RGB2HDMI profile update?

[sigma7]

sigma7 recommends substituting 3,4 for 2,3 in the geometry= line, preferring a pixel ratio of 4/3 to 3/2 (height/width).

I've not yet tried that myself, and now doubt that it would make an improvement in accurately representing the CRT image. The suggestion was based on calculations using a raster adjusted to fit most of the viewable area through the front panel in conjunction with the observation that the usual recommendation for a 3:2 aspect ratio of pixels does not look right.

Since then, anotherLISAguy measured an actual alignment graticule (a very rare service part) and we found that the "official" CRT adjustments put the aspect ratio of the pixels between 3:2 and 4:3, but closer to 3:2.

[Lisa2]

I've decided to give this another look. I can confirm that I need to turn 75R termination ON for the Lisa 1 and OFF for the 2/10.

Thank you for confirming this!   

Due to the composite video's analog signal path and 40+ year old Lisa hardware combined with variations in RGBtoHDMI builds, this solution is never going to be plug-and-play.  Some tweaking of the settings is bound to be required for each user. 

Rick

[sigma7]

Here are two RGBtoHDMI profiles that I've got working on a Lisa 1/5 for H (rectangular pixel) and 3A (square pixel) ROMs.

These are using the YUV CPLD configuration, so are stored in eg.

Profiles/6-12_BIT_YUV_Analog/Apple_/Apple_Lisa_R2_.txt
Profiles/6-12_BIT_YUV_Analog/Apple_/Apple_Lisa_S2_.txt

The underscore preceding .txt is needed for the profiles to appear as an available choice when "mono_board_detected()".

It may be that the RGB CPLD configuration would be more tolerant of variations between machines... dunno. The CPLD configuration can be changed from "Settings Menu"-"Update CPLD Menu", wherein I see BBC, RGB, and YUV options.

Some parameters in the sampling= line apply to only one of RGB/YUV, and other settings apply to both, but not all in an identical way. I'll try to document what I've mis/understood in case someone feels like taking it farther.

After barely starting to understand what the parameters are for, I'm truly amazed at the accomplishment this device represents.

I focused on trying to understand the geometry and sampling lines, so I don't know if the lines after "palette=" are relevant, unnecessary artifacts from my fiddling with options, or somehow specific to my setup.

Rectangular Pixels (eg. H ROMs) with 3:2 pixel aspect ratio output:

Code Select Expand

sampling=2,2,2,2,2,2,2,0,1,0,4,0,0,0,0,4,0,1,1,0,77,256,256,256,44,256,256,256
geometry=88,8,720,364,720,364,2,3,0,0,20375213,896,5000,379,4,0,0
palette=Mono_(2_level)
palette_control=3
ntsc_type=2
pal_oddline=2
normal_deinterlace=1
ffosd_overlay=1
scanline_level=0
Square Pixels (3A ROMs) with 1:1 pixel aspect ratio output:

Code Select Expand

sampling=2,2,2,2,2,2,2,0,1,0,4,0,0,0,0,4,0,1,1,0,77,256,256,256,44,256,256,256
geometry=88,8,608,432,648,438,1,1,0,0,20375213,768,5000,450,4,0,0
palette=Mono_(2_level)
palette_control=3
ntsc_type=2
pal_oddline=2
normal_deinterlace=1
ffosd_overlay=1
scanline_level=0
Thanks to Sapient Technologies for providing the RGBtoHDMI device used for this experimentation.