DSD Audio Volume Circuit Without PCM Conversion Delay
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Solution Overview
Problem
Native playback of DSD signals lacks volume control capabilities, which limits sound quality and introduces delays due to the need for PCM conversion.
Innovation Solution
An audio circuit with an N-bit shift register and a replacement circuit that substitutes (N-M) bits with a mute bit string having a 50% mark rate, allowing for volume control in the DSD native format without PCM conversion, using a pseudo-random bit sequence or inverted mute bit string to maintain sound quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If native playback is used to maintain high sound quality, then sound quality is improved, but volume control capability deteriorates
Solution Approach 1:
The patent segments the DSD signal processing into two independent parts: the high-quality native DSD playback path and the volume control path. The volume control is implemented by selectively muting specific bit positions in the DSD data stream using a gain control circuit, rather than converting the entire signal to PCM. This segmentation allows volume control to be applied to the DSD signal without compromising the overall sound quality of native playback.
Solution Approach 2:
The patent introduces a gain control circuit as an intermediary component between the DSD data input and the output. This intermediary processes the DSD data by selectively replacing bits with mute bits based on the desired volume level, enabling volume control without direct PCM conversion. The gain control circuit acts as a mediator that preserves the DSD format while implementing volume adjustment.
2Adaptability or versatility
If PCM conversion is performed to enable volume control, then volume control capability is improved, but processing delay and jitter susceptibility worsen
Solution Approach 1:
The patent extracts the volume control function from the PCM conversion process. Instead of converting DSD to PCM and then applying volume control, the invention extracts and implements volume control directly on the DSD signal using a gain control circuit that selectively mutes bits in the DSD data stream. This eliminates the time-consuming PCM conversion step while preserving volume control capability.
3Adaptability or versatility
If PCM conversion is performed to enable volume control, then volume control capability is improved, but power consumption and circuit complexity worsen
Solution Approach 1:
The patent inverts the conventional approach by not converting DSD to PCM, but instead applying volume control directly to the DSD signal. The gain control circuit inverts the traditional signal processing chain by operating on the DSD bits directly, replacing specific bits with mute bits based on the desired volume level. This inversion simplifies the circuit by eliminating the PCM conversion infrastructure while achieving the same volume control function.
Data Source
AI summary
The audio circuit has a volume circuit structured to process a DSD signal that contains DSD data and a DSD clock. The volume circuit has a first shift register and a replacement circuit. The first shift register holds N bits of the DSD data. The replacement circuit replaces (N−M) bits (0≤M≤N) corresponding to a gain set value, out of N bits stored in the first shift register, with a mute bit string having a mark rate of substantially 50%.