Dither

Introduction to Dither

Dither is a common process applied when changing the bit depth of an audio file.

Whenever you reduce the resolution (bit depth) of an audio signal you will introduce truncation errors, which can be a very unpleasant artifact if audible. The quantization noise is correlated to the audio signal which we perceive as more disturbing than uncorrelated noise. Dither introduces low level random noise to de-correlate the noise. Additionally, it is possible to alter the frequency distribution of the noise signal. The human ear has a frequency dependent sensitivity and it makes sense to "move" the noise to frequency regions where the ear is less sensitive. This process is called noise shaping and the Dither plug-ins offers detailed control over the noise shaping process.

User Interface

Parameter Settings

• Target resolution

Here you have to set the target resolution. If you want to change the resolution from 24 bit to 16 bit for example, you need to select 16.

• Enable noise shaping

Click to enable or disable the noise shaping filter

• Dither level (%)

Dither amplitude in percent of 1 LSB (least significant bit). This should be at 100% for complete de-correlation of quantization noise.

• Filter length (ms)

This allows you to set the length of the noise shaping filter in milliseconds. Longer filters allow more accurate shaping, but comes at CPU cost.

• Max. noise shaping (dB)

This sets he maximum gain allowed in the noise shaping filter. The higher the setting, the less audible the added noise will be, by moving the noise up in the frequency spectrum. However, too much energy concentration in the high frequency bands should be avoided as this can cause issues with certain digital to analog convertors.