Spatial Audio Metadata Quantization for Bitrate-Constrained Encoding
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Solution Overview
Problem
Existing spatial audio encoding methods face challenges in efficiently encoding and quantizing directional components such as elevation, azimuth, and energy ratio parameters for multi-channel audio signals, particularly when the bitrate exceeds the codec's allowed limit, leading to suboptimal quality and inefficiencies in transmission.
Innovation Solution
A method is proposed to improve the quality of encoded and quantized metadata by adjusting quantization resolution and reordering sub-bands, reducing bit allocation through techniques like entropy encoding and implicit signaling, and optimizing bit usage by reordering and reducing quantization resolution only for sub-bands that exceed the allowed bitrate, without re-estimating entropy coding bits or additional signaling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If quantization resolution is increased to improve spatial audio quality, then encoding quality is improved, but bitrate consumption increases
Solution Approach 1:
The patent segments the audio signal into multiple frequency sub-bands and processes each sub-band independently with different quantization resolutions. This allows high quantization resolution (high quality) to be applied only to sub-bands where it is perceptually necessary, while using lower resolution for other sub-bands, thereby reducing overall bitrate while maintaining spatial audio quality.
Solution Approach 2:
The patent applies different quantization resolutions to different frequency sub-bands based on their specific characteristics and perceptual importance. Instead of using a uniform quantization resolution across all sub-bands, the system optimizes the quantization precision locally for each sub-band, achieving high quality where needed while minimizing bitrate consumption elsewhere.
2Quantity of substance
If quantization resolution is decreased to reduce bitrate, then bitrate consumption is reduced, but spatial audio quality deteriorates
Solution Approach 1:
The patent applies high quantization resolution only partially to specific frequency sub-bands where it provides the most perceptual benefit, rather than applying it excessively to all sub-bands. This selective approach ensures adequate spatial audio quality is maintained while significantly reducing overall bitrate consumption compared to uniform high-resolution encoding.
3Ease of manufacture
If uniform quantization resolution is applied to all sub-bands, then encoding simplicity is maintained, but bit usage efficiency is reduced
Solution Approach 1:
The patent dynamically changes the quantization resolution parameter for different frequency sub-bands based on their spectral characteristics and perceptual importance. This parameter adaptation allows the system to achieve superior bit usage efficiency compared to uniform quantization, while the changes are implemented through automated analysis and selection processes that maintain encoding simplicity.
4Productivity
If additional signaling is implemented to optimize bit allocation, then bit usage efficiency is improved, but device complexity increases
Solution Approach 1:
The patent implements a self-service mechanism where the encoding system automatically analyzes the spectral characteristics of each sub-band and autonomously determines the optimal quantization resolution and bit allocation without requiring external control or complex signaling. This self-optimizing approach improves bit usage efficiency while minimizing device complexity by eliminating the need for additional control signaling infrastructure.
Data Source
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AI summary
An apparatus comprising means configured to: generate spatial audio signal directional metadata parameters for a block of time-frequencies; generate encoded spatial audio signal directional metadata parameters (108) for a block of time-frequencies based on a first quantization resolution (203); compare a number of bits used for the encoded spatial audio signal directional parameters (108) for the block of time-frequencies based on the first quantization resolution against a determined number of bits; output or store the encoded spatial audio signal directional metadata parameters for a block of time-frequencies (108) based on a first quantization resolution when the number of bits used for the encoded spatial audio signal directional parameters for the block of time-frequencies (108) based on the first quantization resolution is less than a determined number of bits (217); generate encoded spatial audio signal directional metadata parameters (108) for the block of time-frequencies based on a second quantization resolution when the number of bits used for the encoded spatial audio signal directional parameters for the block of time-frequencies (108) based on the first quantization resolution is more than the determined number of bits and a difference between the determined number of bits and the number of bits used for the encoded spatial audio signal directional parameters (108) for the block of time-frequencies based on the first quantization resolution is less than a determined number of bits is within a determined threshold (217); generate encoded spatial audio signal directional metadata parameters (108) for the block of time-frequencies based on a third quantization resolution when the number of bits used for the encoded spatial audio signal directional parameters (108) for the block of time-frequencies based on the first quantization resolution is more than the determined number of bits and the difference between the determined number of bits and the number of bits used for the encoded spatial audio signal directional parameters (108) for the block of time-frequencies based on the first quantization resolution is greater than the determined threshold, wherein the third quantization resolution is determined such that a number of bits used for the encoded spatial audio signal directional parameters for the block of time-frequencies based on the third quantization resolution is always equal to or less than the determined number of bits (217).