HDMI transceiver wiring

[hamster]

[tnt]

Yes, exactly what hamster said.

You can't transmit RGB, so you have to pay the price of a RGB -> YCbCr code inside the FPGA (because the frame buffer is most likely RGB).

But more importantly this is only 4:2:2 YCbCr (i.e. the chroma channels are being downsampled). For a movie that might not matter much, but things like sub-pixel font rendering on a desktop or sharp synthetic image rendering will be affected.

Wiring the upper 8 bits only would allow 4:4:4 RGB 8 bits. If you want 10 bits, you can even just wire the upper 15 bits. That's still less wires than the previous case. And if you want to still be compatible with the current, you could even just wire them in //.
So that fpga pins are connected to two data pins to allow either modes to be used. This way it still works with the current config, but you can also change the fpga to use native RGB.

[shodruk]

Does nomal TV support RGB HDMI?

[tnt]

Yes

But even if somehow you found one that couldn't, wiring the upper data block allows both RGB _and_ YCbCr 4:4:4

[hamster]

If anybody has the Zedboard prototype and is interested, I've got the code to drive the ADV7511 HDMI transmitter, with working colour at http://hamsterworks.co.nz/mediawiki/ind ... rd_HDMI_v2. At the moment it just displays R/G/B/Black/White colour bars, but it is a lot further along than anything else I've seen in the wild.

I've had a look at the ADV7513 programming guide (the part that is on the production Parallella board) and it looks to be much the same - there is a key setting in Register D0 for using DDR transfers, and the colour space conversion set-up is all the same.

[aolofsson]

Nice! The current ADI implementation is quite large so I am sure a folks would appreciate a clean open license version for the Parallella.