Main Restorations Software Audio/Jukebox/MP3 Everything Else Buy/Sell/Trade
Project Announcements Monitor/Video GroovyMAME Merit/JVL Touchscreen Meet Up Retail Vendors
Driving & Racing Woodworking Software Support Forums Consoles Project Arcade Reviews
Automated Projects Artwork Frontend Support Forums Pinball Forum Discussion Old Boards
Raspberry Pi & Dev Board controls.dat Linux Miscellaneous Arcade Wiki Discussion Old Archives
Site News

Unread posts | New Replies | Recent posts | Rules | Chatroom | Wiki | File Repository | RSS | Submit news


  

Author Topic: LCD lag testing and ideas for improvement  (Read 698 times)

0 Members and 1 Guest are viewing this topic.

jimmer

  • Trade Count: (0)
  • Full Member
  • ***
  • Offline Offline
  • Posts: 506
  • I want to play Defender like at the arcade.
LCD lag testing and ideas for improvement
« on: May 10, 2018, 06:28:50 pm »

The zipped movie shows some lag testing.  Dell1913 TN panel, framedelay 9, filmed on LGv10 at 120fps, arduino keyboard encoder lights up the red LEDs when fire is pressed (and yellow for up or down). Note: the LEDs appear across more frames than they should (programmed for 17ms) that may be persistence in the CCD? or maybe the switch off is slow.   

I count the response in video frames (= 8.3ms) from 0 when the LED comes on to N when the laser shot appears. Typically I get values of 3,4,5,6 which is in line with what I was expecting and it caused me to assume a value of about 10ms for the lag in the LCD (signal processing +pixel response).

However I got a frame 2 response (at 0.82s in the video) and the only way I can explain that is by cutting my assumed display lag to about 5ms.

Attached is my theoretical explanation diagram.



Assuming my understanding is correct, I'd expect better response at the top of the screen (I'm pretty sure the LCD is lit from top to bottom) but I get about 1 frame count worse on average. I've got a slight suspicion that there could be something dicky with the emulation so that the top action drops into the next frame of output (Defender pcb polls every 8.3ms) but I can't guess why yet, that's work for later.


Any comments?  or anyone else interested in LCD performance ?

I've got dreams of chopping 16ms off the average time; 8ms via emulation change (8ms polling), and 8ms via 120fps display.
On forums jimmer speaks for himself as a Defender fan, not as proprietor of www.jbgaming.co.uk  << Is that advertising or disclosure ? or both ?

oomek

  • Trade Count: (0)
  • Full Member
  • ***
  • Offline Offline
  • Posts: 132
  • Mame forever.
Re: LCD lag testing and ideas for improvement
« Reply #1 on: May 13, 2018, 11:51:54 am »
I get min. 5ms overall latency on a Samsung 27SF350 with Freesync enabled and all sync related functions off in GM, throttle on. Personally I think that using other syncing methods on an lcd is counterintuitive in my opinion as Freesync gives the best results. Lag recorded using 1200fps camera
« Last Edit: May 13, 2018, 11:53:57 am by oomek »

RobertJ

  • Trade Count: (0)
  • Full Member
  • ***
  • Offline Offline
  • Posts: 87
Re: LCD lag testing and ideas for improvement
« Reply #2 on: May 14, 2018, 02:58:15 am »
I'm guessing nobody makes a nice large freesync 4:3 LCD monitor? :(

Calamity

  • Moderator
  • Trade Count: (0)
  • Full Member
  • *****
  • Offline Offline
  • Posts: 6027
Re: LCD lag testing and ideas for improvement
« Reply #3 on: May 14, 2018, 12:13:46 pm »
Give me some time to digest your graphics and I'll post something.
Important note: posts reporting GM issues without a log will be IGNORED.
Steps to create a log:
 - From command line, run: groovymame.exe -v romname >romname.txt
 - Attach resulting romname.txt file to your post, instead or pasting it.

