Audio Codec LSB Adaptation for Bitrate-Quality Tradeoffs
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing audio codecs face challenges in achieving an optimal tradeoff between audio quality, complexity, and bitrate, particularly at high bitrates where truncating high-frequency coefficients can severely degrade performance.
Innovation Solution
An audio decoder and encoder that selectively omits the encoding and decoding of least significant bits for spectral values, while ensuring that most significant bits are encoded and decoded, allowing for a flexible adaptation to bit budget constraints and maintaining good audio quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If least significant bits are encoded for all spectral values, then audio quality is improved, but bitrate increases
Solution Approach 1:
The patent applies local quality by differentiating the encoding treatment of spectral values based on their frequency characteristics. Least significant bits are selectively encoded for spectral values in frequency ranges where they contribute meaningfully to audio quality, while being omitted in ranges where their contribution is negligible. This allows the system to allocate bitrate resources non-uniformly across the frequency spectrum, improving overall audio quality per bit rather than applying uniform encoding to all spectral values.
2Quantity of substance
If high-frequency coefficients are truncated to reduce bitrate, then bitrate is reduced, but audio quality severely degrades at high bitrates
Solution Approach 1:
The patent implements partial action by selectively applying least significant bit encoding to only those spectral values where it provides meaningful improvement. Rather than encoding least significant bits for all spectral values (excessive action) or truncating high-frequency coefficients entirely (insufficient action), the system identifies and encodes least significant bits only for spectral values in frequency ranges and under conditions where they contribute to audio quality, achieving an optimal partial application of the encoding process.
Solution Approach 2:
The patent changes the encoding parameter (number of bits) dynamically based on the spectral value's frequency range and other characteristics. For spectral values in certain frequency ranges, the encoder uses fewer bits by omitting least significant bits, while for other spectral values, full precision including least significant bits is maintained. This parameter adaptation allows the system to optimize the tradeoff between bitrate and audio quality on a per-spectral-value basis rather than applying a fixed encoding scheme.
3Measurement precision
If full encoding of all spectral values is performed, then audio quality is maintained, but complexity increases
Solution Approach 1:
The patent extracts and processes only the most relevant components of spectral values for encoding. By identifying and separately handling the most significant bits versus least significant bits, the system can extract only the essential information that contributes to audio quality and encode selectively. This extraction approach simplifies the encoding process by focusing computational resources on the most impactful bits rather than uniformly processing all bits of all spectral values.
Data Source
AI summary
An audio decoder for providing a decoded audio information on the basis of an encoded audio information is configured to obtain decoded spectral values on the basis of an encoded information representing the spectral values. The audio decoder is configured to jointly decode two or more most significant bits per spectral value on the basis of respective symbol codes for a set of spectral values using an arithmetic decoding, wherein a respective symbol code represents two or more most significant bits per spectral value for one or more spectral values. The audio decoder is configured to decode one or more least significant bits associated with one or more of the spectral values in dependence on how much least significant bit information is available, such that one or more least significant bits associated with one or more of the spectral values are decoded.