Changes

Jump to: navigation, search

VIDI digitizer

364 bytes added, 14:07, 8 May 2010
/* Scanning Modes */
The software supports 3 modes (at hardware side, there are only 2 modes):
* Mode 2 - 640x200x1 - true hardware mode(0=black, 1=white)* Mode 1 - 320x200x4 - true hardware mode(0=black, 1=dark grey, 2=white, 3=light grey)
* Mode 0 - 160x192x16 - special software mode: the software performs sixteen Mode 2 scans (with different brightness settings in each pass), and combines them to a 16-color image. Obviously, this method works only with still images (camcorder aimed at still image, or VCR with "freeze picture" mode). Moreover, the CPC with [[CTM640/CTM644]] colour monitor can't display 16 grayscales so the picture will look like crap, however, it will look pretty much perfect on a [[GT64/GT65]] green monitor. The software scans only 192 lines in this mode (not 200 lines), but this is just due to lazy programming (the programmer didn't handle the region "under" the OSD menu at the bottom of the screen). In mode 0 scanning, the user/software selected brightness is ignored (because the whole sixteen I/O selectable brightness values are used for the sixteen passes), so, brightness can be adjusted only via the potentiometer.
 
For the two hardware modes, the bits in the capture bytes are having the same format as CPC VRAM (observe that in Mode 1, white is color 2, (ot color 3). For the software mode, obviously, the format depends on the software (the VIDI software uses CPC VRAM format, with color 0..15 = black..white).
=== Disassembly ===
6,388
edits