Of course, but.
I have provided something without claiming it to be correct, on purpose; because I am here to evoke memories and joyful moments from my childhood, not ‘just’ to leave an historical and accurate testimony for future generations; although that does interest me to a certain extent, it is not that much.
Also, never forget that your eyes act like a camera and your brain acts as a -possibly lossy compressed- memory for that footage.
If something tricks my and other brains in thinking what they see is the same as it was, then I accomplished that goal; if someone say that it remembers it to be a bit different, then we can add a parameter to accomodate that too.
If someone does not remember ANY glitch at all, disable it.
Bars were not present? You sure? Well! There is a parameter to morph them or to fade them till the void.
That said, we can discuss about the correctness of the result too, why not.
the “bars” are an aproximation of the real phenomen, which is the image content vertically shrinking, while still shacking and twisting very fast.
The afterglow effect may contribute to smooth out that by turning that very fast movement into something more solid, your -not perfect- eyes can contribute to that too.
Image should be NEVER displayed alongside the bars, because the image itself morphs into a bar, but on a real crt, all that happens so fast that is impossible to replicate on a mere 60h or, worse, 30fps running shader (the shader runs at core refresh).
All we can do is to imagine that those very fast glitch can be time compressed into a bar appearing “in the same frames” as the image.
Check this from real fresh footage just done by me, 900+fps, see the afterglow, see the image shrinked at bar size at second #12, then suddenly the synced image.
https://mega.nz/file/kX9znJQb#Mvpx9mjWNUvgk58RfVam80EChw85UM2gghKN27aNNLc
At 60fps the image kinda morphs into a noise:
https://mega.nz/file/pOsnWSCR#BDE8nbFUs102jEBN5LS1rtW64fkTC_Z1QxUWjT5G48s
This is upside down, sorry
https://mega.nz/file/8fECQKLJ#b6JwdQz7qclBgHR-11UZYbCiwonsheSX536W_5f0MeY
Those videos explain what the bar is for; where it should be placed seem to vary greatly from circuit to circuit (or even on the same circuit, from switch to switch) due to probably too much obscure things that i like to call randomness, so we paint them at image borders and give the user the ability to shake the image more, so that the bars would appear more or less centered.