Why can't a decrypted video be recorded from the monitor

[Andre123]

Obviously I'm just a novice but I would like to know why a decrypted video can't be recorded from the monitor signal since it must be decrypted at that point to be clear and visible. I've tried to find the answer on Google but was unsucessful. It must be a simple but I don't know it.

[jggimi]

I'm not sure what you're trying to accomplish, so this answer may or may not help you. If you provided more information, you might get a better answer. There are multiple encryptions on commecial DVDs. CSS is used for digital encryption of the .VOBs, but MacroVision (an analog copy prevention schema) is commonly used on the video stream. For more information, see Question 1.11 of The Official DVD FAQ (http://www.dvddemystified.com/dvdfaq.html).

[Andre123]

What I'm trying to do is educate myself about DVDs. I've successfully made copies of DVDs I own using several of the programs mentioned in the forum but I was wondering why it was necessary to go through all that trouble when apparently the signal to the monitor has to be already decrypted to be viewed correctly. In other words I'm tryimg to find out for my own understanding of the process of encryption and decryption. The link you gave me seems very useful but I'll have to think about it for awhile.
Thank you for your assistance.

[r6d2]

Originally posted by Andre123
I was wondering why it was necessary to go through all that trouble when apparently the signal to the monitor has to be already decrypted to be viewed correctly.
There is a very good reason to go into all that trouble.

If you intend to record from the PC monitor, the signal you are seeing is indeed digital, but to archive it would require a lot of space. Typically about 90-GB per movie (just the video). You can compress it, of course, but guess what... That is called encoding, which is what those tools you use are actually doing! ;)

If you intend to record from the TV, the signal you are seeing is analog, so it must be digitized, which requires a capture device and it is of much lower quality than the actual digital video ripped directly from the DVD.

Hope this clears it up for you a little.

[Andre123]

Thanks to all who replied. It cleared things up in my mind.