Transient Audio Encoding with Time Envelope Shaping for Pre-Echo Reduction
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Solution Overview
Problem
Current bandwidth extension methods for speech signals, particularly for transient signals, suffer from pre-echo artifacts due to inadequate modification of the time envelope during encoding, leading to unsatisfactory recovery at the decoding end.
Innovation Solution
The method involves modifying the time envelope of transient signals to enhance the difference in amplitude values between sub-frames, allowing for more distinct characterization and improved encoding without increasing the number of bits required, thereby enhancing the quality of transient signal recovery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the time envelope of transient signals is not modified during encoding, then the encoding process is simple, but pre-echo artifacts occur and transient signal recovery quality deteriorates
Solution Approach 1:
The patent applies preliminary action by modifying the time envelope before the main encoding process. Specifically, it performs attack processing on the time envelope to suppress pre-echo artifacts before transform coding occurs. This advance modification prevents the harmful effects from manifesting in the final decoded signal.
Solution Approach 2:
The patent changes parameters of the time envelope by adjusting its amplitude characteristics during attack portions. It modifies the time envelope parameters to reduce pre-echo while preserving the transient signal's essential characteristics, thereby improving recovery quality without fundamentally changing the encoding structure.
2Productivity
If conventional transform coding is used for transient signals, then bit rate efficiency is maintained, but transient characteristics are distorted and pre-echo artifacts are generated
Solution Approach 1:
The patent applies local quality by treating different portions of the signal differently. It identifies attack portions (transient regions) and applies specific modification only to those regions' time envelopes, while leaving other portions unchanged. This localized approach preserves transient characteristics without compromising overall bit rate efficiency.
Solution Approach 2:
The patent changes parameters of the time envelope specifically in attack portions by reducing the amplitude of pre-echo components. This parameter modification allows the signal to maintain better transient characteristics while still using efficient transform coding for the overall signal representation.
3Device complexity
If the time envelope amplitude differences are not enhanced, then the encoding complexity is low, but the distinction between transient peaks and other sub-frames is insufficient leading to poor recovery
Solution Approach 1:
The patent performs preliminary modification of the time envelope to enhance amplitude differences before encoding. By pre-processing the time envelope to emphasize transient peaks, the system improves characterization accuracy without adding complex processing during the main encoding stage.
Solution Approach 2:
The patent changes parameters of the time envelope by adjusting amplitude values to enhance the distinction between transient peaks and other sub-frames. This parameter modification improves the precision of transient signal characterization while maintaining relatively simple encoding complexity.
Data Source
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AI summary
A transient signal encoding method and device, decoding method and device, and processing system are provided. The transient signal encoding method includes: obtaining a reference sub-frame where a maximal time envelope having a maximal amplitude value is located from time envelopes of all sub-frames of an input transient signal (11); adjusting an amplitude value of the time envelope of each sub-frame before the reference sub-frame in such a way that a first difference is greater than a preset first threshold, in which the first difference is a difference between the amplitude value of the time envelope of each sub-frame before the reference sub-frame and the amplitude value of the maximal time envelope (13); and writing the adjusted time envelope into bitstream (15).