https://www.alteraforum.com/forum/attachment.php?attachmentid=8823 I dont know how the RGB444 is transfered in this situation. The parameter bits per pixel per color plane = 8 -> RGB888 isn't it? So, it is conflicted with RGB444 output format?
The 4:4:4 has no relavence to RGB. the 4:4:4 relates to YCbCr, where you can drop half the Cb and Cr values in the data stream and still get a very good quality picture (4:2:2). You can even go further and drop half again for 4:2:0 (its really 4:1:1) which is what is used in television tranmission.