Process of low sampling rate digital encoding of audio signals

USRE44897E1 · kind E1 · reissue

Assignee

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

Inventors

• Oliver Kunz · Seßlach, DE
• Martin Dietz · Nuremberg, DE
• Rainer Buchta · Herzogenaurach, DE
• Jurgen Zeller · Ismaning, DE
• Karlheinz Brandenburg · Erlangen, DE
• Martin Sieler · Achern, DE
• Heinz Gerhauser · Waischenfeld, DE

Key dates

• Filing date: May 17, 2013
• Grant date: May 13, 2014
• Expiry date: May 17, 2033

Classification

• Technology area (CPC —): General

Abstract

In a method for coding an audio signal digitized at a low sampling rate to obtain time domain audio samples. A frequency domain representation of the time domain audio samples is produced. The frequency domain representation includes successive frequency lines. These frequency lines are grouped into a plurality of scale factor bands. The successive frequency lines in a scale factor band are coded with the same scale factor. A plurality of regions is formed by grouping the scale factor bands, wherein successive scale factor bands form a region within which all the scale factors are coded with the same number of bits, which is determined according to the largest scale factor of the region. The scale factors assigned to scale factor bands within the highest region that includes the higher frequency successive frequency lines are set to zero. The frequency lines in the highest region are coded using the zero-valued scale factors that correspond to a multiplication factor of 1. The scale factors for the highest region, however, are not coded. Thus, the bits that would be required for coding these zero-valued scale factors are saved and can be used for a finer quantization of the rest of…