Pixel aspect ratio for 7'' display

[Romanz]

Good afternoon.
So it turns out that this monitor cannot be brought to a resolution of 1024*600? So now it’s not software for hardware, but hardware for software? Interestingly, the latest version of Volumio works correctly with this screen.

This type of screen

[the_bertrum]

The challenge is that many display manufacturers in the DIY space don't keep up and test with new OS releases. I wouldn't count on much support from them for any given panel.

Although this also seems to apply to the "official" 7" screen as well right now

[Romanz]

It turns out that this is a problem for all 7" screens on moode 9.x.x?

[TheOldPresbyope]

@Romanz 

Interestingly, the latest version of Volumio works correctly with this screen.

I know this observation was well meaning but such statements are generally not useful. At the very least, one needs to know details such as what version of the Raspberry Pi OS is it built on (e.g., bullseye, buster, bookworm)? What version of the Linux kernel? We're not Volumio devs and most of us aren't Volumio users.

I'm willing to bet a coffee that they're still building on bullseye.

Regards,
Kent

[TheOldPresbyope]

Regarding Tim's last post, I wouldn't count on *any* support.

When a DIY LCD panel hides behind an HDMI interface one has a reasonable expectation that it will behave according to HDMI standards.

My experience is "good luck with that". The little 3.5-in panel I pulled out of my tinker's box appears to have a physical resolution of 480x320 pixels but the HDMI interface advertises (via EDID) that it can run at 44 different resolutions including 480x320 and all the way up to 1920x1080. Not on your life. 

Regards,
Kent  

PS - I said "appears to" because that's the only number I've been able to find in "documentation". I haven't successfully proven to myself that it's the actual panel pixel count.

[the_bertrum]

Seems we have run into the reason why hardware manufacturers eventually stop offering software updates. If moOde were a physical box that shipped with a screen, then v8 devices would now just stop getting updates and anyone wanting v9 would have to buy a new box. Hopefully Pi OS will get an update that fixes non-square pixels at least, even if they can't do anything about panels that claim resolutions they can't display.

[Tim Curtis]

Here's a summary of some quick tests I ran this morning with my two screens. As you can see the only issue is "non-square pixels" on the 7" Touch, otherwise the screens worked fine.

Pi Touch 7" + Pi-3B

Code:

=========================
Pi Touch 7" + Pi-3B
A/R: 5:3 or 1.67:1
Interface: DSI
Issues: Non-square pixels
=========================
# Viewport
moodeutl -q "update cfg_system set value='viewport' where param='pkgid_suffix'"
Then Menu, Refresh
799x479

# Resolution
pi@moode9test:~ $ kmsprint | awk '$1 == "FB" {print $3}' | awk -F"x" '{print $1","$2}'
800,480

# Config.txt
No custom settings

# Integrated audio (System Config)
Kernel mode (Default)
This leaves dtoverlay=vc4-kms-v3d uncommented in config.txt

WIMAXIT 10.1" + Pi-4B

Code:

=========================
WIMAXIT 10.1" + Pi-4B
A/R: 16:9 or 1.78:1
Interface: HDMI
Issues: None
=========================
# Viewport
moodeutl -q "update cfg_system set value='viewport' where param='pkgid_suffix'"
Then Menu, Refresh
1599x899

# Resolution
pi@moode9test:~ $ kmsprint | awk '$1 == "FB" {print $3}' | awk -F"x" '{print $1","$2}'
1600,900

# Config.txt
No custom settings

# Integrated audio (System Config)
Kernel mode (Default)
This leaves dtoverlay=vc4-kms-v3d uncommented in config.txt

You can use these same commands to try and debug screen issues having to do with viewport size or resolution.

The "non-square pixels" issue on the old Bullseye OS was fixed by the config.txt settings below. These settings on Bookworm don't work with its default vc4-kms-v3d videocore driver. IIRC this driver is configured by dtoverlays and not individual frame buffer settings like below.

Bullseye settings that fix non-square pixel issue on Pi 7" Touch

Code:

framebuffer_width=800
framebuffer_height=444
framebuffer_aspect=-1

Btw I also have a couple Samsung 7 series 4K TV's, an old ASUS 24" monitor (1366x768) and an old Westinghouse 32" HDTV (1366x768) that all work perfectly with moode9.

Basically if some screen doesn't work correctly with moode9 then either the manufacturer or users have to provide a solution that can be investigated.

[TheOldPresbyope]

I left unsaid that moOde’s local display feature “works” with my 3.5-in LCD panel without any customization of moOde configuration—the screen is filled and looks almost correct—but the aspect ratio of the displayed image is wrong (the subject of this thread, after all). What should be circles are slightly stretched vertically; same with square cover art. The distortion is just enough to be annoying. RaspiOS and moOde think the display is 1280x720.

For want of a better explanation, I’ll blame the distortion on non-square pixels. To borrow your words, I’m investigating.

Regards,
Kent