Actually, I also want to change audio language, change subtitle language, etc.
There should be a context menu during movie play, but I cannot access it using a game controller. 
I tried every combination I could think of!
Am I missing something obvious?
It works fine with Recalbox (I tested in USB mode). And it looks really cute.
But I can't recommend this controller to any gamer, even though it's linked on the Recalbox site store.
For US$43 (!!!), I expected something very good indeed. But its d-pad is a disgrace. There are better d-pads on aftermarket controllers that cost $10. Even on simple games that don't require precision I find that this d-pad fails me and easily registers the wrong clicks. It is not fun to fail at a game because the controller sucks.
Also, its lights keep flashing in whatever mode its in, whether USB or Bluetooth. It's annoying.
There are good things about the 8Bitdo: it supports many different compatibility modes (hard to configure) that could help emulation freaks who need to work with Macs and Android and other specialized platforms. But none of those are important to Recalbox users. At the end of the day, if the d-pad sucks, it just plain sucks.
If you are looking for an aftermarket controller, I had good results with the $20 Gamesir G3s (it also has a Bluetooth version, though I don't know if that will work with Recalbox). Its d-pad isn't as good as PlayStation or even Nintendo controllers, but it's at least as good if not better than the Xbox 360. And it works with Android, too.
Anyway, please save your money and don't buy from 8Bitdo if you really want to enjoy your games!
@FAGUDES Sorry, I meant the "?" to represent a number. Press the TAB key instead of "?" and the terminal should show you which options are available to you. It might seem a bit awkward, but this is a great way to see exactly how Recalbox is seeing your controllers!
@Substring I'm confused by your answer to me. 
You edited the wiki 10 days ago but you don't have the link to it? Does that mean you edited it or forgot ...?
@FAGUDES Try my debugging trick: ssh into your box and run "jstest /dev/input/js?" with the various "joysticks" you see there, and try to see what each joystick is. We can start with that and try to figure out what mupen64 is trying to use...
@Substring Can you point me to the wiki page? I can't find it.
@Substring Is this documented anywhere in the wiki? This is an interesting little corner of Recalbox.
I'm realizing more and more that mupen64plus is the weirdest part of the system.
Come to think of it, I still don't have an explanation as to why my 8bitdo isn't working for N64 ...
It seems that the whole interface between Recalbox and mupen64plus is a bit buggy. I think everything that uses libretro would work the same!
Hey everyone, I have found the issue.
To connect the PS2 controller, I am using a "duo" USB adapter. This adapter allows for two controllers to be connected. Using jstest, I noticed that the first controller is assigned from the right port, and second from the left port. Originally, I connected my controller to the left. Once I switched to the right (and reconfigured via Recalbox) then N64 worked fine.
So, I'm not really sure what is causing this. I am guessing because of how mupen64plus works, it uses the identifier in the ini file (in this case "Twin USB Joystick") to match the controller, and it just matches the first one that it finds with this name. Because there are two, but the first isn't connected, that is what it is using.
I'm not sure if this bug can be fixed, but I hope so. If not, can I recommend putting something about this in the Recalbox wiki so that if people search they can easily find a solution? Here's some initial content:
Configure PlayStation DualShock 1 and 2 Controllers
Most emulators will work automatically.
However, for N64 there is one issue. If you are connecting your controller using a two-controller-port-to-USB adapter, then one of these ports will be considered "controller 1" and the other "controller 2". In one test, "controller 1" was assigned to the right port on the adapter. N64 emulation will expect you to be using "controller 1". If you are having issues, try connecting your controller to the other port and reconfigure it.
@paradadf Maybe I wasn't clear: HOTKEY+START works, but START doesn't work in the game. So, something is correct in the config, but something else isn't.
@Substring Thanks, this is moving me forward. I tried to edit "/recalbox/share/system/configs/mupen64/InputAutoCfg.ini", but it seems that this file gets overwritten be Recalbox. I also see an "Input-SDL-Control1" section in "/recalbox/share/system/configs/mupen64/mupen64plus.cfg", but it says at the top of this file that it is "written by the Mupen64Plus Core library", so I guess I shouldn't be editing.
So, I'm stuck now:
Running 4.0.0 beta 6 on rPi 3B.
I'm trying both a PlayStation 2 controller with a USB adapter and an 8bitdo Pro connected via USB.
Both of them register the hotkey just fine -- so I'm able to save/load and exit a game.
However I can't play the game. START does not even work.
Is this an issue with the beta? Or is there something I am missing?
I do know that N64 emulation goes through mupen64plus rather than libretro, but when I look at the mupen64plus InputAutoCfg.ini it seems to have all the controllers configured. (Great job, by the way, of adding soooo many controllers to the list! To bad it's not working for me.)
I know the controllers work, but does rumble/vibration work, too?
Specifically for PS1 and PS2 I intend to use a USB adapter dongle. I know that on Windows you need to install a special driver to make rumble work with the dongle, but is that true on Linux and specifically with Recalbox?
I know there are ways to connect these controllers to the Raspberry Pi's GPIO connector. If you do so, will rumble work immediately with Recalbox?
I'm super impressed with Recalbox's support for the PS3 wireless controller. However, it's not clear to me whether it works with rumble, too. Can anybody verify?
I hope to get concrete answers here, as I'm planning a big project based on Recalbox and am trying to pick the best controller. Telling me that it "should" work won't help me, I really need facts from somehow who has tried it. Thanks!