Spatial Parameter Signalling for Low-Bitrate Audio Encoding
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Solution Overview
Problem
Existing spatial audio encoding methods face challenges in efficiently managing bitrate allocation between audio signals and spatial metadata, particularly at low bitrates, leading to suboptimal quality in spatial audio reproduction.
Innovation Solution
A method and apparatus that select a single frequency band with the highest directional energy weight factor to represent spatial parameters across multiple frequency bands, reducing bitrate by transmitting only the metadata for this band, and replicating this metadata across all bands for synthesis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If spatial parameters are transmitted for each frequency band, then spatial audio quality is improved, but bitrate increases
Solution Approach 1:
The patent merges the spatial parameter information across multiple frequency bands by selecting a single representative frequency band (e.g., the band with maximum energy or maximum directional component). Instead of transmitting separate spatial parameters for each frequency band, the same spatial parameters from the representative band are applied to all bands, thereby reducing bitrate while maintaining perceptual spatial audio quality.
Solution Approach 2:
The selected spatial parameters from one frequency band serve a universal function across all frequency bands. The parameters (such as direction of arrival, energy ratios) extracted from the representative band are reused universally for synthesizing spatial audio in all other frequency bands, eliminating redundant data transmission while preserving spatial perception.
2Productivity
If spatial parameters are reduced to lower bitrate, then transmission efficiency is improved, but spatial audio quality deteriorates
Solution Approach 1:
The patent applies local quality by carefully selecting which frequency band's spatial parameters to use as the representative. The selection is based on local characteristics of each band (such as energy level or directional component strength), ensuring that the band with the most significant spatial characteristics is chosen. This local optimization ensures that the reduced-parameter representation maintains the most important spatial information.
Data Source
AI summary
An apparatus comprising means for: obtaining at least one audio signal; obtaining at least one parameter respectively for each of at least two frequency bands associated with the at least one audio signal; and selecting a frequency band of the at least two frequency bands based on comparing at least one further respective parameter for each of the at least two frequency bands wherein the at least one further respective parameter is determined from each of the at least two frequency bands; generating an output comprising a selection of the at least one parameter associated with the selected frequency band of the at least two frequency bands, such that the selection of the at least one parameter associated with the selected frequency band is configured to reduce a bitrate or size of the output.