Spatial Audio Parameter Merging Across Time-Frequency Bands
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Solution Overview
Problem
Existing spatial audio codecs face challenges in efficiently compressing spatial metadata at varying bit rates, particularly at lower bitrates, due to the high raw bitrate of encoded parameters, necessitating a need for apparatus and methods to optimize codec performance by reducing the metadata without compromising quality.
Innovation Solution
The proposed solution involves determining a merge metric to control the merging of spatial audio signal parameter values over the time-frequency domain, using onset metrics and energy ratios to select a smaller number of representative parameter values, and encoding these values to reduce the metadata footprint.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If spatial metadata parameters are encoded with high precision for each frequency band, then measurement precision is improved, but bitrate increases excessively
Solution Approach 1:
The patent merges spatial metadata parameters across adjacent frequency bands by determining representative parameter values that apply to multiple bands. This is achieved by evaluating merge metrics that compare parameter similarity between bands, and when similarity exceeds a threshold, parameters are merged to a single representative value, thereby reducing the total number of parameters to encode while maintaining spatial accuracy.
Solution Approach 2:
The patent implements dynamic parameter merging where the degree of merging adapts based on the content characteristics. Merge decisions are made dynamically by calculating merge metrics for each pair of frequency bands and comparing against thresholds, allowing the system to maintain high precision when needed and reduce bitrate when parameters are similar across bands.
2Productivity
If spatial metadata is compressed aggressively to reduce bitrate, then productivity is improved, but measurement precision deteriorates
Solution Approach 1:
The patent employs feedback mechanisms where merge decisions are based on calculated merge metrics that evaluate the impact of merging on spatial accuracy. The system continuously monitors parameter similarity across frequency bands and adjusts merging decisions accordingly, ensuring that compression does not degrade spatial metadata quality below acceptable thresholds.
Solution Approach 2:
The patent changes parameters dynamically based on content characteristics. Merge thresholds and representative value selections are adjusted according to the measured similarity between frequency bands, allowing optimal balance between compression efficiency and spatial accuracy for different audio content types.
3Reliability
If spatial audio parameters are maintained at full resolution across all frequency bands, then reliability is improved, but device complexity increases
Solution Approach 1:
The patent segments the frequency spectrum into bands that are candidates for merging. By dividing the frequency range and evaluating merge metrics between adjacent segments, the system identifies opportunities to reduce parameters without compromising overall audio quality, thereby simplifying processing while maintaining reliability.
4Measurement precision
If merge metric calculation is performed for all frequency band pairs, then measurement precision is improved, but loss of time increases
Solution Approach 1:
The patent performs merge metric calculations selectively rather than for all possible frequency band pairs. By evaluating only adjacent or near-adjacent bands and using threshold-based early termination, the system achieves sufficient merge decision accuracy without the computational burden of exhaustive comparisons, thereby reducing encoding time.
Data Source
AI summary
An apparatus comprising means configured to: obtain at least one audio signal; obtain, for the at least one audio signal, spatial audio signal parameter values, the spatial audio signal parameters values distributed within a time-frequency domain; determine a merge metric to control a merging of the spatial audio signal parameter values over the time-frequency domain; and merge, based on the merge metric, the spatial audio signal parameter values to a smaller number of spatial audio signal parameter values over time and/or frequency within the time-frequency domain.