Voice Decoder Switching With High-Frequency Noise Fill
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Solution Overview
Problem
Existing voice transmission systems experience auditory discomfort due to noise and discontinuities when switching between wide-band and narrow-band codecs, particularly because switching cannot be performed until a silence period, which is inconvenient.
Innovation Solution
A voice signal decoding device and method that includes a first decoder, a second decoder, a signal switch, and a noise adder, where the noise adder adds a noise signal to the high-frequency band of the output signal from the second decoder when switching from a wide-band to a narrow-band codec, and cross fade processing is used to smooth the transition, reducing auditory discomfort.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If codec switching is performed in a silence period to prevent noise, then auditory comfort is improved, but switching cannot be performed until silence occurs which reduces operational flexibility and increases waiting time
Solution Approach 1:
The patent applies preliminary action by adding noise to the high-frequency band before the actual codec switching occurs. This prepares the auditory system in advance for the upcoming bandwidth reduction, so that when the narrow-band codec signal is switched in, the listener is not surprised by the abrupt loss of high-frequency content. The noise addition is performed on the narrow-band decoded signal prior to switching, smoothing the transition and eliminating the need to wait for a silence period.
2Ease of operation
If codec switching is performed immediately to improve operational flexibility, then switching speed is improved, but noise and discontinuities occur causing auditory discomfort
Solution Approach 1:
The patent uses noise addition as an intermediary element between the wide-band and narrow-band codec signals. When switching from wide-band to narrow-band, noise is added to the narrow-band decoded signal in the high-frequency band. This noise acts as a mediator that bridges the gap between the two different bandwidth signals, smoothing the transition and preventing the abrupt discontinuities that would otherwise cause auditory discomfort. This allows immediate switching without the harmful effects.
3Measurement precision
If wide-band codec is used to maintain signal quality, then audio fidelity is improved, but bandwidth consumption increases
Solution Approach 1:
The patent implements dynamic codec switching that adapts to network conditions. The system can switch between wide-band and narrow-band codecs based on available bandwidth and transmission conditions. When network conditions are good, the wide-band codec provides high audio fidelity. When bandwidth is constrained, the system switches to narrow-band codec with noise addition to maintain acceptable quality. This dynamic adaptation allows the system to optimize the trade-off between audio fidelity and bandwidth consumption in real-time.
Data Source
AI summary
A voice signal decoding device includes a first decoder, a second decoder, a signal switch, and a noise adder. The first decoder decodes first encoded data encoded by a first encoding method. The second decoder decodes second encoded data encoded by a second encoding method. The second encoded data has a narrower band than a band of the first encoded data. The signal switch switches an output signal of the first decoder and an output signal of the second decoder. The noise adder adds a noise signal to a high-frequency band in the output signal of the second decoder when the signal switch switches an output signal from the output signal of the first decoder to the output signal of the second decoder. The high-frequency band is a band where a signal component is lacking as compared with the output signal of the first decoder.