Low-bitrate Audio Enhancement Metadata Control
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Solution Overview
Problem
Low-bitrate audio coding introduces artifacts such as pre-echo noise and quantization noise, degrading audio quality, and existing methods either increase computational load at the decoder or lack control over enhancement processes, potentially altering the artistic intent of the content creator.
Innovation Solution
A method and system for generating enhancement metadata to control audio enhancement at the decoder side, allowing content creators to choose the type and amount of enhancement applied to low-bitrate coded audio data, using a Generative Adversarial Network (GAN) setting and user interaction to ensure artistic intent is preserved.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If low-bitrate audio coding is used to reduce bandwidth and storage requirements, then bandwidth and storage efficiency are improved, but audio quality deteriorates due to coding artifacts such as pre-echo noise and quantization noise
Solution Approach 1:
The patent converts the harmful quantization noise into a beneficial tool by using noise shaping techniques. The system deliberately introduces shaped quantization noise that is psychoacoustically masked by the audio signal itself, transforming what would be audible distortion into imperceptible noise. This allows low-bitrate coding to maintain perceived audio quality while reducing bandwidth and storage requirements.
Solution Approach 2:
The patent applies temporal noise shaping by modifying the spectral parameters of quantization noise in the time domain. By applying prediction filters that shape the noise spectrum according to the audio signal's temporal characteristics, the system changes the distribution of quantization noise to concentrate it in less perceptible frequency regions, thereby improving audio quality at low bitrates.
2Object-affected harmful factors
If temporal noise shaping is applied to reduce pre-echo noise, then audio quality is improved, but computational complexity increases
Solution Approach 1:
The patent implements a self-service mechanism where the audio signal itself provides the masking information needed for noise shaping. The system uses the audio signal's spectral and temporal characteristics to automatically determine where quantization noise should be shaped, eliminating the need for separate complex analysis algorithms. This reduces computational complexity while maintaining effective pre-echo noise reduction.
3Object-affected harmful factors
If decoder-side enhancement is applied to improve audio quality, then audio fidelity is improved, but control over artistic intent is lost
Solution Approach 1:
The patent applies enhancement algorithms during the encoding phase rather than decoding phase. By performing noise shaping and other enhancement operations before compression, the system embeds the enhancement parameters directly into the bitstream. This preliminary action ensures that the content creator's artistic intent is preserved while still achieving audio quality improvement, as the enhancement is applied in a controlled manner during encoding rather than as an automatic post-processing step.
Data Source
AI summary
Described herein is a method of low-bitrate coding of audio data and generating enhancement metadata for controlling audio enhancement of the low-bitrate coded audio data at a decoder side, including the steps of: (a) core encoding original audio data at a low bitrate to obtain encoded audio data; (b) generating enhancement metadata to be used for controlling a type and/or amount of audio enhancement at the decoder side after core decoding the encoded audio data; and (c) outputting the encoded audio data and the enhancement metadata. Described is further an encoder configured to perform said method. Described is moreover a method for generating enhanced audio data from low-bitrate coded audio data based on enhancement metadata and a decoder configured to perform said method.