[Ainuke]

Currently rocking 9.2 on a Pi 3B+, looking to turn it into CarPC for my Odyssey minivan

I’m planning to upgrade the 3B+ to a 4 (I did this for my home media player and was smitten by the improvement), but have been using the 3 for proof-of-concept.

I have a HiFiBerry Digi+ hat feeding optical out to my Alpine PDX-800 DSP, amps, etc. That’s working fantastic.
Also using a RasPi 7” touchscreen for display on dash, plus will add some hard controls for volume, play/pause, etc. Also want to use a USB DVD drive for disks.

Where I’m having an issue is with sending video to a separate screen (HDMI monitor) for the back seats. I have no need whatsoever for watching a movie on the dashboard. But Kodi doesn’t allow multiple monitors (unless there’s a workaround I’m not familiar with). I was planning to use a fireTV remote for control from the back seat, so there’s no real need to have dash control while movies are playing for the back seat.

I had a thought that I could just run the Pi into an HDMI monitor and forget about the 7” Pi touchscreen, and use a 7” android tablet or iPad mini in the dash running a Kodi remote app. I would lean towards Android, I think, given that I could probably alter how the tablet displays based on car power state (i.e. screen on when car is running, off when not). Unless I’m mistaken about the degree of control I can exert on the Android.

Ultimately I want a seamless install and UI experience, not something that seems cobbled together. Currently I’m using iPhone Music player AirPlay’d to an Air Port Express that’s connected optically to the Alpine DSP. It works great, but there are a lot of steps to make the music play, and as a result, I’m the only one invested in making it work.
In short, I want a factory-installed experience with the optical audio quality that my stereo and Kodi is capable of.

FWIW, I’m experienced with 3D design and printing, so the physical aspects of the install are not an issue.

Looking for ideas on how to make this work.
Erik

[Klojum]

But Kodi doesn’t allow multiple monitors (unless there’s a workaround I’m not familiar with)

Kodi does allow for a 2nd monitor. On PCs it's possible to have a 2nd monitor/TV, as a long as the resolution and frame rate are identical on both displays.
LibreELEC works a bit "different" (it's still a W-I-P for the RPi4), but the RPi4 can run 2 different monitors in Raspbian Buster. Kodi has stricter requirements though.

[DarrenHill]

@Ainuke - our forum rules (wiki) also only allow a maximum of 4 lines of text in signatures.

Can you please edit your signature essay down to fit that limitation please?

[Klojum]

@Ainuke About your signature, think more horizontal instead of vertical. Also, Kodi details will show up log files.

[Ainuke]

@Ainuke - our forum rules (wiki) also only allow a maximum of 4 lines of text in signatures.

Can you please edit your signature essay down to fit that limitation please?

Sorry about that. I should've known it was too good to be true; every other forum I participate in hits a hard limit and I can't go further. 
Anyway, fixed. Thanks for the gentle prod, Mod...

[Ainuke]

But Kodi doesn’t allow multiple monitors (unless there’s a workaround I’m not familiar with)

Kodi does allow for a 2nd monitor. On PCs it's possible to have a 2nd monitor/TV, as a long as the resolution and frame rate are identical on both displays.
LibreELEC works a bit "different" (it's still a W-I-P for the RPi4), but the RPi4 can run 2 different monitors in Raspbian Buster. Kodi has stricter requirements though.  

Hmmm, OK. I suppose I'll try an image of Buster and see what I can do to make the two monitors agree on a resolution. I'm not planning to go huge with the rear monitor (although a 34" 21:9 would certainly make the kids happy), so maybe I can get the 7" resolution to work. Maybe the Pi screen would downsample?
Thanks for the advice!

-Erik

EDIT: Realizing now that I only have a 3B+ to play with unless I steal the home media unit. Will have to wait on Amazon, I guess...

[Ainuke]

Ok, follow up question...

So, I don’t like the idea of cloning the dash screen to the screen in the back, regardless of the resolution limitation. I don’t want video playing on the dash while I drive, at all. If there’s no option to just have controls active on the dash with video playing on the rear screen, I’d rather the dash screen just be blank (I’m planning for hard button controls anyway, so I don’t need the touchscreen at that point).

So is there a way to have Kodi (not the pi) start with a screen preference? For instance, with the Carbon Car skin, I can have buttons on the home screen that run scripts (IIRC). If I want to play a video, can I have a script that restarts Kodi with the rear screen preferred (through an alternate config file), and have a similar function on the rear config that restarts Kodi with the front screen preferred? If needed I can use the I/O pins on pi to run a relay that alternates power to each screen, but I’d rather do it with software only.
Or (I haven’t experimented too deeply with User Profiles), can I specify a screen preference (dash or rear) with a User profile and just have a front user and back user?

I have a pi 4 now, BTW. I managed to brick the 3B+ messing around with alternate touchscreen power schemes, so I thought I’d start by asking, rather than doing.

Erik

[black_eagle]

You should be able to choose the video output in settings->system->display->monitor .  However, for your usecase, I would just go with HDMI output to the rear and an android tablet in the front running a browser and connected to Kodi's webserver.  There are several different web interfaces you could use. See https://kodi.wiki/view/Web_interface and https://kodi.wiki/view/Category:Web_interface_add-ons

[Ainuke]

You should be able to choose the video output in settings->system->display->monitor .  However, for your usecase, I would just go with HDMI output to the rear and an android tablet in the front running a browser and connected to Kodi's webserver.  There are several different web interfaces you could use. See https://kodi.wiki/view/Web_interface and https://kodi.wiki/view/Category:Web_interface_add-ons

Thanks for the response. 
With the touchscreen and HDMI monitor both connected, I get no option under "Display" to choose monitors. It's just the pi touchscreen resolution greyed out. Is there something somewhere else that I need to enable?  EDIT: perhaps in Pi 4 config?

I like the Android plan, I think. All I have to do is justify the $100 cost; if I go that route, I think I want to get cell data enabled tablet so I can use maps/directions.

Erik