The pixel aspect ratio (PAR) of the item.
• In a CompItem, the value is linked to the composition.
• In a FootageItem, the value is linked to the mainSource object.
The value you retrieve after setting may be slightly different from the value you supplied. The following table compares the value as it appears in the UI with the more-accurate value returned by this attribute.
PAR in the After Effects UI PAR returned by the pixelAspect attribute
Floating-point value, in the range [0.01..100.0]; read/write.