Audio Bit Allocation via Subband Grouping
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Solution Overview
Problem
Current audio coding technologies face inefficiencies in bit allocation, particularly at low bit rates, leading to random and discontinuous quantization across frames, which affects audio quality and coding efficiency.
Innovation Solution
The method involves grouping frequency bands based on signal characteristics and energy attributes, allowing for more concentrated and continuous bit allocation across frames, optimizing bit distribution to important audio bands and reducing discontinuity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If bits are allocated to all bands in a cyclic and iterative manner according to normalized energy, then bit allocation is performed across the entire frequency spectrum, but the allocation result becomes random and discrete, causing discontinuous quantization between frames
Solution Approach 1:
The patent divides the frequency bands into multiple groups, where each group contains multiple subbands. Instead of allocating bits to all individual subbands globally, the patent performs bit allocation at the group level. This segmentation approach reduces the randomness and discreteness of bit allocation, ensuring more continuous quantization across frames while maintaining adaptability through group-based energy normalization.
2Ease of manufacture
If a smallest unit of bits equal to bandwidth value is used during allocation, then integer number of bits is allocated to each band, but bits cannot be allocated to many bands and excessive bits are allocated to another band, reducing coding efficiency at low bit rates
Solution Approach 1:
The patent segments the frequency spectrum into groups of subbands. By allocating bits to groups rather than individual subbands, the system achieves finer-grained control over bit distribution. This allows more flexible allocation where bits can be efficiently distributed across multiple bands without being constrained by the bandwidth value minimum, thereby improving coding efficiency at low bit rates while maintaining allocation simplicity.
3Adaptability or versatility
If global bit allocation is performed across all bands, then overall bit distribution is achieved, but partial discontinuity occurs in the allocation between frames
Solution Approach 1:
The patent divides the global bit allocation problem into smaller group-level allocation problems. Each group of subbands is processed independently with its own energy normalization and bit allocation. This segmentation ensures that allocation decisions are more stable across frames since groups maintain consistency, while still achieving global coverage through the collective allocation across all groups.
Solution Approach 2:
The patent introduces groups as intermediary entities between individual subbands and the global bit allocation system. These groups act as mediators that aggregate subbands with similar characteristics, providing a stable intermediate level for bit allocation decisions. This intermediary structure reduces frame-to-frame variability while maintaining comprehensive coverage through the hierarchical group-subband relationship.
Data Source
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AI summary
Embodiments of the present invention provide a method and an apparatus for allocating bits in an audio signal. The method for allocating bits in an audio signal includes: dividing a frequency band of an audio signal into a plurality of subbands, quantizing a subband normalization factor of each subband; grouping the plurality of subbands into a plurality of groups, and acquiring a group parameter of each group, where the group parameter is used to represent a signal characteristic and an energy attribute of an audio signal of the corresponding group; allocating coding bits to at least one group according to the group parameter of each group, where a sum of coding bits allocated to the at least one group is the number of coding bits of the audio signal; and allocating the coding bits allocated to the at least one group to each subband in each group of the at least one group according to the subband normalization factor of each subband in each group of the at least one group. In a case of a low or medium bit rate, the embodiments of the present invention can, by means of grouping, ensure relatively stable allocation of previous and subsequent frames and reduce impact of global allocation on partial discontinuity.