CRT Emudriver, VMMaker & Arcade OSD downloads, documentation and discussion:  Eiusdemmodi

oomek

  • Trade Count: (0)
  • Full Member
  • ***
  • Offline Offline
  • Posts: 132
  • Mame forever.
Re: LCD lag testing and ideas for improvement
« Reply #4 on: May 14, 2018, 01:51:28 pm »
Drawing time on the LCD takes exactly the same time as the frame time for a specific framerate.
So always measure the top side of the screen. I donít know about Defenderís polling rate and frame buffering, but I can link my Thunder Cross rom with modified number tiles to be white squares, which I use. This game definitely has no internal buffering on the test screen and it was giving me very consistent results.

jimmer

  • Trade Count: (0)
  • Full Member
  • ***
  • Offline Offline
  • Posts: 506
  • I want to play Defender like at the arcade.
Re: LCD lag testing and ideas for improvement
« Reply #5 on: May 14, 2018, 04:16:30 pm »
That diagram with all the circles (LEDs) might be a bit over the top !

This is the sort of thing I was thinking I might be able to achieve with a 120fps display?  All I really want is the quicker rendering to screen, it doesn't need the black frame. Maybe frame doubling is better. It's all getting very confusing now!

It almost seems like it might be easier to do a custom emulator that polls every 8ms and writes ahead of the 'beam'.  Is that possible with LCD or is there something that stops you writing ahead of the display in the current frame? 

« Last Edit: May 14, 2018, 04:37:05 pm by jimmer »
On forums jimmer speaks for himself as a Defender fan, not as proprietor of www.jbgaming.co.uk  << Is that advertising or disclosure ? or both ?

jimmer

  • Trade Count: (0)
  • Full Member
  • ***
  • Offline Offline
  • Posts: 506
  • I want to play Defender like at the arcade.
Re: LCD lag testing and ideas for improvement
« Reply #6 on: May 14, 2018, 05:22:38 pm »
I get min. 5ms overall latency on a Samsung 27SF350 with Freesync enabled and all sync related functions off in GM, throttle on. Personally I think that using other syncing methods on an lcd is counterintuitive in my opinion as Freesync gives the best results. Lag recorded using 1200fps camera

5ms is good. I've found your video.

Is the LED wired to the button or is it switched on with arduino code?  I switch mine with code, but I haven't tested for any delay (which would give better results than deserved)
 
On forums jimmer speaks for himself as a Defender fan, not as proprietor of www.jbgaming.co.uk  << Is that advertising or disclosure ? or both ?

oomek

  • Trade Count: (0)
  • Full Member
  • ***
  • Offline Offline
  • Posts: 132
  • Mame forever.
Re: LCD lag testing and ideas for improvement
« Reply #7 on: May 14, 2018, 06:05:33 pm »
Iíve had an arduino before, but now Iím just using a simple circuit consisting of an led, transistor and a resistor which is wired to one of the buttons.

Paradroid

  • Trade Count: (0)
  • Full Member
  • ***
  • Offline Offline
  • Posts: 548
    • SCART Hunter
Re: LCD lag testing and ideas for improvement
« Reply #8 on: May 14, 2018, 09:28:22 pm »
Iím just using a simple circuit consisting of an led, transistor and a resistor which is wired to one of the buttons.

Keen to see how to wire this up... also keen to know more about that crazy fast camera you mentioned.
My MAME/SCART/CRT blog: SCART Hunter

oomek

  • Trade Count: (0)
  • Full Member
  • ***
  • Offline Offline
  • Posts: 132
  • Mame forever.
Re: LCD lag testing and ideas for improvement
« Reply #9 on: May 14, 2018, 09:41:37 pm »
Iíll draw a circuit tomorrow. The camera Iím using is Nikon V1. The quality is pretty ---steaming pile of meadow muffin--- at 1200fps, but I bought it only for measuring the lag.

Ps. Thank you forum fairy for transcribing my words
« Last Edit: May 14, 2018, 09:45:52 pm by oomek »

  
 

Sitemap 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31