MP4 at 1998 x 1080 possible

We were really hoping that the MP4 h264 support of IE9 is good. We are trying to display html5 MP4 Videos at sizes of 1998 x 1080 and 2048 x 858 Pixels. These are very often used 2K resolutions. We tried all kinds of encoding profiles and levels (baseline, main, 4.1., 4.2. even 5). But it was not possible the display anything bigger than 1920 x 1080. Is there ANY possibility to display an MP4 Video bigger than 1920 x 1080 in html5 on IE9? Thanks for any help...