piLagTesterPRO and the raspberry pi4: an alpha release is available

The piLagTesterPRO is a tool to measure display input lag, using custom hardware plugged into a raspberry pi. It works great on the pi 0, a $5 computer that out-specs SGIs from the mid-90s. It also works great on higher end PIs, such as the Pi3, which has a much faster processor but the same GPU as the pi0. 

**** UPDATE: full Pi4 is now available, the text below is out of date *****

It's now available for the pi4 too! but first some background:

The raspberry pi4 has been a problem because it uses a new GPU with much better specs but no backwards compatibility. For a while I've been working on supporting it. While it kind of worked, it wasn't ready for prime time, but now the official firmware and my work-around for bugs in the firmware seem to have reached a threshold where it would be reasonable to make a testing release.

While it works well for me I don't have the equipment to test the higher resolutions and refresh rates that the PI4 offers. Since this is the reason for using the Pi4 in the first place, I'm hesitant to call this a beta. Instead it's an alpha. This is not out of undo caution (I think). The Pi4 firmware has a bug where moderately high demands on the CPU cause the GPU to drop frames and it's very difficult to detect this in software, AND still know what the right value is.  From an end user perspective it's easy to tell something's up though: input lag will suddenly change by 16ms. I think I've got the code optimized enough to avoid this issue but there is a chance it will occur for higher refresh rates or resolutions. 

That's why I need your help. I need folks to test this on a range of displays and see if the input lag values stay constant or start to jump up/down by exactly 16ms. So for those of you who already own the piLagTesterPro and have a pi4, please try this image on your pi4. if you have an earlier pi, there's no reason to try this image. 

here's the download link; please don't use unless you have a pi4 and a piLagTesterPRO as it will eventually use up my quotas:

 https://1drv.ms/f/s!Ahb4rgU6L_z9gxV287CTdwmz8mvh

currently requires a 16gb microsd card, write it as you would any raspbery pi OS image.

login as root, password = t (just the letter t). you will see instructions after you log in.





Comments

Post a Comment

Email me

Name

Email *

Message *

Popular posts from this blog

Panasonic TH-42PX75U Plasma TV review: input lag and upscaling tested using the piLagTesterPRO

Image
This 720p Plasma TV from 2008 is very unique and quite nice in many ways. It used to retail for around $1300. If you can find one it's a great choice for retro gaming.  Overview/Image quality This is a plasma TV, which generally means at least the following: nearly infinite viewing angles, and jaw dropping weight. That's true in this case as well. This 42" model weights 75lbs.  At native resolution (720p) this TV crops 20 pixels off the top/bottom and 30 off the sides. 480p/i crops 20 pixels off all sides. Both modes have aliasing, too, though it's not too bad. There's really no excuse for aliasing on a TV this big: you know the panel was designed specifically to be a tv. Why not hit 720p exactly? And as for 480p/i, they could have at least offered a zoomed out mode with black borders and 1:1 pixel mapping. But no such luck. There are zoom/stretch options to crop even more, but none that crop less. While the native resolution supposedly is 1366 x 768 it does accept
Read more

piLagTester PRO order page

Image
The piLagTesterPRO measures your monitor's input lag and response time. It is a cheap, full featured add-on to the Raspberry Pi; I provide the sensor and required software, you provide the Pi (a $5 pi Zero is more than sufficient). Although it has a DIY aesthetic, it is quite functional and in fact offers quite a lot more features than the commercial alternatives (Leo Bodnar and the Time Sleuth), and has been tested with over 40 TVs, including 4k models .  Here's what it looks like in action: The pi draws a black background, and then roughly once a second displays a set of target rectangles (top/middle/bottom). You place the sensor over the desired target, and the piLagTester measures the monitor's response starting from the moment the frame of video data is sent over the Pi's HDMI port. This is plotted in the graph, which is sideways for space reasons. The lag tester measures two thresholds. In red it shows how long it takes for the monitor to start displaying t
Read more

A $5 TV Input Lag tester using a Raspberry Pi Zero

Image
High speed monitors are all the rage now, with quoted response times  of 1-4ms. But does that mean that 1-4ms after you make an input (say, jump) you will see that on your screen? No. Often a much bigger issue is  Input lag. This is   the delay between your computer / game console sending a video frame to your display and your display starting to actually show it, and it ranges from 4ms to 80ms. The problem with measuring input lag is that you can't, at least with everyday hardware. The solution for hardware review sites is to purchase dedicated lag testers such as the leo bodnar tester,  timesleuth (both ~$100), or the pi lag tester pro ($40) or use homegrown methods utilizing an oscilloscope ("free" if you already own a $400+ oscilloscope and perhaps a $50k+ engineering degree). Here I introduce a $5 solution (or, "free" if you own the required equipment). What's required: A Raspberry Pi Zero ($5 + S&H from several sources). This single board c
Read more