As described in https://forum.doom9.org/showthread.php?t=186910 the current scene change detection with SAD for non motion compensated frames is not perfect and users can try to use mvtools-based scene change detection. So it is nice to have additional input of the clip with a scene change signal. The selection between internal and external methods may be based on the presence of the provided external clip. As I see from MSCDetect filter https://github.com/pinterf/mvtools/blob/a488b095c4bdc8d81abfd952ab534c015a9d45b7/Sources/MVSCDetection.cpp#L55
It outputs zeroed frame if no scene change detected (from current frame to requested frame number ?) and non-zero content if scene change detected.
As described in https://forum.doom9.org/showthread.php?t=186910 the current scene change detection with SAD for non motion compensated frames is not perfect and users can try to use mvtools-based scene change detection. So it is nice to have additional input of the clip with a scene change signal. The selection between internal and external methods may be based on the presence of the provided external clip. As I see from MSCDetect filter https://github.com/pinterf/mvtools/blob/a488b095c4bdc8d81abfd952ab534c015a9d45b7/Sources/MVSCDetection.cpp#L55
It outputs zeroed frame if no scene change detected (from current frame to requested frame number ?) and non-zero content if scene change detected.