A Stack Overflow user discovered that you can sniff the request that your phone makes when scanning the barcode to determine the media reference and API endpoint. After extracting a media reference from a barcode, you check with Spotify’s database (a look-up table) to determine what URI it corresponds to. The media reference may just be the hash of an incrementing index. This media reference is 37 bits long and is the key that links a barcode to a given URI. When you visit Spotify codes and input a Spotify URI, a “media reference” is created by Spotify.
SPOTIFY CODE SCANNER FULL
I used to think academic papers were full of jargon until I read some technical patents. This question was a start, but I ended up asking this SO question and getting a couple of answers that linked to the relevant patents and contained more info about Spotify’s look up table. This is when I started asking questions and hunting for answers. How do you convert a 63^22 bit URI into an 8^20 bit barcode? There is 2.3e+21 times as much information in the URI than there is in the barcode. This means that there are 8^20 pieces of information that can be encoded into the code. The barcode consists of 23 bars, of which only 20 actually contain information. This is the sequence of the “Take On Me” Spotify code: # multiply by 8 to get an octal integer ratio *= 8 ratio //= 1 # convert to integer (and make 0 based) sequence. # the first object (spotify logo) is the max height of the bars logo = bar_dimensions # get the dimensions and positions of bounding box around objects bar_dimensions = # label connected regions as objects labeled = label(binary_im) """ # convert to grayscale, then binary image = io. """Open an image and return a list of the bar heights. In this function I use scikit-image to calculate the sequence of bar heights from a logo.įrom asure import label, regionpropsįrom skimage.filters import threshold_otsu This makes it easy to generate ratios of the bars’ heights. The Spotify logo’s diameter is the same as the height of the highest bar. When the bars are sorted by height you can see that there are 8 discrete heights that they fall into.
This is the Spotify code for the ABBA song “Take a Chance on Me”: Information can be stored in the bars by setting them to different heights. Spotify codes work like the Intelligent Mail Barcode. QR codes use a 2d matrix of dots to encode data.Ī lot of mail barcodes encode data using the height of the bars (like the Intelligent Mail barcode). Universal product codes (UPCs) encode 12 digits using combinations of vertical bars of different widths:Īnother barcode uses colors to encode data: Information is encoded into different barcodes in a variety of ways.Ī lot of barcodes encode data in the widths of vertical bars. The history of barcodes is quite extensive. Safe to say Spotify is not going to run out of URIs anytime soon. If Spotify printed a whole Bible’s worth of URIs every millisecond they could do this for 85,863,890,404,701,306,452,633 years. X = 62 ** 22 # the number of milliseconds in a year x //= 365 * 24 * 60 * 60 * 1000 # the number of words in the bible (about 1 million) x //= 1000000
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