Reducing quantizer distortion with subtractive dithering

• Main Author: KOEN VOS
• Format: Patent
• Language: English
• Published: 07.07.2010
• Subjects: ACOUSTICS; MUSICAL INSTRUMENTS; PHYSICS; SPEECH ANALYSIS OR SYNTHESIS; SPEECH OR AUDIO CODING OR DECODING; SPEECH OR VOICE PROCESSING; SPEECH RECOGNITION

A method, system and program for encoding and/or decoding a speech signal. The method comprises: generating a first signal representing a property of an input speech signal; transforming the first signal using a simulated random-noise signal, thus producing a second signal; quantizing the second signal based on a plurality of discrete representation levels, thus generating quantization values for transmission in an encoded speech signal, and also generating a third signal being a quantized version of the second signal; and performing an inverse of the transformation on the third signal, thus generating a quantized output signal, wherein the generation of the first signal is based on feedback of the quantized output signal. The method further comprises controlling the transformation in dependence on a property of the first signal so as to vary the magnitude of a noise effect created by the transformation relative to the representation levels. The transforming can be subtraction of a pseudo-random noise signal which has variable energy.