Audio Decoder SBR Mode Switching for Lower HBE Workload
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Solution Overview
Problem
Existing HE-AACv2 decoders supporting MPEG-4 SBR enhancements face significant workload increases due to the introduction of Harmonic Bandwidth Extension (HBE), even in legacy bitstreams lacking SBR Enhancements, leading to increased complexity and delay, particularly undesirable for battery-operated devices.
Innovation Solution
Implement a dual spectral band replication mode in the decoder, where a second spectral band replication module is configured to operate based on side information, allowing it to be deactivated when not needed, reducing unnecessary processing operations and maintaining a default state until explicit activation signals are detected.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If HBE processing is enabled in HE-AACv2 decoder to support MPEG-4 SBR enhancements, then spectral band replication quality is improved, but computational workload and complexity increase significantly
Solution Approach 1:
The patent implements dynamic switching between HBE processing mode and legacy SBR patching mode based on bitstream indicators. The decoder can adaptively enable or disable the computationally intensive HBE algorithm depending on whether the encoded audio signal requires enhanced spectral band replication, thereby resolving the contradiction between quality and complexity.
2Manufacturing precision
If HBE processing is enabled in HE-AACv2 decoder, then spectral band replication quality is improved, but processing delay increases by one frame
Solution Approach 1:
The patent enables dynamic mode selection where the decoder can switch between HBE processing (with one-frame delay) and legacy SBR patching (without additional delay) based on the encoded audio signal characteristics. This allows the system to minimize processing delay by using the simpler legacy method when enhanced quality is not required.
3Adaptability or versatility
If second spectral band replication module is always active to support SBR enhancements, then compatibility with enhanced bitstreams is improved, but computational workload increases for legacy bitstreams
Solution Approach 1:
The patent implements a dynamically controllable second spectral band replication module that can be activated or deactivated based on indicators in the encoded audio signal. When processing legacy bitstreams without SBR enhancement indicators, the module remains deactivated, maintaining high decoding efficiency. When enhanced bitstreams are detected, the module activates to provide compatibility and improved spectral band replication quality.
Solution Approach 2:
The patent extracts and processes only the necessary components from the encoded audio signal to determine whether HBE processing is required. By checking specific indicators in the bitstream, the decoder can selectively engage the computationally intensive second spectral band replication module only when needed, rather than always processing all possible enhancements.
Data Source
AI summary
An apparatus for audio decoding according to an embodiment is provided. The apparatus comprises a decoding module for decoding a received encoded audio signal to obtain a decoded audio signal having a first bandwidth. Moreover, the apparatus comprises a first spectral band replication module for conducting spectral band replication according to a first spectral band replication mode to obtain a spectral band replicated audio signal. Furthermore, the apparatus comprises a second spectral band replication module for conducting spectral band replication according to a second spectral band replication mode to obtain the spectral band replicated audio signal, wherein the second spectral band replication mode is different from the first spectral band replication mode.