Patent ID: 6064743
Filing Date: 2000-05-16
Classification: G06F,G10H,H03K

Abstract:
Volume control circuitry for eliminating zipper noise in a digital wavetable audio synthesizer, comprising:(a) shift circuitry configured to store a volume increment value, having a first maximum value, in a binary format, and configured to shift bits of said volume increment value right a number of bit positions in response to a shift signal, whereinsaid first maximum value represents a maximum value to which said volume increment value can be set,said volume increment value represents a change in a volume component,said wavetable audio synthesizer is configured to provide said volume component to wavetable data addressed by said wavetable audio synthesizer, andeach time said shift circuitry shifts said volume increment value of said volume component, irrespective of a time period between shifts, said volume increment value is shifted a constant number of positions; and(b) control circuitry configured to generate said shift signal in order to cause said shift circuitry to shift said bits of said volume increment value right said number of said bit positions, whereinsaid number is at least one and is selected such that said volume increment value is limited to a second maximum value, andsaid wavetable audio synthesizer does not generate zipper noise when said volume increment value is limited to said second maximum value.