IVAS Bitrate Distribution for Spatial Metadata and Downmix Balance
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Solution Overview
Problem
Existing codecs for immersive voice and audio services (IVAS) face challenges in optimizing bitrate distribution between mono and spatial metadata, leading to inefficiencies and bit wastage.
Innovation Solution
A method for encoding IVAS bitstreams that involves downmixing input audio signals, determining bitrate combinations and metadata quantization levels using a control table, and combining downmix channels with quantized spatial metadata to optimize bitrate distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If bitrate is allocated to spatial metadata, then immersive audio quality is improved, but mono codec overhead increases
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting metadata quantization levels based on the available bitrate. When bitrate is limited, the system changes the quantization parameters to coarser levels, reducing the metadata overhead while maintaining acceptable spatial audio quality. This resolves the contradiction by allowing flexible parameter adjustment to balance quality and overhead requirements.
2Productivity
If bitrate distribution is optimized for spatial metadata, then immersive audio performance is improved, but bit wastage occurs
Solution Approach 1:
The patent implements dynamics by making the bitrate distribution adaptive rather than static. The system dynamically determines the optimal bitrate allocation between downmix channels and spatial metadata based on current audio content characteristics and available bandwidth. This dynamic adjustment prevents bit wastage while maintaining high immersive audio performance by allocating bits only where they provide the most benefit.
Solution Approach 2:
The system changes metadata quantization parameters dynamically based on bitrate availability and audio content. By adjusting quantization levels adaptively, the patent ensures that bits are not wasted on excessive precision where it is not needed, while still maintaining high performance where quality is critical. This parameter adaptation resolves the contradiction between performance and bit efficiency.
3Measurement precision
If detailed spatial metadata is encoded, then audio immersion quality is improved, but bitrate consumption increases
Solution Approach 1:
The patent directly addresses this contradiction through parameter changes in metadata quantization. The system selects appropriate quantization levels from a set of predefined options based on the available bitrate. When bitrate is abundant, finer quantization levels are used for higher precision. When bitrate is constrained, coarser quantization levels reduce bitrate consumption while maintaining acceptable quality. This dynamic parameter adjustment resolves the trade-off between precision and bitrate consumption.
Data Source
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AI summary
Embodiments are disclosed for bitrate distribution in immersive voice and audio services. In an embodiment, a method of encoding an IVAS bitstream comprises: receiving an input audio signal; downmixing the input audio signal into one or more downmix channels and spatial metadata; reading a set of one or more bitrates for the downmix channels and a set of quantization levels for the spatial metadata from a bitrate distribution control table; determining a combination of the one or more bitrates for the downmix channels; determining a metadata quantization level from the set of metadata quantization levels using a bitrate distribution process; quantizing and coding the spatial metadata using the metadata quantization level; generating, using the combination of one or more bitrates, a downmix bitstream for the one or more downmix channels; combining the downmix bitstream, the quantized and coded spatial metadata and the set of quantization levels into the IVAS bitstream.