Modifying a Disc Image
Modifying a Disc Image
Why is it when I modify a cd-i disc image with a hex editor, that disc refuses to work anymore? Even if I modify the image by just one byte, the disc simply cannot be read! Any ideas?
It's like 1993 all over again!
- cdifan
- CD-i Emulator Author
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It might depend on what you modify...
There is error-detection (EDC) and -correction (ECC) data in the disc image, but most (I'm tempted to say all) CD-i players aren't supposed to use this data unless they get error signals from the CD-drive; the primary reason for this is that error detection/correction is done in software and thus expensive performancewise. Or so the Philips technical notes say...
OTOH, they *might* do EDC in hardware; I don't really know. There are tools that reconstruct the EDC/ECC bytes after editing; the "cdedit" program which used to come with the "master" program is one such.
There is error-detection (EDC) and -correction (ECC) data in the disc image, but most (I'm tempted to say all) CD-i players aren't supposed to use this data unless they get error signals from the CD-drive; the primary reason for this is that error detection/correction is done in software and thus expensive performancewise. Or so the Philips technical notes say...
OTOH, they *might* do EDC in hardware; I don't really know. There are tools that reconstruct the EDC/ECC bytes after editing; the "cdedit" program which used to come with the "master" program is one such.
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- Karmic Church Disciple
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- Karmic Church Disciple
- Posts: 240
- Joined: Mon Feb 20, 2006 2:39 pm
- Location: Germany
- Contact: