Scalable Audio Decoder Postfilter for Low-Latency Noise Reduction
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Solution Overview
Problem
Existing audio codecs face challenges in reducing coding noise during speech encoding, particularly in conversational applications where pitch postfilters require access to future speech signal samples, leading to increased algorithmic delay and affecting communication quality.
Innovation Solution
A scalable decoder device and method that combines primary and secondary decoded signals using a combiner arrangement, allowing for weighted combination of postfiltered signals without adding additional delay, utilizing a primary decoder and secondary decoder to enhance audio quality without increasing algorithmic delay.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If pitch postfilters evaluate future speech signals by buffering the decoded audio signal, then the coding noise is reduced and audio quality is improved, but the algorithmic delay increases and inter-activity is affected
Solution Approach 1:
The patent segments the decoded signal into multiple layers (base layer and enhancement layers) with different delay characteristics. The base layer is processed with minimal delay for real-time interaction, while enhancement layers are buffered and processed to reduce coding noise. This segmentation allows simultaneous optimization of both audio quality and inter-activity by assigning different processing strategies to different signal components.
2Manufacturing precision
If additional layers are added to provide enhancement in scalable coding, then the audio quality is improved, but the device complexity increases
Solution Approach 1:
The patent implements nested decoding where enhancement layers are embedded within the base layer structure. The base layer decoder processes the core signal, and enhancement layer decoders are nested within this structure to add refinement. This nested architecture allows progressive quality improvement while maintaining a hierarchical complexity structure where each layer builds upon the previous one, enabling scalable complexity adaptation.
Solution Approach 2:
The patent employs dynamic layer activation where the decoder can adaptively enable or disable enhancement layers based on available computational resources and quality requirements. The combiner arrangement dynamically adjusts the weighting and combination of signals from different layers, allowing the system to optimize between quality and complexity in real-time based on operational conditions.
Data Source
AI summary
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).