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Premastering Metadata

Checksums for DDP

Whenever you use an insecure or uncertain transport medium for digital files, whether it's the internet or a writable optical disc, you never know when your data may be corrupted. A quick and easy solution to this problem is to generate a checksum for your precious files. Often used as a way of verifying the integrity or authenticity of a file copy, a checksum is a sort of digital “fingerprint” that, when read and compared to a known good example, can inform you of errors or tampering during transport.

Using the Terminal’s MD5 feature

Mac OS 10’s command line interface, the Terminal, includes an MD5 checksum implementation. As the man page says, “MD5 takes as input a message of arbitrary length and produces as output a
128-bit “fingerprint” or “message digest” of the input. It is conjectured that it is computationally infeasible to produce two messages having the same message digest, or to produce any message having a given prespecified target message digest. The MD5 algorithm is intended for digital signature applications, where a large file must be “compressed”
in a secure manner…”

To use the Terminal’s MD5 function, first ZIP the entire folder containing your DDP file set by control or right–clicking on the folder and selecting Finder’s Create Archive of… option. Rename the file so it has only a “.zip” extension. Then, launch Terminal and type “md5 ” at the prompt. Note the space after "md5”…Then, drag and drop the ZIP file onto the Terminal window and hit the return key. If you did things correctly, you should see something like:

MD5 (/Volumes/ExplicitPath/DDP.zip) = checksum

where ExplicitPath is the path to the ZIP’d DDP file and checksum is a very long string of numbers and letters.

Copy that resulting checksum string, paste it into a plain text file, and save that file with the name “CHECKSUM.txt” — making sure before hand that the file is a plain text, ASCII file. Send both the CHECKSUM.txt file and the ZIP'd DDP file set to your replication plant.

For a graphical UI version of the Terminal’s MD5 function, see md5app in the Free & Useful Utilities section of our Downloads page.

ISR Codes (ISRC)

ISR Codes are controlled by the IFPI.

UPC/EAN

UPC/EAN codes are controlled by the GS1, formerly the Uniform Code Council.