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Adventures in fingerprinting

Filed under: DAD,Fedora,GStreamer — Thomas @ 8:55 pm

2011-8-9
8:55 pm

One of the key concepts in my rewrite of DAD is that it should be possible to relate the same track across different files and computers. I have copies of files, and different encodings of the same track, spread across machines. Various applications I use for playback seem to exist in isolation on each machine, and so I tend to rate only occasionally knowing that my ratings aren’t centralized. And I get annoyed when banshee detects three copies of an album, and then orders them by track number, playing each track three times before moving on to the next one.

The logical way to do is is through acoustic fingerprinting. These are algorithms that extract certain features from an audio file and calculate an algorithm-specific ‘fingerprint’ for it. Usually, these fingerprints are not identical across different encodings of the same file, so you can’t look up twins in a list; but the fingerprints can be compared to each other and a ‘difference’ within a certain confidence interval calculated.

Most fingerprinting algorithms have a library that calculates a fingerprint and then submits it to a complimentary web service where it can quickly compare it to find twins.

In the past, either the client library/application or the web service (or both) was not open enough to be of interest for most Free Software people.

But recently, someone in the #morituri channel mentioned acoustid which only consists of open components. So, that seemed interesting enough to try out!

The chromaprint client-side library consists of a library, a sample application (linked against FFMPEG), and a python module with some sample scripts.

There is also a gst-chromaprint GStreamer plug-in on github. (As a side note, amazing to see that GStreamer plug-ins these days come for free! I recall the days when we had to the work ourselves to write GStreamer plug-ins for libraries)

So, after giving them a quick test run, I packaged up the whole set and it’s now available for Fedora 14 and 15 in my package repositories

The chromaprint-tools package contains fpcalc and you need to enable rpmfusion-nonfree to get its ffmpeg dependency.

And after that, I created a Task in DAD for chromaprint, and now I have:

$ dad analyze chromaprint /opt/davedina/audio/albums/Afghan\ Whigs\ -\ Gentlemen/Afghan\ Whigs\ -\ Debonair.ogg
** Message: pygobject_register_sinkfunc is deprecated (GstObject)
/opt/davedina/audio/albums/Afghan Whigs - Gentlemen/Afghan Whigs - Debonair.ogg:
Found 1 results
- Found 4 recordings.
- musicbrainz id: 62b2952a-4605-4793-8b79-9f9745ea5da5
- artist: The Afghan Whigs
- title: Debonair
- musicbrainz id: 8ff78e73-f8bd-4d78-b562-c3e939fb93fb
- artist: The Afghan Whigs
- title: Debonair
- musicbrainz id: a0d5ced6-43e8-450a-bf11-94f1f4520b92
- artist: The Afghan Whigs
- title: Debonair
- musicbrainz id: d01ac720-874c-48d6-95c6-a2cb66f9d5d0
- artist: The Afghan Whigs
- title: Debonair

Sweet…

Now it’s time to dump that in the couchdb database backend, and start identifying duplicate tracks.

Acoustid seems to be a relatively young project, but its maintainer is very active on the mailing list and it’s filling a hole in the open world that I’m happy to see filled! Thank you Lukas.

2 Comments »

  1. Have you looked at the fingerprinting techniques that apps like shazam use? They can identify a song by a recording in noisy conditions. The basic algorithm works actually quite easy.

    http://laplacian.wordpress.com/2009/01/10/how-shazam-works/
    http://labrosa.ee.columbia.edu/matlab/fingerprint/

    Comment by Olivier Sessink — 2011-8-10 @ 8:46 am

  2. Shazam is closed. The links you posted look interesting, maybe someone implemented it in open source code.

    Something like Shazam is not directly what I want. I want to identify tracks that are the same recording, and afaict Shazam does more coarse-grained matching, and can match for example live versions too, or humming.

    Comment by Thomas — 2011-8-10 @ 11:26 am

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