[mythtv] NVidia Shield screen resolution

[Mark Spieth]

On 7/30/2018 6:55 AM, Peter Bennett wrote:
> I cannot find a solution to this, Android is firmly in charge and 
> thinks it knows what is best for me.
>
> On Linux, I can connect MythTV to a 3840x2160 screen and it uses the 
> full screen and plays 4K video perfectly (using vaapi). I have 
> committed a change that updates a few places in the code where 
> 1920x1080 was hardcoded as the maximum. None of those had actually 
> prevented 4K video from working.
>
> I have a 3840x2160 screen connected to my NVidia Shield. In the 
> Android setup the resolution is set at "4K". The screen OSD itself 
> confirms that it is running at 3840x2160. However, QT informs us that 
> the screen resolution is 1920x1080. Playing a 4K video file results in 
> it being resized to 1920x1080 and then displayed as 3840x2160 via some 
> android scaling operation.
>
> In the manifest (supports-screens) I tried adding 
> android:xlargeScreens="true". This did not help:
>
> <supports-screens android:xlargeScreens="true" 
> android:largeScreens="true" android:normalScreens="true" 
> android:anyDensity="true" android:smallScreens="true" />
>
> I also tried android:anyDensity="false" . This made things worse - QT 
> gave the screen size as 960x540 and everything was blurry. However 
> this does prove that android is ready and willing to scale the output 
> as it sees fit, and I don't know how to prevent that from happening.
>
> I also tried removing the supports-screens setting altogether. Kodi 
> does not use that setting in its manifest. That did not help either. 
> Still 1920x1080.
>
> I tried QApplication::setAttribute(Qt::AA_DisableHighDpiScaling); in 
> the code in case it is QT that is messing with this. That did not help.
>
> I set the program arguments to "-v general,playback,libav,gui". Then 
> when a video starts there is a log message with the resolution, which 
> is obtained for QT desktop widget:
>
> MythUIHelper: Using screen 0, 1920x1080 at 0,0
>
> I found a web site that tells how to modify Android's dpi setting but 
> that does not seem to be available on the Shield 
> (https://www.thecustomdroid.com/change-dpi-density-android/).
>
> Playing a 4K video on the Shield and looking at some small writing in 
> the video, I can see it is jagged, unlike when playing through Linux.
>
> Android may be getting a screen size in inches from somewhere and 
> deciding that I don't need the full resolution. Or else it is deciding 
> that MythTV developers are too stupid to create an application that 
> runs at 4K so they are helping us by resizing it down to 1080.
>
> My next step would be to create a basic "Hello world" android 
> application and see what screen resolution I get. Since I have never 
> created an android application from scratch, I don't think I will be 
> trying this. 
Is this also with video playback or UI only?
Is it different with media codec vs GLES?

CPU definitely takes a hit for a 4K screen though.

Will do some research on this.

Mark