ClipShifter: Paid Features

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.

 

Oversampling

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.,  -1dB above 17kHz).

 

Double Processing

2013-09-16 14_55_58-ClipShifter (x86 bridged)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.

 

Multiband (EQ) Frequency Control

EQ Controls

The EQ controls feature 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, process selector buttons, gain controls, solo buttons, and a gain select button.

 

 

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 controls 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).

Process Buttons:  When the Frequency controls are engaged, the Process buttons are accessible.  These buttons control how the frequency bands are processed through the clipping algorithm.  When all the buttons are disengaged, the entire signal is processed through the clipping algorithm (including any frequency gains).  Conversely, when all of the three buttons are enabled, each frequency is processed individually through the clipping algorithm.  Although the same controls are used to determine the clipping threshold (i.e., Initial and End threshold, Attack, Release, etc.), each frequency band is processed independent of the other bands.

When some frequency bands are enabled and other bands are disabled, only the frequency bands that are enabled will be processed through the clipping algorithm.  The disabled bands will pass through the plugin with all the appropriate gains (i.e., In gain, Out gain, any EQ gain).  The disabled bands will also not affect ClipShifter’s calculation for shifting the internal clipping threshold.

Gain Controls:  The gain controls change the gain setting of each of the Low, Mid, and High sections.  They are closely related to the Gain Select button.  By using the Gail Select button, the EQ gains can be moved to different points within the processing chain.

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 input and output only.

Gain Select:  The Gain Select button controls how the EQ gains are applied to the signal.  This has the effect of controlling when the gain occurs within the processing chain.  The Gain Select control has three different options: In Gain, Out Gain, and SideChain.

When In Gain is selected, and frequency gains are applied immediately before the signal is routed through the clipping algorithm.  The result is that the frequency gain control can be used to determine how much clipping is applied.  When Out Gain is selected, the gain is applied to the signal immediately after the clipping algorithm.  Gain that is applied to the output will not impact the amount of clipping, it will only effect to EQ of the output signal.  When either In Gain or Out Gain is selected, the frequency gains can be used to tailor the sound.  This is regardless of whether or not the frequency Process button is engaged or not.

When SideChain is selected, the gain is applied to both the input and output; however, the result is a 0 dB gain for that EQ band.  First, any gain is applied to the frequency band before the signal is routed through the clipping algorithm.  When the signal exits the clipping algorithm, the same amount of gain is subtracted from the output.  This results in a 0 dB gain.  Although ClipShifter does not have a true SideChain processing path (like some compressors or noise gates), the SideChain option mimics this effect.

If a gain of +3 dB is selected for the low frequency, the following occurs:  First, the +3 dB is applied to the low frequency.  Then the signal is processed through the clipping algorithm.  Finally, -3 dB of gain is applied to the output signal.  Regardless of the setting on the gain control (i.e., either positive or negative gain), the gain is applied before clipping, and the inverse gain is applied after clipping.

 

 

Mid Side Processing

Mid/Side Controls

The Mid Side Controls are similar to the EQ 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 independent Left and Right signals.

 

 

M/S Mode button:  The M/S Mode button toggles settings between Left/Right stereo processing, and Mid/Side processing.  When the button is disengaged, the controls are hidden since they are not applicable.

Process button:  The Process buttons determine if the Mid and/or Side bands are passed through the clipping algorithm.  Engaging the button enables clipping.

Gain:  The Gain knob is used when the Process button is engaged.  The gain is applied prior to the clipping algorithm.  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.

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