# Generate video motion vectors, in various colours, and merge together
# NB: Includes fixed 'curve' filters for issue outlined in blog post
ffplay \
-flags2 +export_mvs \
-i video.mkv \
-vf \
"
split=3 [original][original1][vectors];
[vectors] codecview=mv=pf+bf+bb [vectors];
[vectors][original] blend=all_mode=difference128,
eq=contrast=7:brightness=-0.3,
split=3 [yellow][pink][black];
[yellow] curves=r='0/0 0.1/0.5 1/1':
g='0/0 0.1/0.5 1/1':
b='0/0 0.4/0.5 1/1' [yellow];
[pink] curves=r='0/0 0.1/0.5 1/1':
g='0/0 0.1/0.3 1/1':
b='0/0 0.1/0.3 1/1' [pink];
[original1][yellow] blend=all_expr=if(gt(X\,Y*(W/H))\,A\,B) [yellorig];
[pink][black] blend=all_expr=if(gt(X\,Y*(W/H))\,A\,B) [pinkblack];
[pinkblack][yellorig]blend=all_expr=if(gt(X\,W-Y*(W/H))\,A\,B)
"
# Process:
# 1: Three copies of input video are made
# 2: Motion vectors are applied to one stream
# 3: The result of #2 is 'difference128' blended with an original video stream
# The brightness and contrast are adjusted to improve clarity
# Three copies of this vectors result are made
# 4: Curves are applied to one vectors stream to create yellow colour
# 5: Curves are applied to another vectors stream to create pink colour
# 6: Original video stream and yellow vectors are combined diagonally
# 7: Pink vectors stream and original vectors stream are combined diagonally
# 8: The results of #6 and #7 are combined diagonally (opposite direction)
NB: At time of writing, the latest version of FFmpeg (N-81396-g0d8b6a1) has a bug (feature?) where upper and lower bounds of 'curves' filter must be set for accurate results. This is contrary to what's written in official documentation.
alternate version:
see related: http://oioiiooixiii.blogspot.com/2016/04/ffmpeg-display-and-isolate-macroblock.html
source video: 足太ぺんた (Asibuto Penta) https://www.youtube.com/watch?v=Djdm7NaQheU
