HDMI Splitter

Has anyone had experience of HDMI splitters?

The HDMI output from my Raspberry Pi feeds into a Cablesson HDelity 1×2 HDMI Deep Colour full 3D splitter. The outputs go to a widescreen 1920 × 1080 monitor (V2410 Eco) and a BenQ MP525ST Digital Projector (1024 × 768).

The monitor displays an extremely compressed image in the vertical direction, leaving large black areas at the top and bottom of the screen making it unusable in this setup. This doesn’t seem as noticable on the digital projector perhaps because of its lower resolution.

Is there a way of altering the configuration in the Boot loader to counteract this effect. I’ve tried various parameters in the CONFIG/TXT file but to no avail. It’s looking increasingly likely that the splitter is not compatible?

Sounds like it is using the EDID info from the widescreen monitor and ignoring your setting in config.txt.
To get the best results you will have to set the Pi’s GPU to output the native resolution of the projector in the config.txt file. Also use the same resolution mode within RISC OS.
To see that your setting in config.txt are working set it to say 800×600 or 640×480 then try 1024×768.

I suggest posting here your complete config.txt

I expect to be too busy to respond myself before next week.

Another idea: Unplug the monitor’s data lead and power everything up. i.e. Pi → Splitter → Projector
or even Pi → Projector

Connecting only the monitor to the splitter I got a full screen 1920 × 1080 image – hooray! When I connected the digital projector it also produced a satisfactory image. So perhaps it is wise to power projector last. Further tests are required to confirm.

Incidentally the command… hdmi_ignore_edid=0xa5000080 which ignores monitors EDID info. seems to make no difference.

Thanks Chris for your ideas and good luck with the show.

I think I may have solved my problem.

The switch-on procedure must be precisely observed to ensure a full-screen image on the monitor. I doubt many of you give presentations but I’ll post it if anyone needs it.