Multi-mode audio codec and CELP coding adapted therefore

US8744843B2 · kind B2 · utility

Assignee

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

Inventors

• Ralf Geiger · Erlangen, DE
• Guillaume Fuchs · Erlangen, DE
• Markus Multrus · Nuremberg, DE
• Bernhard Grill · Lautenbächle, DE

Key dates

• Filing date: Apr 18, 2012
• Grant date: Jun 3, 2014
• Expiry date: Apr 18, 2032

Classification

• Technology area (CPC G): Physics
• CPC primary: G10L2019/0002
• WIPO field: Computer technology
• WIPO sector: Electrical engineering

Abstract

In an embodiment, bitstream elements of sub-frames are encoded differentially to a global gain value so that a change of the global gain value results in an adjustment of an output level of the decoded representation of the audio content. Concurrently, the differential coding saves bits. Even further, the differential coding enables the lowering of the burden of globally adjusting the gain of an encoded bitstream. In another embodiment, a global gain control across CELP coded frames and transform coded frames is achieved by co-controlling the gain of the codebook excitation of the CELP codec, along with a level of the transform or inverse transform of the transform coded frames. In another embodiment, the gain value determination in CELP coding is performed in the weighted domain of the excitation signal.