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At that time, printers already printed yellow dots with the serial ID. I’m most surprised VHS wasn’t watermarked. It could have helped a lot in terrorist invest

At that time, printers already printed yellow dots with the serial ID. I’m most surprised VHS wasn’t watermarked. It could have helped a lot in terrorist investigations (ransom videos). I’m always afraid when I hear someone copypasting Apple memos. Obviously they must have watermark, if not text glyphs (rn = m, and further UTF-8 incantations), at least subtly different phrasing depending on which department, or person, views it.

Trixter 5y ago
> At that time, printers already printed yellow dots with the serial ID. No schools in 1987 had color laser printers with this technology (and I doubt many businesses did either). Any students trying to do something fishy would have had to make do with, at best, 24-pin dot matrix printers with color ribbons.
dymk 5y ago
Facebook has caught leakers in the past, by modifying the whitespace in internal memos shown to employees
- sillysaurusx 5y ago
  Hmm. "Command-A shift-J in macvim if you ever need to leak a memo" is now a piece of advice. How strange.
  - jack_pp 5y ago
    If you really want to be safe translate to another language then translate back
GekkePrutser 5y ago
VHS was pretty mediocre. Any watermarking inside the signal would have been noticeable or destroyed in transmission. However it's true that the top invisible scanlines normally used for Teletext could have been used for this. My VCR did record them, I was surprised to be able to view Teletext pages at the time of recording, though they were full of distortion. It would have been possible to filter that out though. I think at the time VHS recorders were still mostly analog and would have been recognisable from their artifacts the same way a typewriter can be identified once found.
- LordDragonfang 5y ago
  A VCR isn't like most other forms of visual recording media where it takes an image and records it in some other format to be converted back to an image later, it's actually a 1-to-1 analogue recording of the broadcast signal (minus any degradation from being an analogue copy). So by design it includes any tricks they used to include metadata in the normal broadcast signal. The mechanics of how they worked are actually pretty interesting, I highly recommend Technology Connections' video on the subject [1], as well as the one on closed-captioning [2] (and his series on analogue TV in general [3]) [1] https://www.youtube.com/watch?v=KfuARMCyTvg https://www.youtube.com/watch?v=KfuARMCyTvg [2] https://www.youtube.com/watch?v=6SL6zs2bDks https://www.youtube.com/watch?v=6SL6zs2bDks [3] https://www.youtube.com/playlist?list=PLv0jwu7G_DFUGEfwEl0uWduXGcRbT7Ran https://www.youtube.com/playlist?list=PLv0jwu7G_DFUGEfwEl0uW...

Trixter 5y ago

> At that time, printers already printed yellow dots with the serial ID. No schools in 1987 had color laser printers with this technology (and I doubt many businesses did either). Any students trying to do something fishy would have had to make do with, at best, 24-pin dot matrix printers with color ribbons.

dymk 5y ago

Facebook has caught leakers in the past, by modifying the whitespace in internal memos shown to employees

sillysaurusx 5y ago
Hmm. "Command-A shift-J in macvim if you ever need to leak a memo" is now a piece of advice. How strange.
- jack_pp 5y ago
  If you really want to be safe translate to another language then translate back

GekkePrutser 5y ago

VHS was pretty mediocre. Any watermarking inside the signal would have been noticeable or destroyed in transmission. However it's true that the top invisible scanlines normally used for Teletext could have been used for this. My VCR did record them, I was surprised to be able to view Teletext pages at the time of recording, though they were full of distortion. It would have been possible to filter that out though. I think at the time VHS recorders were still mostly analog and would have been recognisable from their artifacts the same way a typewriter can be identified once found.

LordDragonfang 5y ago
A VCR isn't like most other forms of visual recording media where it takes an image and records it in some other format to be converted back to an image later, it's actually a 1-to-1 analogue recording of the broadcast signal (minus any degradation from being an analogue copy). So by design it includes any tricks they used to include metadata in the normal broadcast signal. The mechanics of how they worked are actually pretty interesting, I highly recommend Technology Connections' video on the subject [1], as well as the one on closed-captioning [2] (and his series on analogue TV in general [3]) [1] https://www.youtube.com/watch?v=KfuARMCyTvg https://www.youtube.com/watch?v=KfuARMCyTvg [2] https://www.youtube.com/watch?v=6SL6zs2bDks https://www.youtube.com/watch?v=6SL6zs2bDks [3] https://www.youtube.com/playlist?list=PLv0jwu7G_DFUGEfwEl0uWduXGcRbT7Ran https://www.youtube.com/playlist?list=PLv0jwu7G_DFUGEfwEl0uW...