Hey all I have been experiencing this issue off and on while messing with video modes while trying to get things dialed in with my PC Monitor (Dell Trinitron D1626HT) at 720x400 in the AO486 core. While experimenting with various modes I notice some they caused the screen to shake really fast at this resolution. I tried to pinpoint which specific setting in the modeline was the culprit by testing a more common resolution at 640x480. After testing some mode lines I found the following results:
640,24,64,88,480,3,4,20,35000 (fast shaking)
640,56,56,80,480,1,3,25,36000 (fast shaking)
640,16,96,48,480,10,2,33,25175 (works without any issues)
640,16,64,80,480,3,4,13,23750 (slow wobble)
Can anyone decipher the results above to determine which specific setting has an effect on this jittering/wobbling thats going on? I need to get a non jittering resolution for 720x400 but so far everything I tested had this issue.
720x400 modes tested that had this issue:
720,36,72,108,400,1,3,42,35500
720,24,72,96,400,3,10,10,32750
720,48,32,80,400,3,10,6,31250
Jittering and wobbling with specific custom video modes
-
- Posts: 61
- Joined: Wed Jun 24, 2020 7:41 pm
- Location: Denver, CO
- Has thanked: 29 times
- Been thanked: 23 times
Re: Jittering and wobbling with specific custom video modes
Updating with a video of the issue. I am unable to find a modeline at 720x400 that doesn't exhibit this issue. The best one I've found is:
This has the least perceptible flickering/jitter. The 640x480 wobble affect is shown in the video just to illustrate the differences between the two.
Video of issue here
Code: Select all
video_mode=720,36,72,108,400,1,3,42,35500
Video of issue here
Code: Select all
720x400 modelines tested:
720 36 72 108 400 1 3 42 35500 (Least perceptible shaking)
720 24 72 96 400 3 10 10 32750
720 48 32 80 400 3 10 6 31250
720 24 64 88 400 3 10 6 22250 (Out of scan range)
720 24 72 96 400 1 3 17 32640 (Out of scan range)
720 32 144 32 540 10 7 11 39850
720 18 108 54 400 12 2 35 28320
720 28 48 102 400 1 4 45 28300
720 15 108 51 400 11 2 32 28322
1440 48 144 192 400 3 10 10 65500
1440 96 152 248 800 3 10 30 138500
Re: Jittering and wobbling with specific custom video modes
A couple questions:
Is this connected via analog i/o board vga or hdmi direct video to vga?
Do you have the ao486 OSD vsync setting set to 60hz or variable?
Is this connected via analog i/o board vga or hdmi direct video to vga?
Do you have the ao486 OSD vsync setting set to 60hz or variable?
-
- Posts: 61
- Joined: Wed Jun 24, 2020 7:41 pm
- Location: Denver, CO
- Has thanked: 29 times
- Been thanked: 23 times
Re: Jittering and wobbling with specific custom video modes
Its connected hdmi to vga. Vsync settings doesn't make a difference. I also tried multiple converters and multiple monitors. Shaking is present in both settings. I'm just using the modeline that has the least shaking for now as I can't figure what in the modeline or settings could be adjusted to fix the issue.