Two-Channel Audio Decoding with Intelligent Gap Filling
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Solution Overview
Problem
Current audio codecs face limitations in bandwidth extension techniques, which restrict high-frequency content reconstruction, leading to loss of detail and timbre, and require transformation into new domains, causing computational complexity and memory issues, especially in mobile devices.
Innovation Solution
The proposed solution involves an Intelligent Gap Filling (IGF) method that regenerates high-frequency spectral portions using parametric data and two-channel identifications, allowing for efficient encoding and decoding within the same spectral domain without downsampling or upsampling, and fills spectral gaps using frequency tiles from tonal portions, preserving the audio signal's spectral envelope.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If bandwidth extension techniques are used to reconstruct high-frequency content, then audio quality is improved, but transformation into new domains is required causing computational complexity and memory issues
Solution Approach 1:
The patent copies spectral information from low-frequency regions to high-frequency regions by identifying source spectral portions and copying them to target spectral portions. This avoids complex transformations while reconstructing high-frequency content, thereby improving audio quality without increasing computational complexity
Solution Approach 2:
The patent replaces traditional mechanical domain transformations (filter banks, transposition) with direct spectral domain operations. By working entirely in the spectral domain using MDCT coefficients, the system eliminates the need for complex time-frequency transformations, reducing computational complexity and memory requirements
2Manufacturing precision
If bandwidth extension techniques are used to reconstruct high-frequency content, then audio quality is improved, but transformation into new domains is required causing memory issues
Solution Approach 1:
The patent copies spectral information directly within the same memory space by identifying source and target spectral portions and performing in-place copying operations. This eliminates the need for separate memory buffers required by traditional transformation methods, reducing memory usage while maintaining audio quality
Solution Approach 2:
The patent replaces transformation-based methods that require additional memory buffers with direct spectral domain copying operations. By working entirely in the spectral domain, the system avoids allocating memory for transformed domains, thereby reducing overall memory requirements
3Loss of information
If spectral gaps are filled using traditional bandwidth extension, then high-frequency content is reconstructed, but detail and timbre are lost
Solution Approach 1:
The patent applies local quality by analyzing individual spectral portions and determining their tonal characteristics. For tonal spectral portions, the system copies the actual spectral details rather than generating artificial content, thereby preserving local timbre and detail while reconstructing high-frequency content
Solution Approach 2:
The patent changes the approach from parameter-driven synthesis to spectral copying. By using the actual spectral coefficients from source portions as the target portions, the system preserves the original signal's timbre and detail characteristics rather than losing them through parametric approximation
4Manufacturing precision
If full-bandwidth encoding is implemented, then audio quality is improved, but bitrate consumption increases
Solution Approach 1:
The patent extracts and transmits only the essential low-frequency spectral information, allowing the high-frequency content to be reconstructed through copying operations at the decoder. This extracts the minimum necessary information for high-quality reconstruction, thereby improving audio quality while reducing bitrate consumption
Solution Approach 2:
The patent changes the encoding strategy from transmitting all frequency bands to transmitting only low-frequency bands with implicit high-frequency reconstruction. By changing from full-bandwidth transmission to selective bandwidth transmission with spectral copying, the system achieves full-bandwidth quality at reduced bitrate
Data Source
AI summary
An apparatus for generating a decoded two-channel signal includes: an audio processor for decoding an encoded two-channel signal to obtain a first set of first spectral portions; a parametric decoder for providing parametric data for a second set of second spectral portions and a two-channel identification identifying either a first or a second different two-channel representation for the second spectral portions; and a frequency regenerator for regenerating a second spectral portion depending on a first spectral portion of the first set of first spectral portions, the parametric data for the second portion and the two-channel identification for the second portion.