Canvas
The canvas tells the player how to interpreted a side-by-side recording. The values are based on coordinates in %.
A double 16:9 input in a centered side-by-side as shown below would become:
0,25:50,75;50,25:100,75
In combination with Slide Source the transcoder knows which part of the screen to use for generating index slides and OCR.
NOTE: at this time the player only handles 2 sources.