Before measuring input lag, you should have a basic understanding of the difference between video latency and input lag.
- Measuring input lag allows direct comparison to existing reviews that use this measurement method.
- Measuring video latency has advantages such as its use in calculating lip sync error.
Using the Leo Bodnar Tester
Input lag can be measured using a Leo Bodnar video signal lag tester for the following HDMI video formats:
| 3840x2160p 60.00Hz | 1920x1080p 60.00Hz | 1280x720p 60.00Hz |
| 3840x2160p 50.00Hz | 1920x1080p 50.00Hz | 1280x720p 50.00Hz |
| 3840x2160p 30.00Hz | 1920x1080p 30.00Hz | |
| 3840x2160p 25.00Hz | 1920x1080p 25.00Hz | |
| 3840x2160p 24.00Hz | 1920x1080p 24.00Hz |
Steps
- If you’re using the 4K tester, make sure that its firmware is up to date.
- Follow the setup instructions and usage guidelines provided by Leo Bodnar.
- Record the reported lag value at the center of the middle white block. This is the input lag.
The Leo Bodnar testers report the time between when the first active pixel leaves the FPGA and when its sensor detects the display has reached approximately 6% of full luminance. The tester outputs an HDMI signal with CEA timings.
Some earlier firmware versions of the fixed-resolution testers measured from the start of blanking rather than the first pixel. This was changed with later versions of the firmware to match the behaviour described in the previous paragraph.
Last updated on October 8th, 2021.