Speech Frame Reconstruction With Fractional Pitch Cycle Resynchronization
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Solution Overview
Problem
Existing speech processing techniques, such as those in G.718 and G.729.1, face issues with inaccurate pulse resynchronization and inefficient computational complexity due to assumptions about integer pitch cycles, incorrect pulse positioning, and limitations in pitch lag calculation, leading to degradation in speech signal quality and increased computational overhead.
Innovation Solution
The proposed solution involves improved pulse resynchronization techniques that account for the location of the first pulse, eliminate the need for calculating the number of pulses, and combine pitch construction with sample addition or removal, using fractional pitch lags and linear changes to accurately reconstruct speech signals with both constant and changing pitches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pitch extrapolation is conducted based on the assumption of smooth pitch contour using last seven subframes, then pitch reconstruction is achieved, but computational complexity increases and accuracy decreases for non-smooth pitch contours
Solution Approach 1:
The patent applies partial action by using only the last three subframes for pitch extrapolation instead of the conventional seven subframes. This reduces computational complexity while maintaining adequate accuracy for the specific application scenario, demonstrating that excessive data collection (seven subframes) is not always necessary.
Solution Approach 2:
The patent changes the parameter of pitch lag calculation by introducing a compensation value that is added to the extrapolated pitch lag. This parameter modification allows the system to correct systematic errors in pitch reconstruction without requiring complex computational models, thereby improving accuracy while keeping computational complexity low.
2Device complexity
If integer pitch cycles are assumed for frame reconstruction, then computational complexity is reduced, but pulse positioning accuracy deteriorates
Solution Approach 1:
The patent introduces a compensation value that is added to the extrapolated pitch lag to obtain the final pitch lag used for frame reconstruction. This parameter modification compensates for the inaccuracies introduced by assuming integer pitch cycles, thereby improving pulse positioning accuracy while maintaining the computational simplicity of the integer cycle assumption.
Solution Approach 2:
The patent replaces the mechanical assumption of integer pitch cycles with a mathematical compensation mechanism. Instead of requiring complex algorithms to determine exact pulse positions, the system uses a simple additive compensation value that corrects the pitch lag, substituting a sophisticated mechanical positioning system with a straightforward mathematical adjustment.
3Reliability
If the number of pulses is calculated based on frame length and pitch period, then pulse synchronization is achieved, but errors occur when pitch cycles are non-integer values
Solution Approach 1:
The patent modifies the pitch lag parameter by adding a compensation value to the extrapolated pitch lag. This parameter change allows the system to handle non-integer pitch cycles more accurately, improving the reliability of pulse synchronization without requiring precise measurement of fractional pitch cycle values.
Solution Approach 2:
The patent applies beforehand cushioning by pre-calculating a compensation value that accounts for potential errors in pitch cycle measurement. This compensation value is stored and applied during frame reconstruction, cushioning against the errors that would otherwise occur when pitch cycles are non-integer values, thereby improving pulse synchronization reliability.
Data Source
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AI summary
An apparatus for reconstructing a frame comprising a speech signal as a reconstructed frame is provided, said reconstructed frame being associated with one or more available frames, said one or more available frames being at least one of one or more preceding frames of the reconstructed frame and one or more succeeding frames of the reconstructed frame, wherein the one or more available frames comprise one or more pitch cycles as one or more available pitch cycles. The apparatus comprises a determination unit (210) for determining a sample number difference indicating a difference between a number of samples of one of the one or more available pitch cycles and a number of samples of a first pitch cycle to be reconstructed. Moreover, the apparatus comprises a frame reconstructor (220) for reconstructing the reconstructed frame by reconstructing, depending on the sample number difference and depending on the samples of said one of the one or more available pitch cycles, the first pitch cycle to be reconstructed as a first reconstructed pitch cycle. The frame reconstructor (220) is configured to reconstruct the reconstructed frame, such that the reconstructed frame completely or partially comprises the first reconstructed pitch cycle, such that the reconstructed frame completely or partially comprises a second reconstructed pitch cycle, and such that the number of samples of the first reconstructed pitch cycle differs from a number of samples of the second reconstructed pitch cycle.