android - renderscript processing previous frames

Question

renderscript is powerful to do matrix calculation,but if I want to processing the differential between current frame and previous frame.

What's the right method to do it:

1. Save previous frame in renderscript then do calculation after new frames coming in.
2. Save previous frame in java and send both frame to renderscript?

Method 2 should be functional but not sure if method 1 possible! How can I do that.

Answer 1

Method 2 should do the trick, you will need two Allocations, say aOld and aNew.

Have a look at ScriptIntrinsicBlend, especially the forEachSubtract - method.