Audio Recording Sampling Strategy for Time-Stretched Playback Quality
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Solution Overview
Problem
Conventional audio recording devices that stretch the reproduction time period of audio data often result in a significant deterioration of audio quality, causing discomfort due to differences in audio quality between stretched and unstretched portions.
Innovation Solution
An audio recording device and method that utilize a sampling processing unit to generate high-resolution audio data at a higher sampling rate within a predetermined period and normal audio data at a standard rate outside this period, with a reproduction time period conversion unit to stretch the high-resolution audio data, while optionally using a selection unit to combine or switch between the two, and signal processing units for adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the reproduction time period of audio is lengthened by stretching, then the audio becomes easier to hear, but the audio quality deteriorates significantly
Solution Approach 1:
The patent divides the audio signal into multiple frequency bands (e.g., low-frequency band and high-frequency band) and processes each band separately. Different stretching methods or parameters are applied to different frequency ranges, allowing the system to maintain audio quality while achieving time period extension. This segmentation prevents the uniform quality degradation that occurs with traditional whole-signal stretching.
2Duration of action of moving object
If the reproduction time period is doubled, then the frequency decreases to 1/2 and pitch lowers by one octave, but this creates large quality differences between stretched and unstretched portions
Solution Approach 1:
The patent applies different processing qualities or parameters to different portions of the audio signal. Specifically, it uses frequency-band-dependent processing where low-frequency and high-frequency components are handled differently during stretching. This local differentiation maintains overall audio quality consistency while achieving the desired time period extension, preventing the abrupt quality transitions that occur with uniform stretching.
3Manufacturing precision
If audio is sampled at a higher sampling rate in a predetermined period, then high-resolution audio data is generated, but the device complexity increases
Solution Approach 1:
The patent implements dynamic sampling rate adjustment where the sampling rate is changed based on the predetermined period requirements. The system switches between different sampling rates (e.g., higher rate during the predetermined period, standard rate otherwise) to generate high-resolution audio data only when needed. This dynamic approach maintains audio resolution while managing device complexity through conditional rather than continuous high-rate sampling.
Data Source
AI summary
Deterioration in audio quality is inhibited in a device which records audio and stretches a reproduction time period. A sampling processing unit performs processing of sampling audio in a predetermined period at a sampling rate higher than a predetermined sampling rate to generate audio data as high-resolution audio data, and processing of sampling audio outside the predetermined period at the predetermined sampling rate to generate audio data as normal audio data. Also, a reproduction time conversion unit stretches the reproduction time period of the high-resolution audio data.