Two-Channel Audio Decoding With Intelligent Spectral Gap Filling
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Solution Overview
Problem
Current audio codecs face limitations in coding efficiency and audio quality at low bitrates due to restricted bandwidth extension techniques that fail to accurately align tonal harmonics and introduce computational complexity, synchronization issues, and artifacts from transforming signals into new domains.
Innovation Solution
The implementation of Intelligent Gap Filling (IGF) technology, which regenerates spectral portions using parametric data and two-channel identification to adaptively fill spectral gaps, allowing for efficient coding in the same spectral domain without downsampling or upsampling, and employing Temporal Noise Shaping (TNS) or Temporal Tile Shaping (TTS) to reduce pre- and post-echoes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If bandwidth extension techniques are used to reduce coding bitrate, then coding efficiency is improved, but synchronization issues and artifacts are introduced
Solution Approach 1:
The patent applies preliminary action by performing gap filling in the spectral domain before inverse transformation to time domain. The spectral gaps are identified and filled with synthesized spectral components prior to the inverse transform, ensuring that the frequency domain representation is complete before conversion, thereby preventing synchronization issues and artifacts that would arise from incomplete spectral information.
Solution Approach 2:
The patent introduces the spectral domain as an intermediary representation between the time domain signal and the final decoded output. By transforming the signal to the spectral domain, performing gap filling operations, and then transforming back, the system mediates the bandwidth extension process to maintain synchronization accuracy while improving coding efficiency.
2Manufacturing precision
If spectral patching is used to fill high frequency regions, then audio quality is improved, but computational complexity increases
Solution Approach 1:
The patent applies copying by replicating existing spectral components from lower frequency regions to fill the spectral gaps in higher frequency regions. Instead of performing complex spectral analysis and synthesis, the system copies spectral patterns and applies parametric adjustments to reconstruct the high frequency content, thereby maintaining audio quality while reducing computational complexity.
Solution Approach 2:
The patent uses parameter changes by applying parametric adjustments to the copied spectral components. Rather than performing full spectral synthesis, the system modifies parameters such as spectral envelope, tilt, and temporal continuity of the copied components to match the target high frequency region, achieving high audio quality with reduced computational effort.
3Adaptability or versatility
If signal transformation to new domains is performed for bandwidth extension, then extended audio bandwidth is achieved, but synchronization issues and artifacts are introduced
Solution Approach 1:
The patent applies universality by performing the bandwidth extension process entirely within the spectral domain, which serves multiple functions: it enables gap filling, maintains synchronization, and avoids artifacts simultaneously. By making the spectral domain the universal working space for all bandwidth extension operations, the system achieves extended audio bandwidth without the synchronization issues and artifacts that arise from multiple domain transformations.
4Productivity
If downsampling and upsampling are used in bandwidth extension, then coding efficiency is improved, but computational complexity and synchronization issues increase
Solution Approach 1:
The patent applies taking out by extracting and removing the downsampling and upsampling steps from the bandwidth extension process. By working directly with the full-rate spectral representation and performing gap filling in the spectral domain, the system eliminates the need for rate conversion operations, thereby reducing computational complexity and synchronization issues while maintaining coding efficiency.
Data Source
AI summary
An apparatus for generating a decoded two-channel signal, comprising: a parametric decoder for providing parametric data for a second set of second spectral portions and a two-channel identification identifying for a second spectral portion of the second set of second spectral portions either a first two-channel representation for the second spectral portion of the second set of second spectral portions or a second two-channel representation for the second spectral portion of the second set of second spectral portions, the second two-channel representation being different from the first two-channel representation; and a frequency regenerator for regenerating the second spectral portion of the second set of second spectral portions depending on a first spectral portion of a first set of first spectral portions, the parametric data for the second spectral portion of the second set of second spectral portions and the two-channel identification for the second spectral portion of the second set of second spectral portions to acquire a regenerated second spectral portion of the second set of second spectral portions.