On Wed, Jul 16, 2008 at 10:08:25AM +0100, Stuart Morris wrote:
It's my understanding that it is the pixel rate that is doubled to meet the minimum bandwidth requirement of 25Mpixels/sec for hdmi. That is pixels are repeated hence doubling the apparent horizontal resolution. This is always the case for the 480i and 576i modes. The modeline you need should be based on standard EIA/CEA-861B timings like this:
# 1440x576i @ 50Hz (EIA/CEA-861B) ModeLine "1440x576" 27.000 1440 1464 1590 1728 576 581 587 625 -hsync -vsync Interlace
Unfortunately I think there is a special flag that must be set to indicate pixel-repetition is being used and I am not sure how you would get a graphics card to do this. I have not tried using the above modeline so I cannot comment on whether it works. Worth a try though.
There is a good list of EIA/CEA-861B modes here: http://www.avsforum.com/avs-vb/showthread.php?t=947830&page=3 I do know the 720p modeline works on my tv. GTF timings generally don't work for hdmi.
The other issue with interlaced modes is how are the odd/even fields synchronised? Is this the same problem with interlaced output on a good old vga output?
I'd like to know this too.. to be able to get 1:1 interlaced output, fields in sync like in the original stream.
-- Pasi