Dither - Ozone 9 Help

Publish date: 2024-05-08

Table of Contents

Overview

Ozone includes a comprehensive set of dithering tools to help you prepare studio-quality audio for different delivery formats. The Dither panel includes iZotope’s MBIT+ dither algorithm along with a unique set of meters to offer a complete view of the conversion process.

Dither panel full

Working with Dither

You can open the Dither panel by clicking on the Dither button in the I/O panel area of the mothership plug-in, application, and Maximizer component plug-in. You can enable/disable Dither processing using the power button to the left of the Dither button.

Dither button in the I/O

Using Dither in a DAW

Controls

The Dither panel includes the following controls:

Dither Control Panel

Bit Depth

Sets the target bit depth for the exported file. Choices include: 24, 20, 16, 12, or 8.

8 & 12 bit: preview only in Ozone app

The 8 and 12 bit Dither options can only be previewed in the Ozone application. The Ozone app export dialog does not include 8 or 12 as export bit depth options.

Auto-Blanking

Mutes dither output (i.e. dither noise) automatically when silence is detected (i.e. 0 bits of audio) in the input signal for at least 0.7 seconds.

Dither Amount

Selects the target number of bits (amplitude) of Dither to add to the signal. The following options are available:

Harmonic Suppression

Enables modification of truncation rules. Truncation can result in harmonic quantization distortion that adds overtones to the signal and distorts the timbre. Enabling this option will modify truncation rules in order to move harmonic quantization distortion away from overtones of audible frequencies. This can help maintain better tonal quality in the resulting signal. Harmonic Suppression doesn’t create any random dithering noise floor.

Harmonic Suppression and Artifacts

Harmonic Suppression can only be enabled when Dither Amount is set to Off.

Limit Peaks

Suppresses peaks in the output signal that can be caused by more extreme dither settings. Dither noise is random in nature and has a very low amplitude, so peaks will not often be an issue. In cases where you need to apply more aggressive dithering, high frequency dither noise can be amplified significantly after noise shaping, resulting in spurious peaks in the dither signal (up to -60 dBFS for 16-bit quantization).

Noise Shaping

Determines the amount of noise shaping applied during the dithering process, ranging from Off (no noise shaping) to Max (roughly 14 dB of audible noise suppression). Noise shaping pushes the dither noise into less audible frequency ranges, allowing for greater dithering with less perceived noise.

Noise Shaping Curve

Displays the general frequency curve of the selected noise shaping profile.

Dither Noise shaping curve

Bit Meter

Displays information about the digital activity of your program material. The bit meter is not a level meter, it displays which bits are being used. If a bit is used (goes from 1 to 0 or vice versa), the box representing that bit will light up.

Bit Meter Columns

  • Real-time bit activity in the left and right channels.
  • Overall (“peak hold”) bit activity in the left and right channels.
  • Generally, you want to see activity in each of the bits that are relevant to the bit depth you are exporting to. A signal like DC offset will toggle a lower bit once (lighting the outside column), but would never toggle it after that since the bit is being held. If you’re dithering down, you only want to see 16, 12, or 8 bits lit (corresponding to the output bit depth of the dither).

    Why doesn't the top bit light up in the Bit Meter?

    When samples are stored as a binary number, negative samples are specially encoded. Since the binary representation of negative numbers is not intuitive, Ozone takes the absolute value of each sample before plotting it on the bit meter. Since the MSB (most significant bit) is only set when a sample is negative, this bit will never light up. We simply included the top bit as placeholder for completeness.

    Reset

    Clears the state of the Bit Meter. Clicking on the Bit Meter will also reset the peak hold information.

    DC Offset

    This section allows you to monitor and filter DC Offset from your track before limiting.

    Audio signals are normally represented by an alternating current (AC) signal with an average value of zero. DC offset can be caused by things like malfunctions in analog recording equipment or faulty A/D conversion. In an FFT (Fast Fourier Transform) analyzer, DC offset is represented with energy at zero frequency (0 Hz). DC offset can be effectively removed with a high-pass filter set to a very low frequency value.

    It is important to distinguish DC offset from waveform asymmetry. Asymmetry skews the waveform shape towards positive or negative levels, but the average current stays at zero. Many audio signals are naturally asymmetric in nature. Unlike DC offset, asymmetry has no particular energy near 0 Hz and can be reduced using phase rotation filters.

    DC Offset Meter

    Displays the amount of DC Offset present in the signal.

    DC Offset Meter

    Click on the DC Offset meter to clear and reset the calculation.

    Filter

    Enables a highpass filter with a cutoff frequency of 1 Hz to filter DC offset before limiting is applied.

    DC Offset Filter Module Dependency

    In the mothership plug-in or application, the DC offset meter and filter are only available if the Maximizer or Vintage Limiter module is in the signal chain. When the Filter is enabled, it is applied to the signal before it enters the Maximizer or Vintage Limiter module (whichever comes first, if both are present in the signal chain).

    Ozone 9.12.1

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