Dither
Adding a tiny amount of noise before bit-depth reduction so quantization error becomes noise
Related
Dither is very low-level noise added before reducing bit depth, so quantization error no longer correlates with the signal. Going from 24-bit to 16-bit discards the lowest bits; truncating directly leaves gritty distortion on quiet passages and reverb tails, while dither turns it into even hiss.
It cannot restore lost detail; it only makes the loss sound more natural, at the cost of a slightly higher noise floor. Mastering applies it once when delivering 16-bit CD audio or certain lossy encodes; repeating it in a 24-bit project makes no sense. Noise shaping pushes the noise toward less sensitive highs.
The usual mistake is to think dither adds resolution, or that several passes are safer. It belongs once, at the final bit-depth reduction; in a 24-bit or floating-point project it only adds noise.
Related → Bit Depth
Sources
- 抖动与噪声整形，参 Bob Katz, Mastering Audio 与通行母带教材；本文为原创表述
Used for fact-checking only; all prose is original.