Digital Audio Reproduction Speed Adjustment with Frequency Emphasis
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Solution Overview
Problem
Existing digital information recording and reproducing apparatuses fail to maintain high sound quality during special playback speeds other than double speed, particularly struggling with content that features quick speaking, such as variety shows and dramas.
Innovation Solution
A digital recording and reproducing apparatus that adjusts the reproduction speed of a data stream based on offset time information, employs skip/repeat control, and corrects output levels to emphasize high-frequency components, adapting these methods according to the characteristics of the audio data for improved sound quality during various special playback speeds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If audio data is decoded at fixed intervals for special playback, then playback speed is controlled, but sound quality deteriorates due to output level discontinuities
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the output level of decoded audio frames based on the playback speed ratio. When playback speed changes, the system modifies the output level parameter to compensate for discontinuities, ensuring smooth audio transitions. This is achieved by calculating appropriate output levels according to the speed ratio and applying gain adjustments to maintain sound quality across different playback speeds.
2Speed
If one audio frame is decoded for every two audio frames for double speed playback, then playback speed is doubled, but sound quality deteriorates
Solution Approach 1:
For double speed playback, the system decodes one audio frame every two frames and applies parameter changes by adjusting the output level to compensate for the reduced frame rate. The output level is calculated based on the speed ratio (2.0 for double speed) to maintain adequate audio energy and smooth transitions, preventing sound quality deterioration despite the lower decoding frequency.
Solution Approach 2:
The patent implements dynamics by adaptively changing the decoding and output strategy based on the desired playback speed. For double speed playback, it dynamically adjusts to decode at half the normal rate while compensating through output level adjustments. This dynamic adaptation allows the system to optimize performance for different playback speed requirements while maintaining sound quality.
3Speed
If skip/repeat control is applied for special playback, then playback speed is adjusted, but audio output quality varies with content type
Solution Approach 1:
The system implements dynamics by adaptively adjusting skip/repeat control parameters based on content characteristics. For news content with slow speaking, it uses different skip/repeat intervals compared to variety shows and dramas with quick speaking. The playback speed ratio and output level corrections are dynamically adjusted according to detected content types, ensuring optimal audio quality across different content genres while maintaining the desired special playback speed.
Data Source
AI summary
High audibility output is realized when audio output is provided in special playback. In special playback with audio output, skip/repeat control is done so that decoding and outputting of the audio data is periodically repeated/skipped during part of one frame. The output level may be corrected so as to emphasize appropriate frequency components. This realizes good audio output. In addition, the skip/repeat control and output level correcting methods are changed according to characteristics of the audio data to be reproduced. Also, this realizes good audio output.