FCAT Frametime analysis
Frametime and latency performance
With FCAT we will look into Frame Experience Analysis. Basically with the charts shown we are trying to show you graphics anomalies like stutters and glitches in a plotted chart. Lately there has been a new measurement introduced, latency measurements. Basically it is the opposite of FPS.
- FPS mostly measures performance, the number of frames rendered per passing second.
- Frametime AKA Frame Experience recordings mostly measures and exposes anomalies - here we look at how long it takes to render one frame. Measure that chronologically and you can see anomalies like peaks and dips in a plotted chart, indicating something could be off.
| Frame time in milliseconds |
FPS |
| 8.3 | 120 |
| 15 | 66 |
| 20 | 50 |
| 25 | 40 |
| 30 | 33 |
| 50 | 20 |
| 70 | 14 |
We have a detailed article (read here) on the new FCAT methodology used, and it also explains why we do not use FRAPS anymore. Frametime - Basically the time it takes to render one frame can be monitored and tagged with a number, this is latency. One frame can take say 17 ms. Higher latency can indicate a slow framerate, and weird latency spikes indicate a stutter, jitter, twitches; basically anomalies that are visible on your monitor.
What Do These Measurements Show?
What these measurements show are anomalies like small glitches and stutters that you can sometimes (and please do read that well, sometimes) see on screen. Below I'd like to run through a couple of titles with you. Bear in mind that Average FPS often matters more than frametime measurements.
Above, the percentile chart of a 31 second recording @ 2560x1440. Here we plot FPS and place it in relation to percentiles. 50% of the time measured frames is the average framerate (higher = better).
Aside from a but of rough start of the lap (racing game) we cannot see a significant enough glitch or stutter in frame-time scaling (chart wise) that is significant or long-lasting.
With this chart, lower = better. Huge spikes above 40 ms to 50 ms can be considered a problem like a stutter or indicate a low framerate. It's all good here.
And combined, the cards both perform really well and very similar towards each other. Nice.
