Microphone Catch-Up Buffer for Latency Reduction
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Solution Overview
Problem
Digital microphones using MEMS technology suffer from latency issues during real-time acoustic activity detection, leading to inefficiencies and user dissatisfaction, particularly in voice recognition tasks, due to the time delay in data processing and the need for buffers to manage this latency.
Innovation Solution
A system that utilizes a host processing device to stitch real-time PDM data from a first microphone with buffered PDM data, allowing the host to recover latency and synchronize the data streams, enabling the use of a second microphone without a buffer and reducing latency issues by processing the data streams in a way that creates a sequentially ordered output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a buffer is used to store audio data during acoustic activity detection, then the detection reliability is improved, but the latency increases and real-time data piles up
Solution Approach 1:
The patent segments the audio data processing into two distinct paths: a buffered path for reliable acoustic activity detection and a real-time path for low-latency data processing. The host processing device receives both buffered PDM data and real-time PDM data, processes them separately, and then stitches them together, allowing the system to maintain both reliability and reduced latency simultaneously
Solution Approach 2:
The buffer stores audio data in advance before acoustic activity detection is performed. This preliminary storage of buffered data allows the detection process to proceed reliably without introducing latency to the final output, as the buffered data is already prepared and can be stitched to real-time data immediately
2Reliability
If buffered PDM data is processed over a longer time interval, then the acoustic activity detection is more reliable, but the real-time processing speed decreases
Solution Approach 1:
The patent divides the processing into two separate time intervals: a first time interval for processing buffered PDM data (longer duration for reliability) and a second time interval for processing real-time PDM data (shorter duration for speed). By segmenting the processing timeline, the system can optimize each path independently without compromising the other
Solution Approach 2:
The host processing device dynamically adjusts the processing intervals based on the nature of the data being processed. Buffered data receives longer processing intervals for thorough analysis, while real-time data receives shorter intervals for rapid processing. This dynamic adjustment allows the system to maintain both reliability and processing speed
3Speed
If latency is reduced by removing the buffer, then the real-time processing speed improves, but the acoustic activity detection reliability decreases
Solution Approach 1:
The patent merges the buffered data path and the real-time data path at the host processing device. The host receives both buffered PDM data and real-time PDM data, processes them through different intervals, and then stitches them together to create a continuous output stream. This merging allows the system to benefit from both the reliability of buffered data and the speed of real-time data processing
Solution Approach 2:
The host processing device acts as an intermediary between the buffered data source and the real-time data source. It receives both data types, processes them appropriately according to their nature, and combines them into a unified output stream, thereby mediating between the conflicting requirements of reliability and speed
Data Source
AI summary
At a microphone, voice activity is detected in a data stream while simultaneously buffering audio data from the data stream to create buffered data. A signal is sent to a host indicating the positive detection of voice activity in the data stream. When an external clock signal is received from the host, the internal operation of the microphone is synchronized with the external clock signal. Buffered data stream is selectively sent through a first path, the first path including a buffer having a buffer delay time representing the time the first data stream takes to move through the buffer. The data stream is continuously sent through a second path as a real-time data stream, the second path not including the buffer, the real-time data stream beginning with the extended buffer data at a given instant in time. The buffered data stream and the real-time data stream are multiplexed onto a single data line and transmitting the multiplexed data stream to the host.