Audio Subband Gain Prediction When Quantization Bands Shift
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Solution Overview
Problem
Existing speech/audio signal encoding technologies face challenges when the quantization target band changes between frames, leading to increased encoding errors and degraded audio quality, especially when frequency components of different bands are targeted in each frame.
Innovation Solution
An encoding apparatus and method that transform input signals into the frequency domain, select a quantization target band, quantify the shape of frequency domain parameters, and encode gain information, while a decoding apparatus and method receive and decode this information to generate a time-domain signal, employing predictive encoding based on the number of common subbands between frames.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If predictive encoding is performed based on time domain parameters, then compression efficiency is improved, but encoding error and decoded signal audio quality degradation increase when quantization target band changes between frames
Solution Approach 1:
The patent changes the parameter basis from time domain to frequency domain for predictive encoding. Specifically, it uses frequency domain parameters (spectral shape and gain in quantization target bands) instead of time domain parameters for predictive encoding, which resolves the quality degradation issue when quantization bands change between frames while maintaining compression efficiency
Solution Approach 2:
The patent segments the frequency domain into multiple subbands and selectively applies predictive encoding only to the quantization target band. By dividing the frequency domain and applying prediction only where needed (in the quantization target band), it maintains compression efficiency while avoiding errors in non-quantization bands
2Adaptability or versatility
If frequency domain parameter encoding is applied to different quantization target bands, then adaptability is improved, but encoding complexity increases
Solution Approach 1:
The patent applies different processing to different frequency bands by performing predictive encoding only in the quantization target band while using direct encoding for other bands. This local differentiation allows adaptability to changing quantization targets while avoiding unnecessary complexity in bands where predictive encoding is not applicable
Solution Approach 2:
The patent dynamically adjusts the encoding approach based on the quantization target band selection. The predictive encoding is applied conditionally - only when the band is identified as a quantization target - allowing the system to adapt to different encoding scenarios without requiring complex processing in all cases
Data Source
AI summary
An encoding device includes: a frequency region converter which converts an inputted audio signal into a frequency region; a band selector which selects a quantization object band from a plurality of sub bands obtained by dividing the frequency region; and a shape quantizer which quantizes the shape of the frequency region parameter of the quantization object band. When a prediction encoding presence/absence determiner determines that the number of common sub bands between the quantization object band and the quantization object band selected in the past is not smaller than a predetermined value, a gain quantizer performs prediction encoding on the gain of the frequency region parameter of the quantization object band. When the number of common sub bands is smaller than the predetermined value, the gain quantizer non-predictively encodes the gain of the frequency region parameter of the quantization object band.