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Postfilter for layered codecs

A post-filter and post-filtering technology, which is applied in the field of coding noise, can solve problems such as increasing codec algorithm delay and affecting communication quality, and achieve the effect of improving the quality of reconstructed signals

Active Publication Date: 2010-01-06
TELEFON AB LM ERICSSON (PUBL)
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0006] A problem with pitch postfilters that estimate future speech signals is that they require access to a future pitch period of the decoded audio or speech signal
However, in traditional applications of audio or speech codecs, this approach is undesirable since it would increase the algorithmic delay of the codec and thus affect the communication quality and especially the interactivity

Method used

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  • Postfilter for layered codecs
  • Postfilter for layered codecs
  • Postfilter for layered codecs

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Embodiment Construction

[0026] Throughout this disclosure, the same reference numerals will be used to designate equivalent or directly corresponding features in different figures and embodiments.

[0027] In order to fully understand the detailed description, certain terms must be more clearly defined to avoid confusion. In this disclosure, the term "parameter" is used as a generic term to represent any kind of signal representation, including bits or bit streams.

[0028] Different means and signals related to the secondary decoder are also defined below. "Secondary decoder" is a generic representation of different types of secondary decision making devices. It includes eg a secondary enhancement decoder or a secondary reconstruction decoder. A "Secondary Enhancement Decoder" relates to scalable coding and is thus a subset of the Secondary Decoder. Such a "secondary enhancement decoder" provides some kind of enhancement signal to be added to eg the primary decoded signal. "Secondary reconstruct...

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Abstract

A scalable decoder device (50) for signals representing audio comprises a primary decoder (21) connected to an input (40). The primary decoder (21) is arranged to provide a primary decoded signal (23) based on received parameters (4). A primary postfilter (31) is connected to the primary decoder (23) to provide a primary postfiltered signal (32). A secondary enhancement decoder (45) is connected to the input (40) and arranged to provide a secondary decoded enhancement signal (44). The device further comprises a combiner arrangement (55), arranged for combining the primary postfiltered signal (32) and a signal (53) based on the secondary decoded enhancement signal (44) into an output signal (6) to be provided at an output (6). The combining is made with an adaptable strength relation between contributions from the two signals. A method for decoding coded signals representing audio operates in analogy with the scalable decoder device (50).

Description

technical field [0001] The present invention relates generally to audio codecs, and in particular to reducing coding noise inserted into speech during coding. Background technique [0002] In general, audio coding, and speech coding in particular, performs a mapping from an analog input audio or speech signal to a digital representation in the coding domain and back to an analog output audio or speech signal. Digital representation is accompanied by quantization or discretization of values ​​or parameters representing audio or speech. Quantization or discretization can be seen as perturbing the true value or parameter with coding noise. Audio or speech coding techniques pertain to: performing coding such that the effect of coding noise in the decoded speech is as small as possible at a given bit rate. However, a given bit rate at which speech is encoded defines a theoretical lower limit to which the encoding noise can be reduced in the best case. The goal is to at least m...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G10L19/14G10L19/04
CPCG10L19/26
Inventor S·布鲁恩
Owner TELEFON AB LM ERICSSON (PUBL)