What is a Bitcrusher?

 

Bitcrusher is a type of audio effect that has a low-quality distortion in its core. In addition, It produces a distortion by the reduction of the resolution or bandwidth of digital audio data. Furthermore, the sound it produces can be described as metallic or gritty. The sound impression changes when using bit crusher on audio ranges from subtle, more warmer, to extremely harsh sound depending on the amount of reduction.

 

Digital Audio

 

Digital audio consists of a rapid series of numeric samples that encode the changing volume of an audio waveform. To accurately represent a smooth waveform, digital audio requires a large number of samples at a high sample rate. The higher the rate, the more accurate the waveform. Higher sample rates are also allowing the accurate recording of higher frequencies. For example, DAWs today typically use 44.1 kHz or higher sample rates. Early digital gear used much lower sample rates to conserve memory for stored audio. A Speak & Spell from the 1970s, for instance, used a 10 kHz sample rate.Sample rate reduction (also called downsampling) intentionally reduces the sample rate to degrade the quality of the audio. With the reduction of sample rate waveforms become more coarse. This results in losing the high frequencies.  At extreme reductions, the waveform becomes metallic and very harsh sounding.

 

Sample Rate Reduction

 

Samples in digital audio are recorded as integers or floating-point (real) numbers stored in computer memory. Consequently, a series of on and off memory bits are encoding these numbers. The larger the number of bits, the more accurate a sample encodes the instantaneous volume level of a sampled audio waveform. DAWs today typically use 32-bit floating-point numbers. Early digital audio gear and video games used 8-bit integer samples or less. Roland’s classic TR-909 drum machine used 6-bit integer samples. Resolution reduction intentionally reduces the number of bits used for audio samples. However, as the bit depth goes down, waveforms become more stair-stepped. This results in losing the subtle volume variations. At extreme bit reduction, waveforms are becoming clicks. The waveform jumps abruptly from low to high and back again without intervening values.

 

Bit Depth

 

The Bitcrusher effect usually has at least two controls. One reduces the sample rate, while the other reduces resolution. The knob parameter for resolution, usually represented as bits depth,  most commonly ranges from 32 bits to 1 bit.  The parameter for sample reduction, usually represented as downsampling, is shown in Hz for a new sample rate or a reduction factor. Moreover, sample rate reduction is sometimes represented as a number of consecutive samples. A Value of 20 reduces the sample rate to 1/20th of its original rate.

 

Additional Resources & Source Texts

https://en.wikipedia.org/wiki/Bitcrusher