CODEWITHSUNDEEP
barcodedecodingdvdcd-rom
mossymountain
mossymountain

Reputation: 183

What is the type of this barcode found on some optical discs?

The barcode is found on the clear side of some CDs and DVDs (all of them bearing "DADC", "Sony DADC" or "Sony Music" somewhere on the ring)

There are only two widths and they are always in the configuration 1,2 or 2,1. I'll treat these as binary 0 and 1 from now on.

The data seems to be aligned in four bits, with 0x0 to 0x9 representing numbers 0-9 and some sort of encoding for other characters (for example 0xb0 produces 'A' and 0xd6 produces '-').

It seems like 0xa begins a text mode sequence, 0xe begins some different mode sequence (some of it seems to be a checksum) and 0xf ends it.

a few examples in hexadecimal, with corresponding human-readable text version from the ring after whitespace:

ab00100199443d60101e8085f   A0100199443-0101
ab00100343510d60101e9880f   A0100343510-0101
ab00100993638d6b0911e29420f A0100993638-A911
ab00100993638d6b1911e29421f A0100993638-B911
ac85107702000d60101e5688f   S5107702000-0101
ac85107642000d60101e5388f   S5107642000-0101
ab00100779256d6b0511e28211f A0100779256-A511
a32d6475824d610e6094f       32-475824-10
ab00100490591d6b0511e26302f A0100490591-A511

There may be errors, I decoded them by hand.

The only example I found with the barcode visible from the label side, resulting in a clear scan (the first example): the ring before the inner TOC on the 1996 CD "Backstreet Boys" @600DPI convert XiOSq.jpg -resize 314% -distort DePolar 0 -gravity southeast -crop 53x10% +repage -resize 100x16%\! output.jpg: rectangular version of the same ring The shorter barcode, present on CDs (e6b007f in this example), is a mystery.

clean version of the first example:
clean version of the first example, ab00100199443d60101e8085f

(the 314% and 16% are just approximations of 100pi and 50/pi, to make the outer edge of the circle the same length, and the width of the ring match between the images; 53% is the percentage of the circle elapsed clockwise from the top to just after the "DADC" logo, and 10% is the percentage [from the outer edge of the circle to the middle] which I wanted to be the top of the output image; south = outer edge; east = clockwise)

Upvotes: 0

Views: 1033

Answers (2)

user7360750
user7360750

Reputation:

Apologies for necro-ing this post, but the folks over on the Redump Forums cracked this custom encoding a little while back.

The encoding is a combination of 4-bit BCD for integers and a custom hex-encoding for characters, which can be viewed in the post linked above.

I created a decoder for this encoding while trying to find the same thing, which can be found here. It's very basic and incredibly messy, but it accepts the raw binary of a barcode and outputs a decoded string.

Upvotes: 0

LupusE
LupusE

Reputation: 161

Google for 'CD Matrix'

Until now I can't see any practical use for the consumer. Most barcode reader I'm working with even can't read the round barcode (it's a nice use of convert in your post!). Maybe it is a kind of early 'genuine product' label (like the holographic pictures) to prevent music-piracy in pre-mp3 times.

Source: https://www.discogs.com/help/submission-guidelines-release-format.html#CD_Matrix https://www.discogs.com/help/submission-guidelines-release-barcode.html

Upvotes: 0

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