Methods and devices for coding or decoding an audio signal or bit stream

US6975254B1 · kind B1 · utility

Assignee

• Fraunhofer-Gesellschaft zur förderung der angewandten Forschung e.V. · DE

Inventors

• Ralph Sperschneider · Erlangen, DE
• Martin Dietz · Nuremberg, DE
• Andreas Ehret · Wendelstein, DE
• Karlheinz Brandenburg · Erlangen, DE
• Heinz Gerhaeuser · Erlangen, DE
• Ali Nowbakht-Irani · Erlangen, DE
• Pierre Lauber · Nuremberg, DE
• Roland Bitto · Nuremberg, DE

Key dates

• Filing date: Dec 28, 1998
• Grant date: Dec 13, 2005
• Expiry date: Dec 28, 2018

Classification

• Technology area (CPC H): Electricity
• CPC primary: H04B1/662
• WIPO field: Basic communication processes
• WIPO sector: Electrical engineering

Abstract

In a method for coding an audio signal to obtain a coded bit stream, discrete-time samples of the audio signal are transformed into the frequency domain to obtain spectral values. The spectral values are coded with a code table having a limited number of code words of different lengths to obtain spectral values coded by code words, the length of a code word assigned to a spectral value being that much shorter the higher the probability of occurrence of the spectral value is. A raster is then specified for the coded bit stream, the raster having equidistant raster points and the distance between the raster points depending on the code table(s) used. In order to obtain error-tolerant Huffman coding, priority code words, which represent particular spectral values which are psychoacoustically more important than other spectral values, are so arranged in the raster that the start of each priority code word coincides with a raster point.