qctools field-split waveform second draft

This video uses the ffmpeg histogram filter to generate two waveform images, one for the odd lines of a video and another for the even. In this instance the waveform images demonstrate a head clog occurring in the video deck when the source tape was digitized. The head clog becomes predominant starting around 00:17 where head 1 fails to read properly causing significant visual discrepancies of the visual information relayed between head 1 and head 2 of the video deck's head drum.
This can be replicated using ffmpeg's filterchain like this:
ffplay yourfilehere.mov -vf 'split[a][b];[a]field=top[c];[b]field=bottom[d];[c]histogram=step=16:mode=waveform:waveform_mode=column:waveform_mirror=1,crop=iw:256:0:0,drawgrid=y=(256-16):c=white@0.4,drawgrid=y=(256-235):c=white@0.4,drawbox=y=(256-16):w=iw:h=16:color=aqua@0.2:t=16,drawbox=w=iw:h=(256-235):color=crimson@0.2:t=16[e];[d]histogram=step=16:mode=waveform:waveform_mode=column:waveform_mirror=1,crop=iw:256:0:0,drawgrid=y=(256-16):c=white@0.4,drawgrid=y=(256-235):c=white@0.4,drawbox=y=(256-16):w=iw:h=16:color=aqua@0.2:t=16,drawbox=w=iw:h=(256-235):color=crimson@0.2:t=16[f];[e]pad=0:ih*2[g];[g][f]overlay=0:h'