Dithering is used to tame the quantization distortion that happens when converting between bit depths due to requantization. Dither also preserves more of the dynamic range of a signal when converting to a lower bit depth. The result is a more pleasing sound and smoother fades. Controls New bit depth: This sets the target resolution bit depth of the audio file. Noise shaping: Sets the aggressiveness of dither noise shaping. It is possible to provide more effective and transparent dithering by shaping the dithered noise spectrum so less noise is in the audible range and more noise is in the inaudible range.
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Never Miss an Article! Sign up for our newsletter and get tutorials and tips delivered to your inbox. Can a topic possibly get any nerdier?
My guess is no. Newsflash, though: not only am I a giant nerd, I also love to try to make complex topics accessible through analogies and visual demonstrations. Dither is simply noise. I get it. Here it is: Apply dither any time you reduce bit depth.
What the heck is dither even doing? In a nutshell, the problem is one of amplitude resolution, or how accurately we can measure the level of a signal using ones and zeros. When we try to measure an infinitely variable analog source our audio using a finite number of digital values those ones and zeros , there are bound to be some errors.
Sometimes the analog level will be a little above the closest digital value, while other times it will be below. In digital audio, this rounding error is known as quantization distortion. However, as bit-depth is reduced, the level of this distortion creeps up. As you approach 16 bits, it can start to get rather noticeable and nasty sounding in reverb tails, fade-outs, and other quiet sections. Without going into too much detail, this is because the number of bits dictates how many discrete values you have to store levels at.
To go back to the measuring tape analogy, you could think of it like this: if 8 bits let you measure only in feet, 9 bits would give you 6 inch increments, 10 bits would give you 3 inch increments, etc. Every time you add a bit, you double how accurately you can measure.
Going the other way, this means that every time you lose a bit, you double the potential rounding error. First, here is a 1kHz sine wave at dBFS, represented at bit floating point. A little worse for wear, but still more or less recognizable. Finally, here it is reduced to 16 bits, again without dither.
Two things: First, only the very peaks of the sine wave were high enough in level to get rounded up to the smallest value a bit file can represent, while the rest were rounded down to zero. Second, depending on where the peak of the sine wave fell in relation to the sample timing, either one or two samples were rounded up. Dither to the rescue! OK, now will you tell me what the heck dither is even doing?
Yes, yes I will. At its heart, dither is simply noise, and noise, by virtue of its very nature, is random. Back in the early days of digital audio, some clever engineers realized they could use a random noise signal to their advantage. By mixing it with the signal being quantized, they could add enough variation that the original signal could be preserved. Not only does this help preserve the signal, it actually removes the distortion that is tied to its frequency content. What if we add dither before reducing to 16 bits?
Am I really saying that adding some very low level noise to the signal before reducing the bit-depth will mathe-magically fix this? You bet I am! This results in a signal-to-noise ratio increase of about 16 dB. The previously present distortion tones are gone. Not masked or buried below the noise, but actually removed! I really want you to let these facts sink in, especially that last one.
That said, a consistent, evenly distributed bit of very quiet noise is sonically preferable to harmonic distortion tied to both level and frequency. All this by introducing a little random variation into the mix. At bit depths of 8 or 16 bits, this can make an appreciable difference. Still, it will remove quantization distortion which, due to its tonal nature, has a much higher chance of being audible.
As such, a flat, TPDF-type dither is really fine. Different audio workstations operate in different ways, but most offer some method to commit a complex audio effects chain to a file. Conclusion Hopefully this helps you understand why dither is so crucial to digital audio, how and why it works, and when it should be applied.
It will always do more good than harm. If your interest has been piqued and you want to dive even further into the topic, we have a full guide available here.
Dither [STD & ADV]
Choose an appropriate dithering signal Aside from avoiding the pitfall of converting down too early, you can also improve your mix by choosing an appropriate dithering signal. Returning to the above example, you might end up with a final mix at bit or even bit depth. To use Ozone for dithering, you must first manually disable any internal dithering applied by the hostapp. This prevents the two dithering signals from adding together and conflicting. So convert your mix down to Finally, load this final
Using Resampling and Dither Modules (RX Advanced Only)
Never Miss an Article! Sign up for our newsletter and get tutorials and tips delivered to your inbox. Can a topic possibly get any nerdier? My guess is no. Newsflash, though: not only am I a giant nerd, I also love to try to make complex topics accessible through analogies and visual demonstrations. Dither is simply noise.