Face detection for record sleeves

I have been digging a bit into image processing in the last few weeks using OpenCV. OpenCV is very powerful and comes with lots of built-in goodies, such as a face detector. So, I was thinking: what can I do with that? How easy is it to detect sleeves that have people's faces on it? As it turns out: trivial. I grabbed my copy of Practical Python and OpenCV and followed chapter 14. I then downloaded an image and fed it to my code:

Not perfect as only three out of four faces get recognized, probably due to a limitation in the classifier but not bad at all for less than 50 lines of Python code.

Another example:

So, why is this useful?

Let's make this a bit more concrete with another example. Some users collect sleeves with a certain theme. One possible theme could be cats. At least one user at Discogs has a list with sleeves that have cats on them. And, believe it or not, OpenCV also has a built-in cat classifier (for frontal cat faces only), so I used that on one of the sleeves:

If I could just search on things like "cat", "flower" or "banana" and get the releases that I would want to see then Discogs would be a lot more useful for people that don't collect releases of a certain artist, but collect based on a certain theme. Right now none of this data is available in Discogs.

There is a lot of potential with the data in Discogs, but at the moment it is simply untapped, and that's a bit of a shame.

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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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