Disc Image Quality at DVinfo.net

Dave Perry · August 24th, 2005, 06:30 AM

My understanding of a disc image is that it is a copy of a disc and will remain in tact just as a physical disc will. The reason I post this message is because my boss thinks that the disc image we have saved of our demo reel, recently started losing quality and having interlacing problems when burned to DVD. Is this possible? I think he is just noticing artifacts and other things that he didn't notice before.

We archive all of our DVD SP 3 projects for clients this way. If a disc image can lose quality (which I think impossible) we need to archive in a different way.

TIA, Dave

Mark Sloan · August 24th, 2005, 05:03 PM

If the disc image is saved on a Hard Drive, the likelyhood of it causing the video quality to degrade is minimal. But it is "technically" possible to lose bits of data over time as blocks on the Hard Drive go bad. But it most likely would be so minimal and so spaced out that it wouldn't be visible, you would have to be having a major Hard Drive failure.

If the disc image is saved on a DVD-ROM, then it is much more likely that parts of the data are being lost or that the disc has become scratched.

In the end, you are probably right, and simply having watched it so many times your boss is now noticing the artifacts.

Boyd Ostroff · August 24th, 2005, 05:20 PM

The only explanation I can think of is that you are somehow recompressing the data and losing quality that way. I doubt that's happening if an image of the data is just getting copied to the DVD, but I don't know much about how DVD burning software works.

August 24th, 2005, 06:30 AM	#1
Dave Perry Major Player Join Date: Mar 2004 Location: Roanoke, VA Posts: 796	Disc Image Quality My understanding of a disc image is that it is a copy of a disc and will remain in tact just as a physical disc will. The reason I post this message is because my boss thinks that the disc image we have saved of our demo reel, recently started losing quality and having interlacing problems when burned to DVD. Is this possible? I think he is just noticing artifacts and other things that he didn't notice before. We archive all of our DVD SP 3 projects for clients this way. If a disc image can lose quality (which I think impossible) we need to archive in a different way. TIA, Dave __________________ Dave Perry Cinematographer LLC Director of Photography • Editor • Digital Film Production • 540.915.2752 • daveperry.net

August 24th, 2005, 05:03 PM	#2
Mark Sloan Major Player Join Date: Jun 2002 Location: Venice, CA Posts: 346	If the disc image is saved on a Hard Drive, the likelyhood of it causing the video quality to degrade is minimal. But it is "technically" possible to lose bits of data over time as blocks on the Hard Drive go bad. But it most likely would be so minimal and so spaced out that it wouldn't be visible, you would have to be having a major Hard Drive failure. If the disc image is saved on a DVD-ROM, then it is much more likely that parts of the data are being lost or that the disc has become scratched. In the end, you are probably right, and simply having watched it so many times your boss is now noticing the artifacts.

August 24th, 2005, 05:20 PM	#3
Boyd Ostroff Wrangler Join Date: Dec 2002 Location: Mays Landing, NJ Posts: 11,797	The only explanation I can think of is that you are somehow recompressing the data and losing quality that way. I doubt that's happening if an image of the data is just getting copied to the DVD, but I don't know much about how DVD burning software works.