Fixing wrong credits in Discogs (part 1)

For releases in Discogs it is customary that people add the credits for a release, like who wrote songs, produced the record, mastered the recording, and so on. In some cases this information can be important, as some reissues or versions of records have been mastered by different people (I don't have an example, but I remember bumping into this while browsing through releases).

Discogs has published a list of credits and roles that can be used in the database. These are the only ones that should be used and when editing a release that has a different role an error saying that something "does not match the credit list" (or similar to that) will be shown and you are expected to fix it first. Since a friend saw this error very frequently it got me wondering how many releases in Discogs there are with a credit that is not on the official credit list.

For my clean up scripts I created a script to extract the credits list (so I wouldn't need to hardcode it), added a few checks for incorrect credits and processed the latest data dump. The results: 121,010 incorrect credit roles were found in 52,957 releases.

Distribution of incorrect credit roles over releases in the Discogs database

It is clear that especially for older releases there are many wrong roles. Looking at the data it seems that the credit role error checking only came into effect around release number 10,533,000. This would explain the fact that the last bar in the chart is only about half of the size of the second to last bar. The sharp decrease around release 4,000,000 suggests that something happened there as well, but it is not immediately clear and likely will involve digging through the Discogs forums or technical release notes.

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SID codes (part 1)

One thing that I only learned about after using Discogs is the so called Source Identification Code, or SID. These codes were introduced in 1994 to combat piracy and to find out on which machines a CD was made. It was introduced by Philips and adopted by IFPI, and specifications are publicly available which clearly describe the two available SID codes (mastering SID code and mould SID code). Since quite a few months Discogs has two fields available in the " Barcode and Other Identifiers " (BaOI) section: Mould SID code Mastering SID code A few questions immediately popped up in my mind: how many releases don't have a SID field defined when there should be (for example, the free text field indicates it is a SID field)? how many releases have a SID field with values that should not be in the SID field? how many release have a SID field, but a wrong year (as SID codes were only introduced in 1994) how many vinyl releases have a SID code defined (which is impossi...

SPARS codes (part 1)

Let's talk about SPARS codes used on CDs (or CD-like formats). You have most likely seen it used, but maybe don't know its name. The SPARS code is a three letter code indicating if recording, mixing and mastering were analogue or digital. For example they could look like the ones below. There is not a fixed format, so there are other variants as well. Personally I am not paying too much attention to these codes (I simply do not care), but in the classical music world if something was labeled as DDD (so everything digital) companies could ask premium prices. That makes it interesting information to mine and unlock, which is something that Discogs does not allow people to do when searching (yet!) even though it could be a helpful filter. I wanted to see if it can be used as an identifier to tell releases apart (are there similar releases where the only difference is the SPARS code?). SPARS code in Discogs Since a few months SPARS is a separate field in the Discogs ...

Using matrix numbers of CDs to verify release years (1)

One of the first steps when making CDs is to produce a "glass master". From that (using a few more steps) a "stamper" is created which is then used to press the actual CDs. When looking at a CD you can often see text in a ring in the middle of the CD. This is the so called matrix which comes from the glass master. Apart from the matrix other text (like the IFPI mastering SID code) could possibly also come from the glass master. A bit of background information can be found on page 7 of the IFPI SID code implementation guide although I would also highly recommend watching some of the clips about glass masters on YouTube, which are highly informative. One company making a lot of these glass masters is Cinram . For most of their glass masters they stored the production date in matrix. This is good news, because it means that it could possibly be used to verify releases and see if the declared year of the release is right: it could never have been released before...

Vinyl & Data

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