Hi…here is an issue I wasn’t expecting. My VSERPI prototype is up and running and uses an HDMI video splitter to display on a small touch display and the main output. While testing I’ve been using my desktop monitor as HDMI display, but the intention as always been to use a Xaomi portable cube projector on stage. BUT when I hook the extra HDMI out from the VSERPI to the HDMI input of the projector…nothing!
I’ve tested the projector input with my MacBook M1 and a Chromecast w/ Google TV and both are recognized without issue.
So I’m wondering - what is a likely cause of this and what might be a way around it? The VSERPI and the projector are usually at different locations, but I can do some more troubleshooting at some point this week…
Does the Pi’s HDMI signal still not show up when using a direct connection (no splitter) to the projector? If so, I’d suggest trying to confirm the specs of the Xiaomi projector and checking if there may be a minimum required resolution through its HDMI ports for it to work correctly. Important to remember that even though VSERPI can output video via HDMI, technically the resolution is still 480p (SD), so it’s possible that the projector simply isn’t recognizing it for that reason.
You could probably test this on your projector if you have an older (I’d reckon like early-to-late-00’s) video device such as a DVD player with an HDMI output that doesn’t upscale the image to HD res (720p or higher). If the projector doesn’t want to play nice with that in a similar way as the Pi 3B+, then that’s probably what you’re dealing with.
For a quick fix, I’d recommend using the Pi 3B’s composite video out instead of HDMI if your projector has an A/V input. For a real fix, I’d look into adding an upscaler to the end of your chain to bump the signal into actual HD resolutions that the projector would typically expect from an ordinary HDMI input.
EDIT: I think a Sony PS3 would also be a good device to use for troubleshooting this, since you can adjust the HDMI output resolution anywhere from 480 to 1080 easily in the settings.
Thanks, these are great suggestions and I’ll investigate during the week. I’m also curious about my HDMI splitter. On Amazon it was listed as HDMI 2.0 but the accompanying booklet states HDMI 1.4b. It supports, apparently, full 3D and HDMI resolution up 3840x2160@30Hz. It also lists “Displaying single source, multi-output high-definition signal source from DVD player, A/V receiver, settop box” although I suspect it’s a bit misleading. Probably anything going in as SD comes out as such. Well, I’ll see I suppose…!
Might be a bit of a convoluted solution, but for a cheap(er than fancy HDMI peripherals) workaround you could simply try a dinky RCA->HDMI converter/upscaler box to adapt the Pi’s composite out to 1080p HDMI and see if that works for you. Definitely want to be mindful that it actually features the ability to upscale and doesn’t just provide a pass thru of the original 240p image. These devices usually don’t produce the best looking result, but it is perfectly functional and virtually zero fuss to get working.
Alternatively for a better looking image, if your live setup is amenable to incorporating your Mac you could use a cheap HDMI to USB-C capture dongle to receive the Pi’s 480p HDMI signal, then use video software like OBS/VLC/Quicktime/etc to display and/or upscale the image fullscreen. Then the Mac could just HDMI out to the projector at its native resolution, and you’d have the Macbook’s display in front of you to serve as a larger preview monitor, removing the need for a splitter. Might have to deal with some noticeable latency between the source (pi) and the final image via this process though, so that may or may not be a big deal for you depending on your particular viz biz.
The ideal solution for this setup imo would be to have a dedicated SD/HD video mixer with built-in upscaling at the end of your chain, something that’s designed to work with both analog and HD connections/resolutions and will always output a solid signal via the main HDMI out. The Roland V-4EX or VR-3EX are both examples of such devices that have been lifesavers for me more times than I can count in scenarios exactly like this, and have many more very handy utility features that have helped me through loads of other jams when troubleshooting and setting up for live shows. Expensive tools, but absolutely worth acquiring as a Swiss army knife for eliminating a ton of VJ headaches in one go.
I don’t have any devices that will easily help me pin down this issue, so I’m going to work under the very reasonable assumption that an upscaler is what I need. It’s a bit of a minefield finding a decent one though by the looks of it. The McClassic is available in my country and isn’t prohibitively expensive, so maybe I’ll try that.
Haven’t used the mClassic myself, but looks like it should be what you’d need to upscale the res from your Pi’s HDMI.
Another cheap(er) alternative that I thought of which may also provide a fix: You could also try using an adapter to convert the Pi’s HDMI to VGA, assuming the Xiaomi projector has an available VGA input. Going on a hunch that since VGA is such a versatile and nearly eternal standard in display technology, using that connector could possibly provide support for more uncommon video signals at their native resolution.