Audio Decoder Energy Continuity in Frame Erasure
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Solution Overview
Problem
Existing speech decoding apparatuses fail to maintain signal energy continuity during frame erasure concealment processing, leading to deteriorated sound quality due to the lack of consideration for energy evolution in past signals.
Innovation Solution
A speech decoding apparatus with an adaptive codebook that calculates and utilizes energy change between subframes to determine the adaptive codebook gain, generating repaired frames that maintain energy evolution, and incorporates a noise applying section to modify excitation vectors, ensuring energy consistency and reducing sound break perception.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If pitch gain is attenuated at a fixed ratio for frame erasure concealment processing, then the processing is simple, but energy evolution of the signal is not taken into consideration and pitch gain is attenuated at a fixed rate, making the concealed frame less likely to hold continuity in energy from the past signal and likely to have the feeling of sound break
Solution Approach 1:
The patent applies dynamics by changing the pitch gain attenuation from a fixed ratio to a dynamic process that adapts to signal characteristics. Specifically, the attenuation ratio is adjusted based on the energy evolution of the signal in past frames, allowing the system to adapt its behavior to match the actual signal patterns rather than using a static attenuation factor.
Solution Approach 2:
The patent changes the parameter used for pitch gain attenuation from a fixed constant to a variable derived from signal energy analysis. By calculating energy evolution metrics from past signal frames and using these to determine the attenuation ratio, the system transforms a static parameter into a dynamic one that reflects actual signal characteristics.
2Device complexity
If pitch gain is attenuated at a fixed ratio regardless of energy evolution, then the processing complexity is low, but sound quality of the decoded signal deteriorates due to lack of energy evolution consideration
Solution Approach 1:
The patent introduces energy evolution parameters derived from past signal frames to control the pitch gain attenuation process. By calculating energy metrics and using them to adjust the attenuation ratio dynamically, the system adds complexity only where needed—to maintain energy continuity—rather than applying complex processing uniformly.
Solution Approach 2:
The patent implements feedback by using the energy evolution characteristics of past signal frames to adjust the pitch gain attenuation for current and future frames. This creates a closed-loop system where the attenuation process continuously adapts based on observed signal behavior, improving sound quality through responsive adjustment rather than fixed processing.
3Ease of manufacture
If pitch gain is attenuated at a fixed rate, then the processing is straightforward, but the concealed frame is less likely to hold continuity in energy from the past signal
Solution Approach 1:
The patent changes the attenuation parameter from a fixed value to a dynamically calculated value based on signal energy evolution. By deriving the attenuation ratio from energy metrics of past frames, the system maintains ease of implementation through straightforward calculations while achieving stable energy continuity in the concealed frames.
Data Source
AI summary
There is disclosed an audio decoding device capable of improving audio quality of a decoded signal by considering the energy change of a past signal in eracure concealment processing. In this device, an energy change calculation unit (143) calculates an average energy of an audio source signal of one-pitch cycle from the end of the ACB vector outputted from an adaptive codebook (106). Moreover, the energy change calculation unit (143) calculates a ratio of the average energy of the current sub-frame and the sub-frame immediately before and outputs the ratio to an ACB gain generation unit (135). The ACB gain generation unit (135) outputs a conceal processing ACB gain defined by the ACB gain decoded in the past or information on the energy change ratio outputted from the energy change calculation unit (143) to a multiplier (132).