Windows – What does Verify disc after burning actually do to verify the data

burningoptical-drivewindows 7

I imagine it is some kind of comparison between the original files and the files that have been burned on the disc, but does anybody know how it is really done at a low level?

I mean, does it create a hash of the source and destination content and then compares them? If it is so, does it store the hash of the burned content in RAM? Or does it save it in a temporary file on the hard drive? Is there a log file of what is going on?

Just curious to know exactly how this feature works 🙂 And I am referring to Windows Image Burner.

Best Answer

Check out these MSDN pages on windows API for the IBurnVerification interface, and the IMAPI_BURN_VERIFICATION_LEVEL enum.

For data disks, it looks like in quick mode it doesn't checksum the entire disk, just a selection of sectors. It then makes sure that the API calls READ_DISC_INFO and READ_TRACK_INFO succeed against the new disk.

For full verification, it performs the above checks, and then does a full checksum on the last session on the new disk, against a checksum computed on the memory stream being burned. The checksums have to be stored in ram, but they are likely short lived values. Note that the comparison is against the disk image in RAM, not the source media itself, so if the source data did not read correctly, it will be written incorrectly. Verification will not detect this.

For music disks, it focuses on checking READ_TRACK_INFO and the disk Table of Contents, but does not perform a Checksum calculation. There is no full verification mode for music.

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