[mythtv] NVidia Shield screen resolution

Peter Bennett pb.mythtv at gmail.com
Wed Aug 1 22:27:40 UTC 2018

On 08/01/2018 05:17 PM, Peter Bennett wrote:
> On 07/30/2018 11:17 PM, Mark Spieth wrote:
>> On 31/07/18 08:52, Peter Bennett wrote:
>>> On 07/29/2018 06:58 PM, Mark Spieth wrote:
>>>> On 30 July 2018 08:29:31 GMT+10:00, Peter Bennett 
>>>> <pb.mythtv at gmail.com> wrote:
>>>>> On 07/29/2018 06:14 PM, Mark Spieth wrote:
>>>>>> Is this also with video playback or UI only?
>>>>> It is both. In the Setup->Appearance I tried changing the GUI size to
>>>>> 1280x720. That should have used one third of the width and height, 
>>>>> but
>>>>> actually used two thirds of the width and height.
>>>>>> Is it different with media codec vs GLES?
>>>>> No - media codec is also using OpenGL for output, the same as used by
>>>>> software decoding. It may be different with a surface but there is no
>>>>> code to use a surface at this time.
>>>>>> CPU definitely takes a hit for a 4K screen though.
>>>>>> Will do some research on this.
>>>> Smells like a qt or platform gl problem. Need to check qt source 
>>>> for 1920 restrictions.
>>> FWIW 4K video works fine with Qt on Linux. Also I tested the 4K 
>>> video with Kodi on Shield and it is playing with the full 4K 
>>> resolution on my monitor, so it is possible to do it. I did scan 
>>> carefully through the Kodi manifest but I could find nothing that 
>>> might help me.
>> Here is something to look at.
>> in qt source qtbase/src/plugins/platforms/android/androidjnimain.cpp
>> there are 2 functions
>> createSurface and setSurfaceGeometry. This is the lowest level before 
>> android and applies to qt's gl surface it allocates at start.
>> instrument with some __android_log_print to see what height and width 
>> are being used. These will appear in logcat.
>> Make changes and then makelibs.sh without clean. Wont take as long as 
>> clean and you dont need to export any diffs either.
>> Changes are preserved. since git is used for baselining you can git 
>> diff to get your patches too.
>> Note this is the file that launches main() in mythtv. see 
>> startapplication which launches a thread which then runs main(). This 
>> is called from the java initial code (some in qt and 1 overridden in 
>> our android_package_source tree.
>> Not sure when I can test this but may give you some hints as to where 
>> the 4k is going.
>> All parts of our android app is using gl for rendering.
>> You can also go for gdb and break in these functions if you are extra 
>> adventurous.
>> HTH
>> Mark
> This is what I get logged
> androidjnimain.cpp setDisplayMetrics wP=1920 hP=1080 dWP=1920 dHP=1080 
> xdpi=213.000000 ydpi=213.000000 sD=2.000000 d=2.000000
> qandroidplatformintegration.cpp setDefaultDisplayMetrics gw=1920 
> gh=1080 sw=229 sh=129 scrW=1920 scrH=1080
> androidjnimain.cpp setSurfaceGeometry x=0 y=0 w=1920 h=1080
> setDisplayMetrics parameters logged are
>         widthPixels, heightPixels,
>         desktopWidthPixels, desktopHeightPixels,
>         xdpi, ydpi,
>         scaledDensity, density);
> Those last two parameters of setDisplayMetrics look like a possible cause
> scaledDensity=2 and density=2. Documentation says scaledDensity is for 
> fonts and density is logical density.
> QtLayout.onSizeChanged (java)
>  calls android.view.Display.getMetrics()
>  calls QtNative.setApplicationDisplayMetrics()
>    calls setDisplayMetrics (c++)
> /public void getMetrics (DisplayMetrics outMetrics)//
> //
> //Gets display metrics that describe the size and density of this 
> display. The size returned by this method does not necessarily 
> represent the actual raw size (native resolution) of the display.//
> //2.//*It may be scaled to provide compatibility with older 
> applications that were originally designed for smaller displays.
> */How do we explain to android this is not an older application like 
> that? Will each android device do its own thing here?
> /DisplayMetrics.density//
> //The logical density of the display. This is a scaling factor for the 
> Density Independent Pixel unit, where one DIP is one pixel on an 
> approximately 160 dpi screen (for example a 240x320, 1.5"x2" screen), 
> providing the baseline of the system's display. Thus on a 160dpi 
> screen this density value will be 1; on a 120 dpi screen it would be 
> .75; etc. //
> /
> Maybe we should use getRealMetrics instead of getMetrics I can try that.
> Otherwise multiply screen height and width by density.
> Either way involves changing some QT code ???
> Peter

No solution in sight - with the display physically at 1920x1080 or 
3840x2160 the metrics are the same. Also using getRealMetrics returns 
the same in both 1920 and 3840 resolution cases..

All 4 cases return the same values -
androidjnimain.cpp setDisplayMetrics wP=1920 hP=1080 dWP=1920 dHP=1080 
xdpi=213.000000 ydpi=213.000000 sD=2.000000 d=2.000000


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