Audio Decoding Alignment for Sine Wave Start Position
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Solution Overview
Problem
When using a sine wave signal to predict high frequency components in audio decoding, the fixed frame length can lead to variance in the emergence start position of sine wave components, resulting in inaccurate reproduction and audible degradation, especially at low sampling rates where quantization noise becomes noticeable.
Innovation Solution
The solution involves adjusting the combination start position of the sine wave signal independently of the noise boundary position, allowing for a more accurate alignment during decoding, which is achieved by including information representing the time difference between the combination start position and the noise boundary position in the encoding stream.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the sine wave signal is combined at fixed positions (SBR frame start or noise boundary) in spectral band replication, then the decoding process is simple and efficient, but the emergence start position of sine wave components varies causing inaccurate reproduction and audible degradation
Solution Approach 1:
The patent changes the parameter of sine wave combination position from fixed positions (SBR frame start or noise boundary) to variable positions determined by actual sine wave detection. The combination start position is dynamically adjusted based on the detected emergence position of sine wave components in the high frequency signal, allowing accurate reproduction while maintaining decoding efficiency through parameter optimization.
2Device complexity
If the fixed frame length is used in spectral band replication, then the encoding and decoding structure is simple, but quantization noise becomes noticeable especially at low sampling rates
Solution Approach 1:
The patent introduces dynamic adjustment to the fixed frame length structure by allowing the sine wave combination position to vary within the frame based on actual signal characteristics. This dynamic positioning within the fixed frame structure reduces quantization noise by ensuring sine wave components are combined at their actual emergence positions rather than at fixed intervals, thereby improving audio quality without increasing overall system complexity.
3Measurement precision
If the sine wave combination position is independently adjusted from noise boundary position, then the alignment accuracy of sine wave components is improved, but the encoding complexity increases due to additional time difference information
Solution Approach 1:
The patent applies partial action by independently adjusting only the sine wave combination position parameter while keeping the noise boundary position unchanged. This selective adjustment improves sine wave alignment accuracy without requiring complete reconfiguration of the encoding system. The additional time difference information is encoded efficiently, adding minimal complexity while achieving significant improvement in audio reproduction quality.
Data Source
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AI summary
The present technology relates to a signal processing device, method, and program that may obtain audio at a higher audio quality when decoding an audio signal. An envelope information generating unit 24 generates envelope information representing an envelope form of high frequency components of an audio signal to be encoded. A sine wave information generating unit 26 extracts a sine wave signal from the high frequency components of the audio signal, and generates a sine wave information representing an emergence start position of the sine wave signal. An encoding stream generating unit 27 multiplexes the envelope information, the sine wave information, and low frequency components of the audio signal that have been encoded, and outputs an encoding stream obtained as the result. As a result, the high frequency components included in the sine wave signal may be predicted at a higher accuracy from the envelope information and the sine wave information at the receiving side of the encoding stream. The present invention may be applied to a signal processing device.