* Calculate fps without distinguish displays, use one fps control
because the controlled side control fps of all displays with one FPS
variable.
* Because all displays decode frame in one thread, when there are N
displays, the video frames received in one second is `fps * N`, so the
calculated decode fps should be divided by N. Because the actual
display count is not obvious in rust, when no data frame is received for 5 seconds, the display is considered inactive, and only the active display is used as the dividend.
Signed-off-by: 21pages <sunboeasy@gmail.com>
