player screen does not scales on large screen when video resolution is low

[rtechapp]

i am using better player v0.0.82 and i have problem in scaling the video when i try to play low resolution ( eg. 480p or 720p) in large screen say 50 or 55 inches tv and it only shows the video in small screen and rest of the screen remains green screen.
but its scaling well on emulator and works perfectly.
i have tried all possible fit property
say fit fill cover contain
but no luck
if anyone can help then please assist me.
i am attaching tv screen picture and emulato

r screen as well along with player file codes

video player file contents

void initSettings() async{
_animated_controller = AnimationController(vsync: this, duration: Duration(milliseconds: 450));
_animated_controller!.forward();

 prefs = await SharedPreferences.getInstance();
 _subtitle_enabled  =  prefs?.getBool("subtitle_enabled");

 Size screenSize = MediaQuery.of(context).size;
 double aspectRatio = screenSize.width / screenSize.height;
 BetterPlayerConfiguration betterPlayerConfiguration =
 BetterPlayerConfiguration(
   controlsConfiguration: BetterPlayerControlsConfiguration(
     showControls: false,
   ),
   aspectRatio: aspectRatio,
   fit: BoxFit.fill,
   fullScreenByDefault: true,
   autoPlay: true,
   subtitlesConfiguration: BetterPlayerSubtitlesConfiguration(
     backgroundColor: _list_text_bg[_subtitle_background!],
     fontColor: _list_text_color[_subtitle_color!  ],
     outlineColor: Colors.black,
     fontSize: _subtitle_size!.toDouble(),
   ),
 );

 _betterPlayerController = BetterPlayerController(betterPlayerConfiguration);


 _setupDataSource(widget.selected_source!);
 _hideControllers();
 if(_subtitle_enabled! == true){
   _applySubtitle();
 }

}

[rtechapp]

one thing i forgot to tell that when i use fijkplayer then its scaling correctly.