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Technique for encoding/decoding of codebook indices for quantized MDCT spectrum in scalable speech and audio codecs

An index and codebook technology, applied in the field of encoders and decoders, can solve very complex problems

Inactive Publication Date: 2010-09-29
QUALCOMM INC
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This is practically impossible for two reasons: it would be very complex to implement and the "best vocalization" selection criterion implies that the human listener

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  • Technique for encoding/decoding of codebook indices for quantized MDCT spectrum in scalable speech and audio codecs
  • Technique for encoding/decoding of codebook indices for quantized MDCT spectrum in scalable speech and audio codecs
  • Technique for encoding/decoding of codebook indices for quantized MDCT spectrum in scalable speech and audio codecs

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[0049] Figure 4 is a block diagram of a scalable encoder 402 according to one example. In a pre-processing stage prior to encoding, the input signal 404 is high-pass filtered 406 to suppress unwanted low-frequency components to produce a filtered input signal S HP (n). For example, high pass filter 406 may have a 25 Hz cutoff for wideband input signals and 100 Hz for narrowband input signals. The filtered input signal S is then resampled by the resampling module 408 HP (n) Resampling is performed to produce a resampled input signal S 12.8 (n). For example, the original input signal 404 may be sampled at 16 kHz and resampled to 12.8 kHz, which may be an internal frequency for layer L1 and / or L2 encoding. The pre-emphasis module 410 then applies a first-order high-pass filter to emphasize the resampled input signal S 12.8 (n) higher frequencies (and attenuate lower frequencies). The resulting signal is then passed to an encoder / decoder module 412, which may perform layer...

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Abstract

Codebook indices for a scalable speech and audio codec may be efficiently encoded based on anticipated probability distributions for such codebook indices. A residual signal from a Code Excited Linear Prediction (CELP)-based encoding layer may be obtained, where the residual signal is a difference between an original audio signal and a reconstructed version of the original audio signal. The residual signal may be transformed at a Discrete Cosine Transform (DCT)-type transform layer to obtain a corresponding transform spectrum. The transform spectrum is divided into a plurality of spectral bands, where each spectral band having a plurality of spectral lines. A plurality of different codebooks are then selected for encoding the spectral bands, where each codebook is associated with a codebook index. A plurality of codebook indices associated with the selected codebooks are then encoded together to obtain a descriptor code that more compactly represents the codebook indices.

Description

[0001] Claim of priority under 35 U.S.C. §119 [0002] This patent application claims the title of "Low-Complexity Technique for Encoding / Decoding of Quantized MDCT Spectrum Encoding / Decoding in Scalable Speech+Audio Codec" filed on November 4, 2007 MDCT Spectrum in Scalable Speech+Audio Codecs), which is assigned to the present assignee and is hereby expressly incorporated herein by reference. technical field [0003] The following description relates generally to encoders and decoders, and in particular to efficient ways of coding Modified Discrete Cosine Transform (MDCT) spectra as part of scalable speech and audio codecs. Background technique [0004] One goal of audio coding is to compress an audio signal to a desired limited amount of information, while maintaining as much as possible of the original sound quality. During encoding, an audio signal in the time domain is transformed into the frequency domain. [0005] Perceptual audio coding techniques such as MPEG La...

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G10L19/14
CPCG10L19/24
Inventor 尤里娅·列兹尼克
Owner QUALCOMM INC
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