25p and 30p frame modes aren't officially supported within the HDMI spec.

Fist of all in the USA, we use 24 FPS (23.997) or 30 FPS (29.997), not 25. 24 comes from the crank speed of the original movie films and has remained in use do this day, even in digital motion pictures. 25p or 50i was not used in the USA but perhaps this is the standard in the UK and other countries.

But are you suggesting that progressive video is not supported over HDMI? This is the first that I have ever heard that Progressive video is NOT supported over HDMI or that there is some sort of quality issue from converting progressive frames to fields and splicing them back to progressive frames again at the TV. Where are you getting this information from?

I'm no expert but I do know that when I play a blu-ray disc it says that it outputs a 1080 line progressive video over my HDMI cable to my progressive 1080p TV. I am not sure if it is 24fps (source frame rate for film) or 30 fps, but it is certainly supposed to be progressive. I would tend to doubt that my blu-ray player is taking 2 Progressive video frames and converting them to interlaced fields before it passes them through the HDMI to the TV. This is something that I have never heard of before.

According to this web site, http://www.hdmi.org/learningcenter/kb.aspx#32, it appears that HDMI has always supported 1080P video: "HDMI has always supported 1080p resolution, starting from version 1.0 in 2002."