developed by David E. Blackmer, founder of Dbx, Inc. It used a root-mean-squared (RMS) encode/decode algorithm with the noise-prone high frequencies boosted, and the entire signal fed through a 2:1 compander. dbx operated across the entire audible bandwidth and, unlike Dolby B, was unusable without a decoder. However, it could achieve up to 30 dB of noise reduction.

Since analog video recordings use frequency