DSD Signal Switching by Pre-Interpolation Across Sampling Rates
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Solution Overview
Problem
Existing methods for switching between DSD signals with different sampling frequencies, such as those described in PTL 1, require conversion to PCM signals and crossfading, which are burdensome for embedded CPUs and result in signal processing delays, and cannot handle delta-sigma modulated signals directly.
Innovation Solution
A signal processing apparatus and method that includes an acquisition section and an interpolation section, which acquires and pre-interpolates digital audio signals to match the sampling frequency with the operating clock of a delta-sigma demodulator, allowing direct switching between DSD signals without conversion to PCM.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conversion to PCM signal and crossfading is performed for switching between DSD signals, then switching between different sampling frequencies is achieved, but processing burden increases and delays occur
Solution Approach 1:
The invention extracts only the necessary interpolation operation from the complex PCM conversion and crossfading process. By keeping the DSD signal in its delta-sigma modulated form and applying only pre-interpolation to adjust sampling frequency, the solution removes unnecessary conversion steps while maintaining switching capability between different DSD sampling frequencies (64DSD, 128DSD, 256DSD).
Solution Approach 2:
The invention performs pre-interpolation on the DSD signal before delta-sigma demodulation to adjust the sampling frequency to match the operating clock. This preliminary adjustment eliminates the need for complex real-time conversion and crossfading operations during playback, reducing processing burden and delays while enabling smooth switching between different sampling frequencies.
2Adaptability or versatility
If PCM conversion and crossfading are used for DSD signal switching, then switching is achieved, but processing time increases due to burdensome operations
Solution Approach 1:
The invention extracts only the essential pre-interpolation step from the complex PCM conversion and crossfading process. By maintaining the DSD signal in its native delta-sigma modulated form and applying only sampling frequency adjustment through pre-interpolation, the solution eliminates time-consuming conversion operations while preserving switching capability between different DSD sampling frequencies.
Solution Approach 2:
The invention uses pre-interpolation to create a time-stretched or time-compressed version of the DSD signal that matches the target sampling frequency. This copying approach with temporal adjustment allows direct switching between different DSD signals without requiring complex real-time conversion and crossfading operations, thereby reducing processing delays.
3Adaptability or versatility
If complex conversion processes are applied to DSD signals, then switching between sampling frequencies is possible, but the configuration becomes complicated
Solution Approach 1:
The invention extracts only the necessary pre-interpolation function from the complex chain of PCM conversion, crossfading, and delta-sigma modulation. By keeping the DSD signal in its native form and applying only sampling frequency adjustment through pre-interpolation before demodulation, the solution achieves multi-frequency signal handling with a simplified configuration that requires fewer processing stages.
Solution Approach 2:
The invention performs pre-interpolation in advance to adjust the sampling frequency of the DSD signal to match the operating clock of the delta-sigma demodulator. This preliminary frequency adjustment eliminates the need for complex real-time conversion configurations during signal switching, thereby simplifying the overall system configuration while maintaining adaptability to different sampling frequencies.
Data Source
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AI summary
The present technology relates to a signal processing apparatus, a signal processing method, and a program that permit switching between a plurality of DSD signals having different sampling frequencies using a simple configuration. An acquisition section acquires a digital audio signal having a given sampling frequency selected from among the plurality of digital audio signals acquired by delta-sigma modulating an audio signal at a plurality of sampling frequencies. An interpolation section subjects the acquired digital audio signal to a pre-interpolation process when the sampling frequency of the acquired digital audio signal is lower than an operating clock of a delta-sigma demodulator. The present technology is applicable, for example, to a signal processing apparatus.