Chroma Sample - Position & Size

Hi members! I am writing a software to automate a few things with macros and I am struggling to understand the concept behind the values for position and size for the "chroma sample" cursor.

I recorded a macro and configured the size of the cursor to its minimal value (strangely that is the odd number of 0.0630036) and then moved it to the top left, bottom left, bottom right and top right corner with a pause frame between each, so we can see each position in the macro below:

Code: Select all

<Op id="AdvancedChromaKeyCursorSize" mixEffectBlockIndex="0" keyIndex="0" size="0.0630035"/>

TOP LEFT
<Op id="AdvancedChromaKeyCursorXPosition" mixEffectBlockIndex="0" keyIndex="0" xPosition="-32.768"/>
<Op id="AdvancedChromaKeyCursorYPosition" mixEffectBlockIndex="0" keyIndex="0" yPosition="15.814"/>
<Op id="MacroSleep" frames="1"/>

BOTTOM LEFT
<Op id="AdvancedChromaKeyCursorXPosition" mixEffectBlockIndex="0" keyIndex="0" xPosition="-23.296"/>
<Op id="AdvancedChromaKeyCursorYPosition" mixEffectBlockIndex="0" keyIndex="0" yPosition="-20.314"/>
<Op id="MacroSleep" frames="1"/>

BOTTOM RIGHT
<Op id="AdvancedChromaKeyCursorXPosition" mixEffectBlockIndex="0" keyIndex="0" xPosition="32.767"/>
<Op id="AdvancedChromaKeyCursorYPosition" mixEffectBlockIndex="0" keyIndex="0" yPosition="-10.929"/>
<Op id="MacroSleep" frames="1"/>

TOP RIGHT
<Op id="AdvancedChromaKeyCursorXPosition" mixEffectBlockIndex="0" keyIndex="0" xPosition="22.912"/>
<Op id="AdvancedChromaKeyCursorYPosition" mixEffectBlockIndex="0" keyIndex="0" yPosition="24.171"/>
<Op id="MacroSleep" frames="1"/>

Does any of this make any sense to anyone? Let's just look at the values for x:

All the way left: -32.768 and -23.296 for top left and bottom left
All the way right: 32.767 and 22.912 for bottom right and top right

How does that concept work?

It's a virtual value that represents the position on the screen. It's a 16-bit signed value where (0,0) is at the center of the screen. It's not in pixels so that it's resolution independant and works the same if you are working in 720p, 1080p or 2160p.

Because a video picture is not a square you have less range in the vertical space than in the horizontal space.

Hi, yeah I got that But if you look closely at the values I am getting.


X value for top LEFT: -32.768
X value for bottom LEFT: -23.296

Both times, I went all the way left and I am getting very different values.