x-ray - without knowing gory details, I can’t tell you why your old player won’t play certain discs - DVD’s use both Macrovision and CSS encryption - but those both require ADDITIONAL circuits - so I’d guess there was a spec change in DVDs thay the old player couldn’t handle. If you got no usable signal, it was that the hardware didn’t know how to read the data. If you got clear/garbage/clear, it was some kind of encryption.
All - the Macrovision (AND CSS) signals require active circuitry in the player to recognize - thus, the early VCRs do NOT recognize Macrovision, and do not know to scramble the video gain.
And, of course, there is/was the notorious Chinese DVD player with the hidden menu to disable either or both macrovision and CSS - they were quickly pressured to remove that menu.
It is now to the point where the studios and the pirates are playing cat-and-mouse - both Macrovision and CSS can be (reasonably) easily hacked, to the race is on - but please, studios - THINK your schemes through - allowing your shiny new plan to be defeated by either a felt-tip pen and/or the “shift” key is downright embarrassing…
- ex, who has nothing but the highest regard for the DMCA