More from composite out

[michele.x]

Hello all,
It's possible to modify the GPU code to have an extra option for the composite output, making possible to have a progressive mode output?

I was thinking to add a parameter, called sdtv_progressive_mode, that with value 0 makes the normal interlaced mode as is working now.
With the value 1 the GPU disables the interlacing, mantains the 15 kHz horizontal sync, and halves the vertical resolution. This is really useful for all the people with a CRT lying somewere wanting to make some retro emulation more retro.
With the value 2 the GPU disables the interlacing, mantains the 480 lines or 576 lines vertical resolution, but doubles the horizontal sync, emitting a progressive scan signal. It could be feed to a progressive scan TV set with component in, or adding a simple sync separator circuit it could drive an old VGA monitor, albeit in black and white (or green and white with a colour VGA monitor).

Not knowing about the GPU layout I don't know it's like shuffle some register constants or it's a difficult task, but this tweak I think could be useful for some applications, including the "I have a lot of old CRT VGA monitors taking dust" one.

[jamesh]

I haven't the faintest idea, but Dom might know. I'll email him.

James

[plugwash]

If you implement this sort of thing then if possible you probablly also want an option to disable generation of the chroma subcarrier.