Method for signalling a noise substitution during audio signal coding

US6766293B1 · kind B1 · utility

Assignee

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

Inventors

• Jürgen Herre · Buckenhof, DE
• Uwe Gbur · Berlin, DE
• Andreas Ehret · Wendelstein, DE
• Martin Dietz · Nuremberg, DE
• Bodo Teichmann · Ergolding, DE
• Oliver Kunz · Seßlach, DE
• Karlheinz Brandenburg · Erlangen, DE
• Heinz Gerhauser · Waischenfeld, DE

Key dates

• Filing date: Aug 18, 1999
• Grant date: Jul 20, 2004
• Expiry date: Aug 18, 2019

Classification

• Technology area (CPC H): Electricity
• CPC primary: H04B1/665
• WIPO field: Telecommunications
• WIPO sector: Electrical engineering

Abstract

In a method for signalling a noise substitution when coding an audio signal, the time-domain audio signal is first transformed into the frequency domain to obtain spectral values. The spectral values are subsequently grouped together to form groups of spectral values. On the basis of a detection establishing whether a group of spectral values is a noisy group or not, a codebook is allocated to a non-noisy or tonal group by means of a codebook number for redundancy coding of the same. If a group is noisy, an additional codebook number which does not refer to a codebook is allocated to it in order to signal that this group is noisy and therefore does not have to be redundancy coded. By signalling noise substitution by means of a Huffman codebook number for noisy groups of spectral values, which are e.g. sections made up of scale factor bands which do not have to be redundancy coded, an opportunity is provided to indicate the presence of a noise substitution in a scale factor band in the bit stream syntax of the MPEG-2 Advanced Audio Coding (AAC) Standard without having to interfere with the basic coding structure and without having to meddle with the structure of the existing bit str…