Audio Encoding Device Dynamic Time Warping Pitch Node Control
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Solution Overview
Problem
Existing audio coding technologies face challenges in accurately detecting pitch contours, leading to sound quality deterioration and inefficient bit usage, especially when dealing with large pitch changes, as they rely on fixed tables that require more bits for coding pitch ratio information, which is costly in low bit-rate scenarios.
Innovation Solution
A dynamic time warping scheme that includes a pitch contour detection unit, a dynamic time warping unit to determine the number of pitch nodes and generate a first time warping parameter, and a multiplexer to combine this parameter with the coded audio signal, allowing for efficient coding and decoding without a large fixed table, even with large pitch changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a fixed table is used to code pitch ratio information, then pitch correction can be achieved, but the number of bits required for coding increases
Solution Approach 1:
The patent applies dynamics by making the time warping parameter table variable rather than fixed. The table size and granularity are dynamically adjusted based on the detected pitch contour characteristics. When pitch changes are large, a coarser table is used to reduce bit rate; when pitch changes are subtle, a finer table provides better accuracy. This dynamic adaptation resolves the contradiction between precision and bit rate efficiency.
Solution Approach 2:
The patent changes parameters by adapting the time warping parameter table based on pitch contour analysis. The table selection and configuration are modified according to the actual pitch variation patterns in the audio signal. This parameter adaptation allows the system to use minimal bits while maintaining accurate pitch correction by matching the table characteristics to the signal characteristics.
2Productivity
If time warping is applied to correct pitch changes, then coding efficiency improves, but accuracy of pitch contour detection becomes critical and difficult to achieve
Solution Approach 1:
The patent implements feedback by using the detected pitch contour to adaptively configure the time warping parameter table, which then processes the audio signal, and the result feeds back into refining the pitch contour detection. This closed-loop approach allows the system to improve detection accuracy iteratively while maintaining coding efficiency through adaptive parameter selection.
Solution Approach 2:
The patent applies preliminary action by performing pitch contour detection and analyzing pitch variation patterns before selecting and applying the appropriate time warping parameter table. This preliminary analysis enables the system to prepare the optimal coding parameters in advance, ensuring both high coding efficiency and accurate pitch correction without requiring perfect initial detection.
3Manufacturing precision
If the number of pitch nodes is increased to improve pitch correction accuracy, then sound quality improves, but the number of bits required for coding the time warping parameter increases
Solution Approach 1:
The patent applies local quality by using different numbers of pitch nodes in different regions of the time warping parameter table based on local pitch variation characteristics. Rather than uniformly increasing pitch nodes throughout, the system concentrates computational resources in regions where pitch changes are most significant, achieving high correction accuracy where needed while minimizing overall bit usage.
Solution Approach 2:
The patent segments the pitch correction process into multiple regions with different levels of precision. The time warping parameter table is divided into segments with varying numbers of pitch nodes, allowing the system to allocate coding bits efficiently - using more bits in segments requiring high precision and fewer bits in segments where coarse correction suffices.
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 2C~3(b)
AI summary
A coding device (10) includes: a pitch contour detection unit (101) which detects a pitch contour of an input audio signal; a dynamic time warping unit (102) which determines the number of pitch nodes based on the pitch contour and generates a first time warping parameter including information indicating the determined number of pitch nodes, a pitch change position, and a pitch change ratio; a first encoder (103) which codes the first time warping parameter; a time warping unit (104) which corrects pitch, using the information obtained from the first time warping parameter, to approximate the pitches of the number of pitch nodes to a predetermined reference value; a second encoder (105) which codes the input audio signal at the corrected pitch; and a multiplexer (106) which multiplexes the coded time warping parameter and the coded audio signal to generate a bitstream.