Audio Signal Reconstruction Bands Using IGF Energy Information
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Solution Overview
Problem
Current audio codecs face limitations in coding high-frequency content at low bitrates, leading to loss of detail and timbre due to the restriction of bandwidth extension techniques, which also require complex transformations and increased computational resources, particularly in mobile devices.
Innovation Solution
The implementation of Intelligent Gap Filling (IGF) technology, which reconstructs high-frequency spectral portions using frequency tiles from lower frequency ranges, allowing for full-rate core decoding and encoding in the same spectral domain without the need for downsampling or upsampling, and fills spectral gaps using parametric data and source spectral ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If bandwidth extension techniques are used to code high-frequency content at low bitrates, then audio bandwidth is maintained, but audio quality deteriorates due to loss of detail and timbre
Solution Approach 1:
The patent segments the spectral representation into frequency tiles that can be independently coded and reconstructed. By dividing the high-frequency spectrum into multiple tiles and selectively reconstructing only perceptually important ones based on energy information, the system maintains audio quality while reducing bitrate requirements for bandwidth extension.
Solution Approach 2:
The patent applies local quality by using parametric data to identify and reconstruct only the perceptually important tonal portions of the spectrum rather than uniformly reconstructing all frequency bands. This allows high-frequency content to be coded at lower quality where perceptually less critical, while maintaining high quality for important tonal elements.
2Quantity of substance
If bandwidth extension techniques are used to reconstruct high-frequency spectral portions, then audio bandwidth is maintained, but device complexity increases due to complex transformations and increased computational resources
Solution Approach 1:
The patent performs preliminary action by pre-calculating and transmitting energy information values for frequency tiles during encoding. This allows the decoder to quickly identify which tiles need reconstruction without performing complex spectral analysis in real-time, significantly reducing computational complexity for bandwidth extension on mobile devices.
Solution Approach 2:
The patent uses copying by reconstructing frequency tiles from lower-frequency counterparts when appropriate, rather than performing complex synthesis. This simpler copying operation reduces computational requirements while maintaining perceptual quality for redundant spectral information.
3Manufacturing precision
If full spectral reconstruction is performed to maintain audio quality, then audio quality is improved, but bitrate consumption increases
Solution Approach 1:
The patent applies partial action by reconstructing only the necessary portion of the high-frequency spectrum rather than performing full spectral reconstruction. By using energy information to identify and reconstruct only perceptually important frequency tiles, the system achieves acceptable audio quality at lower bitrates by leaving out redundant or less critical spectral information.
Data Source
AI summary
An apparatus for decoding an encoded audio signal having an encoded representation of a first set of first spectral portions and an encoded representation of parametric data indicating spectral energies for a second set of second spectral portions, has: an audio decoder for decoding the encoded representation of the first set of the first spectral portions to obtain a first set of first spectral portions and for decoding the encoded representation of the parametric data to obtain a decoded parametric data for the second set of second spectral portions indicating, for individual reconstruction bands, individual energies; a frequency regenerator for reconstructing spectral values in a reconstruction band having a second spectral portion using a first spectral portion of the first set of the first spectral portions and an individual energy for the reconstruction band, the reconstruction band having a first spectral portion and the second spectral portion.