Changes the source of this FootageItem to the specified file. In addition to loading the file, the method creates a new FileSource object for the file and sets mainSource to that object. In the new source object, it sets the name, width , height , frameDuration, and duration attributes (seeAVItem object” onpage30) based on the contents of the file.
The methodpreserves interpretationparameters from theprevious mainSource object. Ifthe specified filehas an unlabeled alpha channel, the method estimates the alpha interpretation.
file An ExtendScript File object for the file to be used as the footage main source.