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DVD screen caps...
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Grizzled Veteran
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Feb 2, 2000, 09:27 AM
 
A student of mine feels it necessary to take soem screen captures from various DVD's for a project...not entirely surprisingly, when he opens the file all that he gets is a green rectangle. HOWEVER, oddly enough, he CAN open the PICT in Illustrator AS LONG AS the DVD is in the drive...any idears? thanks...
     
lombardman
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Feb 3, 2000, 11:00 AM
 
Present the video full screen then pause where you need the shot. Use the key combo shift-command-3 to take a screen shot. I just tried it with the Matrix and it worked great.

[This message has been edited by lombardman (edited 02-03-2000).]
     
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Feb 3, 2000, 12:43 PM
 
No, it didn't work.

Remove the DVD and try viewing the image again.

DVDs and their software are designed to protect the copyright of the movie producers.
What is catpured in a screen shot of a DVD image is a place holder to that frame on the disk. The image will appear while the disk is in the drive, but remove the DVD, and all you get is a blank square. This isn't a bug or a technical shortcoming, it is designed into the system to prevent copying of DVD material (being digital, copies do not suffer degeneration, as analog formats do).

There was a controversy a couple of weeks ago when someone released a hack to allow DVD images (or more to the point, entire movies) to be decoded and captured. Already a court has ordered this stopped.

The only solution that comes to mind is to use a traditional Analog to Digital capture device. Play the DVD into a capture card (there are a number of them out there, ATI's Xclaim VR, for instance), and capture the stills that way. Not very elegant, I know, but it's the only game in town, as far as I know...


Tod Abbott.
     
Russ Laeufer
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Feb 3, 2000, 12:47 PM
 
About this DVD screen capture thing. Forget it. Once you remove the DVD from the computer and you try to open your captured screen snap you just get a blank capture. I have been using Screen Snap Pro and they had said that they would incorporate DVD screen capture in the next version. (that was 2 versions ago) It would seem that if the DVD screen was displayed on the screen a program would be able to capture i in the video ram buffer. But DVD is a different situation. Nost likely because of the DVD copy protection/encoding. I don't even know that if you were to record the composite out of a DVD player into a DVD VCR and play that back into a Firewire capable Mac and then try to edit it Final Cut Pro. Maybe then you could capture the image... I will try this later this year as I'm setting up a DV editing studio now.
     
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Feb 3, 2000, 12:57 PM
 
CMYKid: the reason your friends is getting a green rectangle is because he is using Apple's hardware decoder, which totally separates the DVD image from the video RAM, which is what command-shift-3 (or 4) copies. The DVD decoder simply fills any green pixels in the masking area (i.e. the size the decoder has been told the viewing window is) with the DVD image. I know of no way of getting around this on my B&W G3. You could try using a software decoder, such as a hacked copy of Apple DVD Player 2.0, as those draw to video RAM.

Lombardman: what computer are you using? (presumably an AGP G4 or iMac DV?)

gtabbot: I don't think it was done because of copyright issues, it is a technical limitation of how discrete hardware DVD decoders work (if the DVD decoder is a part of the graphics chip, which is not the case in Apple's systems, then presumably screen captures would work). Admittedly, it's a limitation I don't think the studios mind ;-)

tooki
     
fish
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Feb 3, 2000, 01:14 PM
 
The DVD software is such that the images are never actually going through the video card on the computer, only the MPEG2 decoder. This is why you get a green screen. When you watch the DVD, it is actually being shown on a green screen. There is one cool thing you can do with this however. Take the screen capture with the green screen, and make it the desktop background image. Then when you play any DVD, the video will appear on the desktop.

Originally posted by CMYKid:
A student of mine feels it necessary to take soem screen captures from various DVD's for a project...not entirely surprisingly, when he opens the file all that he gets is a green rectangle. HOWEVER, oddly enough, he CAN open the PICT in Illustrator AS LONG AS the DVD is in the drive...any idears? thanks...
     
Mark Daniel
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Feb 3, 2000, 01:27 PM
 
The green screen is indeed for copy protection. I believe this is what's happening: the DVD player (apple dvd player, etc) is doing 3 very basic things - telling the DVD decoder (either in hardware or software) to play the DVD signal at a certain coordinate on the screen at a particular size, displaying a big green box at that coordinate and at that size, and allowing the DVD decoder to overlay a particular color in the video controller's CLUT with the DVD decoders signal (this color being the exact green that you see in your screenshots). Give this a shot: open your dvd player and hit play. Hide the DVD player. Go into photoshop and create a document with as many shades of green close the green used by the DVD software in the document (using a gradient or clouds or something). You should see the DVD playing through the document window wherever that particular green occurs in the document. What this means is that to get a screen capture, the capturing software would have to have it's own decoding software built into it, or find a way to gain access to Apple's DVD decoding software.
     
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Feb 3, 2000, 03:04 PM
 
Also don't forget about Macrovision. Most studio discs feature this analog copy protection, which might prevent you from outputing the signal from the Mac to a VCR or other video capture box.

-jess
     
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Feb 3, 2000, 04:41 PM
 
CMYKid,

You said that you can open the PICT in Illustrator right? Have you tried taking another snap shot of pict in illustrator?
In other words open the pict with illustrator and then take a pict with the shortcut keys.

:::::::never mind I just tried it, didn't work::::::::

[This message has been edited by disectamac (edited 02-03-2000).]
     
Joel Amar
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Feb 4, 2000, 03:38 AM
 
I think that this subject was already discussed about a year ago with the introduction of DVD Player, and everybody arrived to the conclusion that command-shift-3,4 didn't work but with SnapzPro (a utility from Ambrosia that takes pictures from your screen) there was no problem.

Joel Amar
     
JiveTurkey
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Feb 4, 2000, 04:31 AM
 
Regardless of anything else, the video signal MUST pass through VRAM before it is written to the screen. If someone could write a hack to dump the entire contents of VRAM to a file and then sift through the raw data for the screen image we would have a working DVD screen capture utility...
     
BillR
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Feb 4, 2000, 08:29 AM
 
The Apple DVD player simply sets up a screen for the video to be played on. The actual video stream is then sent through a different hardware circuit to the video out. As a result, video capture programs can't capture anything from the stream as it doesn't get passed through the V-RAM. Not even Snapz-Pro, as versatile as it is, can capture this stream.

A friend of mine got around this by conecting an external DVD player to his Mac via a digital splitter. With this, he can capture the images he needs.

I realize that all this is a pain in the neck for people who would like to have screen captures of films and stars they are fans of. But remember that DVD's are new, and the movie industry is reacting to them the same way the recording industry did to CD's. In a couple of years when they see they aren't losing money, the restrictions will be loosened.

In the end, when this happens, please remember to respect the living the artists try to make from their work. If they are making money from it, they will make more for you to enjoy.
     
CMYKid  (op)
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Feb 4, 2000, 09:17 AM
 
t'anks for the info...i was pretty sure that it wasnt so much a copy-protection issue as it was a hardware issue, i just didn't quite realize to what extent the image actually WAS separated from the video signal to the screen. It's vaguely interesting that you CAN open the PICT only in Illustrator, and it still links to the DVD drive...maybe it can be exported to another format that way...hmmm

thanks for all of the info...
     
   
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