MacBook Pro as external display

Discussion in 'MacBook Pro' started by /V\acpower, Nov 10, 2016.

  1. /V\acpower macrumors 6502a

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    #1
    I was wondering.

    Considering that Thunderbolt can be used to drive an external GPU that could use the built in display of a MacBook Pro.

    Technically, how easy would it be to use a TB3 MacBook Pro as an external display? (so basically use the TB3 port as a display input)
     
  2. Weaselboy Moderator

    Weaselboy

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    #2
    Won't work. That connection is a one way street as far as video is concerned.
     
  3. Outrigger macrumors 68000

    Outrigger

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    #3
    not possible, its output only.
     
  4. 0x100 macrumors regular

    0x100

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  5. /V\acpower thread starter macrumors 6502a

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    #5
    Ok, I know that if you send a HDMI, DP, etc. signal through the TB3 port the computer won't be able to display the feed.

    However, it's still curious that an external GPU can be used to output on the built in screen. I guess that it doesn't send the signal back as a DP signal, however it still mean that somehow it should be possible with the right software.

    Considering the amount of data that the TB3 can receive...
    --- Post Merged, Nov 12, 2016 ---
    My question isn't "how easy it would be for a consumer like me to use the MBP as external display?"

    my question is "how easy technically would it be for a hardware/software company to create a product that could make the MBP work as an external display?"
     
  6. protoxx macrumors 6502a

    protoxx

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    #6
    Few million dollars of development to sell to a handful of users. That's if apple designed the motherboard to accept it.

    Hp for example blocks being able to use an external processor in firmware in their systems with thunderbolt.
     
  7. Outrigger macrumors 68000

    Outrigger

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    #7
    its not about technically possible, who would spend that kind of money to use a 15" as a display? what is the benefit?
     
  8. Weaselboy Moderator

    Weaselboy

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    #8
    I already answered you in post #2. Those TB3 ports do not accept video input. No amount of external cables, adaptors, or convertors is going to change that.
     
  9. cmaier macrumors G3

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    #9
    Says who? That's not how an eGPU works. You drive a monitor with it, not the screen.
     
  10. /V\acpower, Nov 12, 2016
    Last edited: Nov 12, 2016

    /V\acpower thread starter macrumors 6502a

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    #10
    Says the tons of youtube video of peoples running eGPU on MacBook, directly playing on the built in screen.

    That's the thing, the eGPU is rendering the game, and then send it back to the build in screen somehow. That's what bugging me. If an eGPU can do that, then why can't an external device send some form of video signal to the MacBook to be displayed.

    --- Post Merged, Nov 12, 2016 ---
    No you didn't.

    I already know you can't use the TB ports on Macs as simple "display input". Even if you have a computer send display signal through TB and then plug it in a Mac with TB, I know it doesn't work.

    I know it can't be used as DisplayPort Input, or HDMI Input, or whatever other video standard there is.

    But an eGPU is sending video to be displayed on the internal screen. It probably doesn't simply send back DP signal.
    --- Post Merged, Nov 12, 2016 ---
    Yes it's about technically possible. Because that's my question, that's what I'm curious about.

    I'm not asking if this would be a viable product on the marketplace. I don't care. I just want to know what would be necessary technically (if you could write your own software and drivers, and if you could build custom TB3 hardware).

    And don't ask me why I want to know that, because the answer is simply : I'm curious.
     
  11. paaj macrumors member

    paaj

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    #11
    I guess you could add an HDMI capture card and put the window fullscreen.

     
  12. Weaselboy Moderator

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    #12
    Yeah... I did. No video input is accepted period. Have fun arguing with everybody. :rolleyes:
    --- Post Merged, Nov 13, 2016 ---
    I'm not seeing how that would get you video input over one of the USB-C ports to display on the internal screen?
     
  13. paaj macrumors member

    paaj

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    #13
    BluRay/PC/eGPU whatever -> HDMI 1080p output -> capturecard -> USB-C -> app full screen.

    Not perfect or elegant but why wouldn't it work?
     
  14. Weaselboy Moderator

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    #14
    Ah... I see what you mean. I think that would work. But from OP's first post, I don't think that is what he is after. It sounds like he wants to use it as a computer display.
     
  15. /V\acpower thread starter macrumors 6502a

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    #15
    I'm not after a solution for myself.

    I'm just curious about the technical aspect of it.

    And no you didn't answer my question. You stated what I already knew from the start, that you can't simply use the TB3 port for video signal input.

    What i'm curious about is how an eGPU is able to render on the built in screen. Somehow it's sending back informations through TB.
     
  16. Intell macrumors P6

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    #16
    Thunderbolt cannot accept video signals like HDMI or VGA. External video cards work by sending back data that is loaded into the Macbook's local framebuffer and then displayed on screen. It does not send back DVI/DisplayPort/HDMI/LVDS/etc data streams. In theory it would be possible to use a Macbook as an display, but special drivers would have to be written for both the source and the display machines.
     
  17. hiddenmarkov macrumors 6502a

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    #17

    basically. A good working example of this, maybe, would be game recorders out there. I feed my xbone into an elgato recorder, recorder splits out to HDMI to tv and usb out to MBP. MBP runs the elgato software so I see the game output from the xbone on the MBP. Don't know if I can full screen this, I leave the elgato up to work audio adjustments and such. My 7 year old can spike audio channels when excited when game recording, so need the UI functionality.
     
  18. /V\acpower thread starter macrumors 6502a

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    #18
    Thank you very much.
     

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