Circular Buffer Memory for Pre-Event Surveillance Recording
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Solution Overview
Problem
Existing surveillance cameras and devices are limited in their ability to record multiple events without overwriting or offloading data, particularly failing to capture lengthy portions of data streams before a trigger signal is activated.
Innovation Solution
A memory system that utilizes a circular buffer to store multiple data streams, allowing for the protection of recent segments without overwriting, with the capability to capture at least 1 to 20 minutes of image frames, and using multi-gigabit removable flash drives to store data in logically dis-contiguous portions, enabling the recording of events before and after a start signal without data loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If continuous recording is used to capture unexpected events, then the probability of capturing the event is improved, but the cost of equipment and storage increases significantly
Solution Approach 1:
The system pre-loads a circular buffer with recent video frames before a trigger event occurs. When triggered, the buffer already contains pre-event footage, eliminating the need for continuous long-term storage while ensuring event capture. This preliminary preparation allows the system to have event footage ready without maintaining large storage capacity throughout.
Solution Approach 2:
The storage system is segmented into a small circular buffer for recent footage and larger long-term storage. The circular buffer continuously overwrites old data, maintaining only the most recent frames. This segmentation allows the system to prioritize recent event capture while managing overall storage requirements efficiently.
2Quantity of substance
If a small looping memory is used to reduce storage costs, then the storage capacity is reduced, but the ability to store lengthy pre-start signal data is lost
Solution Approach 1:
The system dynamically adjusts the effective storage capacity based on whether a trigger event has occurred. During normal operation, the circular buffer continuously overwrites data. Upon trigger, the system dynamically protects the buffer contents from overwriting, effectively extending the retained pre-event duration without permanently increasing storage capacity. This dynamic behavior allows the same physical memory to serve different functional requirements.
3Quantity of substance
If the circular buffer continuously overwrites data to manage storage, then storage capacity is optimized, but data from multiple events cannot be preserved
Solution Approach 1:
The system uses trigger events themselves to control the protection state of the circular buffer. Each trigger automatically initiates buffer protection, preserving that event's data without requiring external intervention. This self-service mechanism allows multiple events to be automatically captured and preserved as they occur, with each trigger independently managing its own data retention.
Data Source
AI summary
A surveillance system uses a flash or other memory to store multiple data streams, each of which includes pre-start signal and post-start signal data. An area of the memory is preferably utilized as a circular buffer, in which a second data stream can be recorded without overwriting a first data stream. Buffers can have sufficient to capacity to capture up to an hour or more of image frames. All suitable methods and apparatus for initiating start and stop signals are contemplated, including for example using a button, toggle or other switch, a verbal or other human interface, and using motion, sound, light or other sensors. It is also contemplated that embodiments can include an interface for altering or otherwise designating a pre-signal size of the recently used segment. Cameras according to present invention can be mounted in any desired manner, including for example in camera boxes, on eyeglasses, and on automobiles or other vehicle.