Binaural Audio Decoding in the Transform Domain
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Solution Overview
Problem
Existing methods for converting downmixed audio channels into binaural output channels are inefficient, leading to increased computational complexity and sound quality degradation due to the need for multiple transformations and the production of intermediary channels, making it difficult to implement in portable devices like MP3 players.
Innovation Solution
A spatial decoder unit that directly synthesizes binaural channels from downmixed audio channels and spatial parameters in the transform domain, eliminating the need for additional intermediary channels and reducing computational requirements by processing perceptual transfer functions in the parameter domain, thereby reducing the number of necessary transformations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If downmixed audio channels are converted into binaural output channels using existing methods, then binaural output is achieved, but computational complexity increases and sound quality degrades due to multiple transformations and intermediary channels
Solution Approach 1:
The patent combines the spatial decoding process and binaural synthesis process into a single integrated device. The spatial decoder unit directly generates binaural output channels from downmixed audio channels without producing separate intermediary channels, merging two previously separate processing stages into one unified operation that reduces computational overhead and improves efficiency
Solution Approach 2:
The patent extracts and eliminates the unnecessary intermediary channel generation step from the processing chain. By directly synthesizing binaural channels from downmixed channels through a single spatial decoding operation, the method removes the redundant expansion to multiple intermediary channels and subsequent reduction back to two channels, thereby reducing computational complexity
2Reliability
If downmixed audio channels are converted into binaural output channels using existing methods, then binaural output is achieved, but the process requires multiple transformations producing intermediary channels
Solution Approach 1:
The patent merges the spatial decoding and binaural synthesis operations into a single integrated process. The spatial decoder unit performs both functions simultaneously, directly producing binaural output channels from downmixed input channels without requiring separate transformation stages, thereby reducing the total number of transformations required
3Reliability
If existing conversion methods are used, then binaural output channels are produced, but artifacts increase and sound quality decreases
Solution Approach 1:
The patent extracts and eliminates the intermediary channel generation step that causes artifacts. By directly synthesizing binaural channels through a single spatial decoding operation without expanding to multiple intermediary channels first, the method removes the source of artifacts that occur during expansion and subsequent reduction operations
4Adaptability or versatility
If the conversion process is implemented in portable devices, then binaural audio is available, but computational requirements exceed available resources
Solution Approach 1:
The patent combines spatial decoding and binaural synthesis into a single efficient operation that reduces computational requirements. By eliminating the need to generate and process multiple intermediary channels, the integrated approach reduces the computational load to a level suitable for implementation in resource-constrained portable devices like MP3 players
Solution Approach 2:
The patent changes the processing approach from time-domain convolution to frequency-domain multiplication with HRTF filters. This parameter change in the domain of processing significantly reduces computational complexity, making the implementation feasible for portable devices with limited processing power
Data Source
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AI summary
A spatial decoder unit (23) is arranged for transforming one or more audio channels (s; 1, r) into a pair of binaural output channels (Ib, rb). The device comprises a parameter conversion unit (234) for converting the spatial parameters (sp) into binaural parameters (bp) containing binaural information. The device additionally comprises a spatial synthesis unit (232) for transforming the audio channels (L, R) into a pair of binaural signals (Lb, Rb) while using the binaural parameters (bp). The spatial synthesis unit (232) preferably operates in a transform domain, such as the QMF domain.