Master Scale Factor Band Table Design for Audio HFR
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Solution Overview
Problem
Existing audio decoding technologies face challenges in determining scale factor bands for high frequency reconstruction in a computationally and bit rate efficient manner, leading to increased costs and signaling overhead in audio encoding and decoding processes.
Innovation Solution
A system that generates a master scale factor band table using pre-determined scale factor band tables and parameters, allowing for the selection of scale factor bands to approximate the spectral envelope of the highband signal, reducing computational load and signaling overhead by using static tables and parameters transmitted in the bitstream.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If dynamic scale factor band tables are determined through complex calculations, then the spectral envelope approximation accuracy is improved, but the computational cost and device complexity increase
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing scale factor band tables during the encoding phase. The encoder determines comprehensive scale factor band tables in advance and transmits them to the decoder, eliminating the need for the decoder to perform complex real-time calculations. This shifts the computational burden to the encoding phase, allowing the decoder to simply retrieve and use the pre-computed tables, thereby reducing decoder complexity while maintaining spectral envelope approximation accuracy.
2Measurement precision
If detailed scale factor band tables with fine frequency resolution are used, then the spectral envelope approximation accuracy is improved, but the bit rate overhead increases
Solution Approach 1:
The patent applies dynamics by making the scale factor band table structure adaptive to the specific audio signal characteristics. The encoder analyzes the input signal and dynamically determines an appropriate scale factor band table configuration that matches the signal's spectral properties. This allows the system to use detailed tables only when necessary for accurate spectral envelope approximation, while using coarser tables for signals that don't require fine resolution, thereby optimizing the trade-off between accuracy and bit rate overhead.
Solution Approach 2:
The patent applies parameter changes by allowing the scale factor band tables to be configured with different frequency resolutions and band groupings based on signal characteristics. The encoder can select and transmit tables with appropriate frequency bin allocations and scale factor band definitions that match the current audio content, rather than always using the finest resolution. This dynamic parameter adjustment reduces bit rate overhead while maintaining sufficient approximation accuracy for the given signal type.
3Productivity
If pre-determined static scale factor band tables are used, then the computational cost and signaling overhead are reduced, but the adaptability to different signal characteristics decreases
Solution Approach 1:
The patent applies universality by designing a system where a single pre-determined scale factor band table can serve multiple signal types and conditions. The encoder selects from a set of pre-defined table configurations that are designed to be broadly applicable across different audio content. Additionally, the system can combine multiple tables or use table subsets that work effectively for various signal characteristics, making the pre-computed tables universally useful while maintaining decoding efficiency.
Data Source
AI summary
The present document relates to audio encoding and decoding. In particular, the present document relates to audio coding schemes which make use of high frequency reconstruction (HFR) methods. A system configured to determine a master scale factor band table of a highband signal (105) of an audio signal is described. The highband signal (105) is to be generated from a lowband signal (101) of the audio signal using a high frequency reconstruction (HFR) scheme. The master scale factor band table is indicative of a frequency resolution of a spectral envelope of the highband signal (105).