When you are just starting out in audio production, you`re likely to be surrounded by dozens of confusing definitions — and dithering is one of them. Obviously, it`s worth understanding the issue in detail, because the dithering option is a very necessary tool in the mixing mastering online audio specialists arsenal. So, in the article, you will learn the main subtleties: what is it, the various types, when dithering is necessary, and when it`s inappropriate.
Dithering in Detail
Unlike analog sound recording, digital one is designed to fit music into a finite series of zeros and ones. No matter how large the quantization bit is and how high is its frequency (for example, 16/44.1 or studio 24/192 and higher), the recording accuracy is always finite. So, in the recording of any piece of music, there can be found stretched in time periods, too smooth frequency transitions, lingering vocals, and other moments.
This can cause a phenomenon of noise quantization. When the frequency fluctuations are too small to be captured on a digital recording at the selected frequency, the equipment “decides” to simplify such areas to a single value stretched over time. And dithering is a special method needed to eliminate too obvious manifestations of such an effect.
Thus, experts describe dithering as “the principle of reducing the nonlinear distortion of a signal during analog-to-digital conversion in a situation of a conversion capacity deficit”.
If you think that the audio dithering process is a new word in the music industry, then we hasten to surprise you. Interestingly, the method was invented during the Second World War. The pilots needed to calculate the projectile flying trajectory as accurately as possible — they applied special computers. Over time, engineers noticed:
- instruments worked better onboard an aircraft than on the ground;
- aircraft-induced vibration significantly reduced all military device errors.
So the specialists simply installed an additional motor in the device, which creates the necessary vibrations. The error-reducing vibration method was called a “dither” (from “didderen” — to shake). So, if vibrations are applied precisely in limited amounts, then they successfully convert a digitizing system to an analog one.
The Different Types of Dithering
Despite the complexity of the dithering music process, this tool is divided into several more types. At first sight, there`re no significant differences between them (at least, noticeable for the ordinary ear). Nevertheless, the method types are suitable for different purposes. For example, there are three main POW-r diversities depending on the track`s dynamic range:
- Type №1. The first variety is ideal for low dynamic range, but it should not be used when noise shaping.
- Type №2. Professionals apply it mainly for speech tracks (to improve the quality of vocal audios, podcasts, broadcasts).
- Type №3. The third method is capable of handling dynamic mixes on A+. This type can be used if the track contains orchestral, acoustic, or band music.
However, there are also additional types labeled “average” & “ultra” (they refer to the amount of squelch applied to a given signal). Also, dithering can be distinguished by the kind of the probability density function:
- RPDF with using a uniformly distributed rectangular probability density function;
- TPDF with using a triangular probability density function (it can be achieved by adding two independent RPDF sources);
- Gaussian PDF is characterized by a standard normal distribution.
Regardless of the method, dithering supplies areas with quantization noise with a portion of additional noise that animates them. This is the “fight fire with fire” effect. Sound recording regains the lost naturalness and beauty, even if the recording is already different from the original.
When to Use Dithering
However, you can’t just use the option whenever you want. Usually, dithering audio is recommended for downsampling a track. In other words, use dither whenever quantization artifacts appear in the audio.
Also, it`s required for music exporting & mastering. Upon the whole, such processes involve compressing a 32-bit floating or 24-bit audio file to 16-bit depth, so adding the dithering option is really necessary here. Additionally, it can be used successfully as the last effect in the signal chain.
When Not to Use Dithering
It`s known that dithering is a standard option for processing audio tracks, but you haven`t to apply it every time. The method can be ignored in some situations:
- using a mastering engineer for track preparation;
- exporting track in high resolution;
- converting audio to AAC or .mp3 formats.
To crown it all, dithering is a valuable technique to make the quantization error virtually independent of the original signal. You can use various tool options depending on the desired result and the audio track type. The method is ideal for downsampling audio as well as exporting and mastering tracks. However, it isn`t always required, and sometimes you can do well without it — for example, converting the track to certain formats or exporting it in high resolution.
We hope this information was useful and now you will enjoy using the Dither option, getting excellent results!