This knowledge base article discusses the event rate and how to control it. This is particularity beneficial for network connections less than 2.5GigE as it will reduce issues like image latency, data overflow on the link, and the camera disconnecting from ArenaView. This article applies to users who are using the Triton2 EVS camera with either Arena SDK or with Metavision Studio (via the HAL plugin).
Data rate and event rate
The data rate and the event rate are separate but loosely correlated measures.
- Event Rate: This indicates the number of events being captured by the camera, measured in megaevents per second (Mev/s).
- Data Rate: This refers to the volume of data being output by the camera to the PC, measured in megabytes per second (MB/s). A higher event rate often means a higher data rate, but the two rates are not exactly proportional—a single event can vary in size because each event can contain information on one or more pixels.
Depending on how dynamic the scene is, the number of events captured by the camera can change. However, the maximum event rate is limited by the data rate between the camera and PC as well as the processing capabilities of your host computer.
Tips for controlling event rate
The Triton2 EVS camera can connect to the host using 1GigE and 2.5GigE. Using 2.5GigE gives your system the greatest ability to handle events. If your camera is connected using 1GigE, you have the following options to maintain control over the event rate:
- Turn on Event Rate Control (ERC): This is the most straightforward method, and it allows you to limit the number of events that are captured by the camera. For a 1GigE connection, it is recommended to set ERC to 40Mev/s.
- Use other controls: You can also use the biases, filters, regions of interest (ROI), and the Anti-Flicker Control to reduce the event rate.
Host PC specifications
All event data is decoded and processed on the host PC. Therefore, PC specifications such as CPU and available memory will impact the maximum event rate and image latency. Dynamic scenes with high levels of event data streamed to the PC will require more CPU processing power and memory.
EVS cameras and ArenaView
The “Disable device enumeration” setting in ArenaView affects the computer’s behavior when the host computer is processing an excessively large number of events.
The settings page in ArenaView.
| Disable device enumeration | Host behavior when it is overloaded with events |
| True | The camera will always be connected because the enumeration loop is halted. However, while the host is trying to process the overflow of events, the camera stream appears to freeze on ArenaView. The stream will continue once host has caught up with processing events. |
| False | The camera will drop the connection when the host is occupied with too many events since the camera’s enumeration loop is enabled and heartbeat will timeout when the host is too busy. |