MVTools

The MVTools package contains a collection of functions for estimation and compensation of objects motion in video clips. Motion compensation may be used for strong temporal denoising, advanced framerate conversions, image restoration and other tasks.

The plugin contains the motion estimation server-function MVAnalyse to find the motion vectors and several motion compensation client-functions (MVCompensate, MVMask and others) which use these vectors.

Plugin uses block-matching method of motion estimation (similar methods are used in MPEG2, MPEG4, etc). At analysis stage plugin divides frames by small blocks and try to find for every block in current frame the most similar (matching) block in second frame (previous or next). The relative shift of these blocks is motion vector.   The main measure of block similarity is sum of absolute differences (SAD) of all pixels of these two blocks compared. SAD is a value which says how good the motion estimation was.

The output of MVAnalyse (server) is special clip with motion vector information in some format. At compensation stage the plugin client functions read the motion vectors and use them to move blocks and form motion compensated frame (or realize some other full or partial motion compensation or interpolation function).

Every object (block) in this (fully) compensated frame is placed in the same position as this object in current frame. We may (for example) use strong temporal denoising even for quite fast moving objects without producing annoying artefactes and ghosting (object's features and edges are coincide if compensation is perfect).   Plugin can create compensated neighbor frames for every current frame, and denoise it by internal function. Alternatively, you can use compensated and original frames to create interleaved clip, denoise it by any external temporal filter, and select central cleaned original frames for output (see examples).

Of course, the motion estimation and compensation is not ideal and precise. In some complex cases (video with fading, ultra-fast motion, or periodic structures) the motion estimation may be completely wrong, and compensated frame will be blocky and (or) ugly. Severe difficulty is also due to objects mutual screening (occlusion) or reverse opening.

Complex Avisynth scripts with many motion compensation functions may eat huge amount of memory and result in very slow processing. It is not simple but quite advanced plugin. Use it for appropriate cases only, and try tune its parameters. There are many discussions about motion compensation using at doom9 Avisynth forum. In particular see old MVTools thread, true motion thread, new MVTools thread and some other. Try read postings in addition to this documentation and ask for support there.