
Located between the Initial and End Threshold knobs are the Mid Side Processing controls. The controls are similar to the Multiband Frequency controls. They enable ClipShifter to process either the Mid or Side component of the audio through the clipping algorithm. By default, ClipShifter processes the audio as Left and Right signals.
Select Button: The Select button toggles settings between Left/Right, Mid, and Side. This button controls which signal is sent to the clipping algorithm. For example, if Mid is selected, the Mid signal is clipped while the Side component of the audio is passed through to the output. Input gain, Output gain, and any Frequency gain are still applied to the non-selected audio components.
Please note: When the Select button is either Mid or Side, the input meters change to display Mid and Side input instead of Left and Right. The M indicates that the meter is displaying the Mid component of the audio. The S is for Side. In most circumstances, it is usual for the Mid signal to be considerably louder that the Side audio.
Gain: The Gain knob is used when the Select button is set to Mid or Side as an input gain control. This can be useful when the signal needs to be increased in order to get the desired clipping amount. The default setting is -6 dB.
The Gain knob functions like a sidechain control in that any gain that is applied prior to the clipping algorithm is subtracted after the signal is processed. The result is that the gain can be increase to get the desired clipping amount without drastically altering the stereo width/balance at the output. In particular, processing the Side band may need substantial gain in order to produce clipping.
Solo: When the Solo button is enabled, only the selected stereo/width signal is heard at the output. The other signal (i.e. Mid or Side) is muted.
Width: The Width knob is a final output control to balance the stereo width of the audio. The default setting of 0.0 does not boost or cut the Mid or Side signal. Decreasing the value will decrease the amount of Side audio in the output. The minimum value of -1.0 will make the output signal all Mid (i.e., Mono). Increasing the value will decrease the amount of Mid in the output. Setting the maximum value of +1.0 will completely remove all Mid components at the output.
Please Note: Drastic amounts of clipping and/or drastic Width settings can negatively impact the stereo output of ClipShifter. It may be useful to use a Stereo Scope plugin after ClipShifter to ensure that the stereo signal is not too wide. Extremely wide signals may have significant phase issues and incompatibility when played on mono devices.