4k video goes black in fullscrn


we are playing with H265 in 4K. it works up to 2880x1800, which is the biggest non-4K screen we can test. On the 4K screen, if the hdmi is set to HD, the 4k video starts, but only the left-top quarter is visible, as expected. However when I set the hdmi output to 3840x2560, the output will be black.

Also, if we try to place 4x HD H264 images to fill a 4k monitor, the same thing happens.

The black might be a result from an HVS underflow. Basically the Pi is too slow to generate the HDMI signal fast enough and the display signal is lost. Are you using 4K at 60Hz? What’s the framerate of the video?

it seems that the video was 10bit and bitrate went too high. It was 24p. Thanks!