Latency
Display latency measures the time it takes for a new video frame to appear on the screen after it's been received. It's usually expressed in frames or milliseconds.
Low latency is critical in applications demanding real-time feedback because it minimizes the delay between an action and its visual representation on the display.
This has several important implications:
Live Events: For concerts, sports broadcasts, and other live events, low latency ensures that the audience sees the action unfold on the screen almost instantly, enhancing their sense of immersion and engagement.
Gaming: In fast-paced games, split-second reactions can be the difference between winning and losing. Low latency minimizes the delay between a player's input and the corresponding action on screen, providing a more responsive and competitive experience.
Virtual Production: Virtual production relies on real-time interaction between actors, cameras, and the virtual environment displayed on LED walls. Low latency is essential to maintain the illusion of presence and avoid any jarring disconnects between the physical and virtual worlds.
Understanding latency
It's important to note that manufacturers might define latency differently:
Some measure from the start of receiving the new frame via the video cable
Others measure from the end of receiving the full frame.
With standard video inputs like HDMI or SDI, a full frame's worth of time is needed for complete transmission. So, latency measured from the start will always be one frame longer than latency measured from the end.
Measuring latency
For standard latency measurements, Deepsky utilizes a commercial device that sends at 60 images per second (60fps) to the display via HDMI. This device tracks the total time it takes for a video frame to travel from the start of its transfer to the LED processor, all the way to when it's actually visible on the screen.
It's important to understand that at 60fps, each frame takes about 16.67 milliseconds (1/60th of a second) to transfer through the HDMI cable itself.
So, if the total measured latency is 22.8ms, this means:
16.67ms is due to the inherent transfer time within the HDMI cable
The remaining 6.13ms represents the actual latency introduced by the Deepsky display control system (from processor to LED driver).