Hi,

I've found a thread about this issue in the archives but no solution.

When you use [pix_video] followed by [pix_movement], you get either a white frame or a black frame every once in a while.

In Windows I see black-frame flickering, while in Mac I have seesn "frame-identity" flickering. By "frame-identity flickering" I mean that pix_movement outputs an image equal to the input frame, as if the frame was compared with a black previous frame.

I guess the reason of the flickering is that the camera may generate frames slowlier than Gem renders, that is, in the time between one frame rendering and the next one, the camera may not have produced a new frame.

My guess is that that in Mac, when this happens, the "missing" frame is seen as a black frame, so pix_movement produces a difference equal to the input frame. This is clearly a bug. Pretty strange since it seems to affect only pix_movement (by directly using pix_video as a texture you don't get any black frames)....

In Windows on the other hands, it seems that when the camera has not had the time to produce a new frame, a frame identical to the last one is seen, which produces a null difference in pix_movement.

While this last case is probably the expected behaviour, it makes the combination [pix_video]+[pix_movement] totally useless to do motion detection.

How do you work this around? How can one "know" whether a new frame has been captured or not? Without this information you can't do any useful motion detection: you never know whether you are comparing two actually identical frames or the same frame.......

Any idea?

An obvious workaround is to lower gem's framerate but this is obviously unacceptable in most situations...

thanks in advance m.