• General

  • Do I understand correctly Miracast is not supported by GOS?

I was reading about Miracast on Wikipedia and this article, "Top 5 Miracast App for Android" was one of the references.

I have only skimmed through and have not tested any of the apps so this is definitely not a recommendation, but thought I would link it here in case it ends up being useful

GrapheneOS

So is DisplayPort a cable or a screencasting device? Is "alternate mode" an option you can select on it?

If I may ask, can you post a link as an example of what it is so I know what to buy for my Pixel 6 Pro?

      Displayport mode is basically connecting your phone to a screen or a projector with an USB c to displayport cable.
      I just tested it, connectivity is very straightforward and it kinda works, but for some reason the output has a resolution so low you can't even read text on screen.

      I can reproduce the issue and test multiple screen, if someone is interested solving that.

        Hepativore If I may ask, can you post a link as an example of what it is so I know what to buy for my Pixel 6 Pro?

        DisplayPort alt mode requires an 8 or later, see the post before yours (GrapheneOS).

            7 days later

            GrapheneOS The security issues were a major factor in it being removed from AOSP and from Pixels, since it wasn't being actively developed or maintained anymore.

            Based on a fact that Samsung relies heavily on Miracast for their premium Galaxy S series for Samsung DeX wireless (not speaking of Microsoft itself), I assume it's more of a business decision from Google to force everyone to use Chromecast and not the security issues in the 1st place.
            Samsung handles it via their closed-source Quick Share app (not available via google play from what I recall).

            It's hard to trust google's closed-source non-configurable device (Chromecast) to handle privacy.

            Anyway, thank you for re-confirming it!

            • de0u replied to this.

                Hepativore So is DisplayPort a cable or a screencasting device?

                DisplayPort is a communications protocol used to connect a monitor to a computer. One you're probably more familiar with is HDMI. DP is better than HDMI in that you can daisychain multiple monitors to a single port. You can also use an active converter to generate an HDMI signal from a DP.

                So;

                DP source --> Monitor1 --> Monitor2 --> ... --> MonitorN

                USB-C alternate mode can carry a DisplayPort signal, if it happens to be wired up to the USB-C port. This is why not all phones can drive DisplayPort. The SoC has to HAVE DisplayPort, and it has to be physically wired up to the USB-C port.

                • hnn8 replied to this.

                    mmobder Based on a fact that Samsung relies heavily on Miracast for their premium Galaxy S series for Samsung DeX wireless (not speaking of Microsoft itself), I assume it's more of a business decision from Google to force everyone to use Chromecast and not the security issues in the 1st place.

                    If Samsung uses their own proprietary code to talk to Miracast devices, that might indicate that indeed something was wrong with the code that Google deleted from AOSP.

                      mmobder It's hard to trust google's closed-source non-configurable device (Chromecast) to handle privacy.

                      I don't disagree entirely... but if Samsung's Miracast code is closed and the code for Miracast display devices is also closed, is it easier to trust that ecosystem?

                          Canardo_Sanchez for some reason the output has a resolution so low you can't even read text on screen.

                          This is not the case for the majority of people that have used display port alternative mode on Pixel 8 and Pixel 9 series phones. I use it regularly and it works fine for me.

                          There is a problem with your setup. Make sure you have a good cable. Could also be an issue with the display or even usb port on phone.

                              de0u Miracast protocol itself is open to the public https://www.wi-fi.org/file/miracast-specification (certification by WiFi alliance is not mandatory).
                              It's kinda expected that Samsung's implementation of their sender is proprietary. Implementation of MS receiver/dongle is irrelevant at all.

                              The fact that the Miracast receiver device doesn't require to be connected even to WiFi (CC can't work without WiFi) not speaking of internet, makes it insecure just on the level of protocol and can be examined.

                              No chance Miracast dongle will phone home) if not connected to wi-fi.

                              And Chromecast is kinda on the opposite pole of that state.

                                Carlos-Anso
                                Thanks for the reply.

                                I don't know what happened but I have since then switched to USBc > HDMI on my projector and everything works as expected here, contrary to USBc > displayport on my monitor, which I don't care much about anyway.

                                I wished we could cast different aspect ratios to fill the whole space in landscape mode, but it's beyond GrapheneOS scope and other than that it is indeed 100% functional.

                                    hnn8 The kernel does by definition. As for the other layers, I don't know. Maybe somebody with a new enough phone can give it a try?