I thought I'd tag onto this thread since it's fairly similar.
I recently bought a Slimport VGA adapter in the hope I could output my phone's screen to my car's display panel.
My car (Japanese import) has a navigation computer which is useless in Australia. So instead of having a useless screen molded into my dash I wanted to use my phone as essentially a CarPC. Now the neat thing is the Navigation computer connects to the display panel via RGBHV, essentially VGA.
So I made a custom cable to go from the car's display panel to a HD15 VGA plug, plugged the Slimport VGA adapter in and it worked! My phone's video output was placed on the car's display panel. But obviously very down scaled.
I figured out that my car uses 800x480 WVGA (Wide VGA) across its 7" 5:3 panel and started messing around in Terminal Emulator to change the phone's screen size with;
wm size 480x800
wm density 240
Which strangely resulted in the video being letter boxed; Big black bars top and bottom. I then tried a bunch of other standard resolutions and found that 4:3 resolutions filled the screen vertically, but were being cropped on the left and right. And 5:4 resolutions filled the screen completely, however were being stretched horizontally.
I was not able to match the native resolution of the car's display panel or have the correct aspect ratio.
Frustrated I plugged the Slimport VGA adapter into my computer monitor and it all became clear; no matter what resolution you set the phone to; the *ONLY* resolution coming out of the Slimport VGA adapter is 1280x1024 (a 5:4 aspect resolution) with whatever selection you have made with the wm size commands being stretched or scaled across this.
Which is why selecting a 5:3 resolution had black bars top and bottom inside the 5:4. And 4:3 was being cropped on the left and right. And of course a 5:4 resolution filled the screen but was stretched and not 1:1 / native.
Now my question is:
Has anyone else come across this before and found a work around or fix? Are there other Slimport adapters that have been *confirmed* to output different resolutions and not just simply scale to one fixed output size?
For reference: I have a rooted LG G3 D855 32gb and am running a fairly recent CM12.1 (Lollipop 5.1.1) nightly.
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