How does the "verify" option work?

[berini]

A question just out of curiosity.

 

When ImgBurn is burning, you can check the "verify" checkbox. I always do.

After burning, ImgBurn will verify the disc.

 

But what does ImgBurn do when it verifies? Does it check the burned data (bit-to-bit) against the data on the HD, or does it check against a (temporary) image, or against a checksum file, or...?

 

I'm asking because when I burn a DVD video disc, ImgBurn often alters some IFO/BUP files (which actually is a good thing as I read somewhere else, but that's another story).

However, ImgBurn tells me the disc is OK after verifying. Well, the disc is OK, but it's different from the files I made ImgBurn burn to disc.

[LIGHTNING UK!]

It compares at sector level (and byte level within each sector).

 

Although it is semi aware of where certain files start/end on the disc, it doesn't work with the individual files or just compare file data between what's on the disc and what's on the hdd.

 

When using Build mode, the virtual disc image (file system + file data) is constructed on-the-fly in memory and fed to the common burning code (that burns disc images - i.e. Write mode).

 

Whatever it does to your files (in memory) during the build/burn as part of making up that virual disc image gets repeated during the verify phase.

[berini]

I understand. Interesting.

Instead of checking what's on the disc, it checks what should be on the disc.

Thanks for explaining!