Bit Reservoir Control for Audio Metadata Fluctuations
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Solution Overview
Problem
ABR audio coding systems face challenges in maintaining consistent audio quality due to varying amounts of metadata, which impact bit allocation and affect the overall bitrate.
Innovation Solution
The implementation of a bit allocation scheme that utilizes a virtual bit reservoir for metadata, decoupling its fluctuations from audio data bit allocation, ensuring consistent audio quality by dynamically adjusting bit allocation based on fill levels and thresholds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single bit reservoir is used for both audio data and metadata, then the bit allocation mechanism becomes simple, but metadata fluctuations directly impact audio quality consistency
Solution Approach 1:
The patent divides the single bit reservoir into two separate virtual reservoirs: one dedicated to metadata and another to audio data. This segmentation allows independent bit allocation control for each data type, preventing metadata variations from directly impacting audio quality while maintaining overall bitrate constraints.
Solution Approach 2:
The patent introduces virtual reservoirs as intermediary layers between the actual bitstream and the encoding process. These virtual reservoirs act as buffers that decouple the coupling between metadata and audio data bit allocation, allowing the system to maintain audio quality consistency even when metadata size varies.
2Adaptability or versatility
If bits are dynamically allocated based on overall bit reservoir fill level, then the system can adapt to varying bitrate requirements, but audio quality becomes sensitive to metadata size variations
Solution Approach 1:
The patent segments the bit allocation process into two independent virtual reservoirs, allowing the system to adapt overall bitrate while maintaining consistent audio quality. The metadata reservoir absorbs size variations, while the audio reservoir maintains stable allocation levels.
Solution Approach 2:
The patent performs preliminary bit allocation decisions by maintaining virtual reservoirs that predict future bit availability. This allows the system to pre-determine audio bit allocation based on expected metadata sizes, ensuring consistent audio quality before actual encoding occurs.
3Device complexity
If the bit reservoir is shared between metadata and audio data, then the system structure remains simple, but perceived audio quality deteriorates during metadata fluctuations
Solution Approach 1:
The patent segments the shared bit reservoir into separate virtual reservoirs for metadata and audio data. This segmentation protects audio quality from metadata fluctuations while maintaining manageable system complexity through virtual abstraction.
Solution Approach 2:
The patent creates virtual copies of the bit reservoir structure, where virtual reservoirs mirror the functionality of a physical reservoir but operate independently for metadata and audio data. This copying approach isolates audio quality from metadata variations without requiring physically separate reservoirs.
Data Source
AI summary
The present document describes a method for allocating bits to a frame of a sequence of frames to yield a bitstream having a constant average bitrate, wherein the frame comprises audio data and metadata. The method comprises maintaining an overall bit reservoir and maintaining a virtual bit reservoir being a subset of the overall bit reservoir, such that bits for the metadata of the frame are allocated from the virtual bit reservoir and such that bits for the audio data of the frame are allocated from the overall bit reservoir.