Play DVD video in fullscreen mode?

I just installed a Android 4.4.4 Car DVD GPS player in my car (2011 Toyota Venza). Everything is working well, except that I cannot play video from DVD disc in full screen mode. There are always two black bars at the top and bottom of the video (see attached). I know for sure that picture format of the DVD is 16x9, and it plays properly in fullscreen mode with a regular DVD player connected to 1080p TV. However, with the built-in DVD application, there's no option to adjust the screen size of the video to occupy the entire screen (i.e. no black bars).

I've contacted the seller (Witson), and they said that this is by design. There's no way to remove these black bars. All video playbacks from DVD discs will experience either 2 bigger black bars, or 2 smaller black bars. This is very annoying to me since the video playback is not in appropriate aspect ratio (it looks squeezed).

Has anyone else experienced similar issue? Is there anyway to resolve this issue? Can we install another DVD playback app in place of the built0in one? If yes, can I get the APK and instructions on how to replace the existing DVD playback app?

Thanks