Audio Signal Encoding Using Frequency-Domain Pitch Period Selection
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Solution Overview
Problem
Existing audio encoding techniques, such as TCX (transform coded excitation), do not efficiently account for variations in amplitude of frequency-domain sample strings based on periodicity, leading to decreased encoding efficiency when encoding sample strings with widely varying amplitudes together.
Innovation Solution
An encoding method that determines a frequency-domain pitch period by selecting from candidates including a converted interval and its integer multiples, using a frequency-domain pitch period code to identify the pitch period, allowing for efficient encoding and decoding of sample strings with small amplitude variations based on pitch periods in the frequency domain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If TCX encoding mode is used to encode DFT coefficients, then encoding can be performed at low bit rates, but encoding efficiency decreases when sample strings with widely varying amplitudes are encoded together
Solution Approach 1:
The patent divides the frequency-domain sample string into multiple segments based on amplitude characteristics. Samples are rearranged and segmented into groups with similar amplitude variations, allowing each segment to be encoded separately with optimized parameters, thereby improving overall encoding efficiency while maintaining low bit rate operation
Solution Approach 2:
The patent introduces dynamic adjustment of encoding parameters based on the amplitude characteristics of sample strings. The encoder adapts the encoding method and parameters according to the actual amplitude variations in different segments, transforming a static encoding process into a dynamic one that optimizes efficiency for each segment's specific characteristics
2Device complexity
If sample strings with widely varying amplitudes are encoded together using fixed encoding criteria, then processing is simplified, but encoding efficiency decreases
Solution Approach 1:
The patent segments the sample string into multiple amplitude-based groups, allowing different encoding criteria to be applied to each segment. This segmentation enables the system to handle varying amplitudes effectively without requiring overly complex processing, as each segment can be encoded with appropriate simplified rules
Solution Approach 2:
The patent applies different encoding criteria to different segments of the sample string based on their local amplitude characteristics. Each segment receives tailored encoding treatment appropriate to its specific amplitude variation pattern, improving efficiency without requiring complex global processing
3Measurement precision
If frequency-domain pitch period is determined by exhaustive search, then accuracy is improved, but computational complexity increases
Solution Approach 1:
The patent performs preliminary processing by converting the time-domain pitch period into a frequency-domain pitch period candidate using a fixed conversion relationship. This preliminary action narrows down the search space for pitch period detection, allowing accurate determination without exhaustive search through all possible periods, thereby reducing computational complexity while maintaining precision
Solution Approach 2:
The patent uses a simplified model or template of the expected pitch period pattern to guide the detection process. By copying the structural characteristics of pitch periods into the detection algorithm, the system can accurately identify pitch periods without requiring complex exhaustive analysis of all possible patterns
Data Source
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AI summary
A frequency-domain sample interval corresponding to a time-domain pitch period L corresponding to a time-domain pitch period code of an audio signal in a given time period is obtained as a converted interval T1, a frequency-domain pitch period T is chosen from among candidates including the converted interval T1 and integer multiples U × T1 of the converted interval T1, and a frequency-domain pitch period code indicating how many times the frequency-domain pitch period T is greater than the converted interval T1 is obtained. The frequency-domain pitch period code is output so that a decoding side can identify the frequency-domain pitch period T.