SGI's aren't always nice guys

I don't know if you feel like I do, but I found that the tables in the Chapter 13 of SGI's Iris Digital Media Programming Guide: "Using VL Controls" were the more obscure part of the documentation (despite the fact I'm an SGI fan). I finally understood (after having checked by program) that controls like VL_VINO_INDYCAM_SATURATION are fractions, not integer. The table is supposed to give the type of the controls (is it really ?). So I merely understand that 0 = off, 1 = on should be a boolean control, but what does "0,255,255" means ? Are we really supposed to understand that this is the range of a fraction ?


Anyway, if you've felt lost for at least one hour, as I did, here is as an example the result of a vlGetControlInfo() on VL_VINO_INDYCAM_SATURATION:

name indycam_saturation
ControlType 'VI\000\006'
ControlClass 1 (SLIDER) (as can be seen in the VideoPanel / IndyCam Controls)
ControlGroup 0x8002, that is SIGNAL (this controls a signal) and "Pro". I'm not sure to understand what "Pro" means, except that the signal is in the Pro menu of the VideoPanel, but I think that "Pro" is here to flag very poorly documented controls...
ControlValueType 1, That is Fraction


Two things you should know:
  1. The values are always negative.
  2. The y offset refers to field, not frame. If you don't understand what that means, just divide by 2 the value you think is the right one for the y offset.

Some useful informations

By the way, if you're lost when doing some video stuff on your SGI, you should have a look to the excellent Lurker's Guide to Video by Chris Pirazzi.
Christophe Tronche,