What is a bitcrusher effect?
Bitcrusher effects can offer a variety of capabilities, but all of them feature two main functions: sample rate reduction, and bit depth reduction.
Sample rate reduction reduces how much information an audio signal has over time. For example, if your project uses a common sample rate of 44.1 kHz, that’s 44,100 amplitude level values (or ‘samples’) for each second of audio.
This gives us a very clear sound, and the 44.1kHz value is commonly used because it’s just over twice the limit of human hearing (around 20kHz), and a sample rate of twice the maximum frequency present in a signal is necessary to capture that signal accurately. This is known as the Nyquist frequency.
Reducing the sample rate introduces what are known as aliasing errors, which distort the higher frequencies present in the signal. While this distortion is usually undesirable, it can be useful for certain creative effects.
Bit depth reduction reduces the amount of data used to describe the amplitude level of a sample. A bit can be either a 0 or a 1. So, if you have a 24-bit audio signal, each sample can be one of 16,777,216 possible values, enough fidelity to be very convincing to the human ear.
However, if you were to reduce the bit depth to, say, 4-bit, that’s only 16 different possible values. This is nowhere near as convincing to the human ear, and gives us a much noisier signal. You can read more about the relationship between bit depth and noise.
So, we can think of sample rate reduction as reducing the ‘resolution’ of an audio signal over time, and bit depth reduction as reducing the ‘resolution’ of an audio signal’s amplitude. These effects give us different-sounding results, and can be used independently or together to achieve creative effects.