halting problem :: Amberol

:: ~8 min read

In the beginning…

In 1997, I downloaded my first MP3 file. It was linked on a website, and all I had was a 56k modem, so it took me ages to download the nearly 4 megabytes of 128 kbit/s music goodness. Before that file magically appeared on my hard drive, if we exclude a brief dalliance with MOD files, the only music I had on my computer came either in MIDI or in WAV format.

In the nearly 25 years passed since that seminal moment, my music collection has steadily increased in size — to the point that I cannot comfortably keep it in my laptop’s internal storage without cutting into the available space for other stuff and without taking ages when copying it to new machines; and if I had to upload it to a cloud service, I’d end up paying monthly storage fees that would definitely not make me happy. Plus, I like being able to listen to my music without having a network connection — say, when I’m travelling. For these reasons, I have my music collection on a dedicated USB3 drive and on various 128 GB SD cards that I use when travelling, to avoid bumping around a spinning rust drive.

In order to listen to that first MP3 file, I also had to download a music player, and back in 1997 there was this little software called Winamp, which apparently really whipped the llama’s ass. Around that same time I was also dual-booting between Windows and Linux, and, obviously, Linux had its own Winamp clone called x11amp. This means that, since late 1997, I’ve also tested more or less all mainstream, GTK-based Linux music players—xmms, beep, xmms2, Rhythmbox, Muine, Banshee, Lollypop, GNOME Music—and various less mainstream/non-GTK ones—shout out to ma boi mpg123. I also used iTunes on macOS and Windows, but I don’t speak of that.

Turns out that, with the very special exception of Muine, I can’t stand any of them. They are all fairly inefficient when it comes to managing my music collection; or they are barely maintained; or (but, most often, and) they are just iTunes clones—as if cloning iTunes was a worthy goal for anything remotely connected to music, computing, or even human progress in general.

I did enjoy using Banshee, up to a point; it wasn’t overly offensive to my eyes and pointing devices, and had the advantage of being able to minimise its UI without getting in the way. It just bitrotted with the rest of the GNOME 2 platform even before GNOME bumped major version, and it still wasn’t as good as Muine.

A detour: managing a music collection

I’d like to preface this detour with a disclaimer: I am not talking about specific applications; specific technologies/libraries; or specific platforms. Any resemblance to real projects, existing or abandoned, is purely coincidental. Seriously.

Most music management software is, I feel, predicated on the fallacy that the majority of people don’t bother organising their files, and are thus willing to accept a flat storage with complex views built at run time on top of that; while simultaneously being willing to spend a disproportionate amount of time classifying those files—without, of course, using a hierarchical structure. This is a fundamental misunderstanding of human nature.

By way of an example: if we perceive the Universe in a techno-mazdeist struggle between a πνεῦμα which creates fool-proof tools for users; and a φύσις, which creates more and more adept fools; then we can easily see that, for the entirety of history until now, the pneuma has been kicked squarely in the nuts by the physis. In other words: any design or implementation that does not take into account human nature in that particular problem space is bound to fail.

While documents might benefit from additional relations that are not simply inferred by their type or location on the file system, media files do not really have the same constraints. Especially stuff like music or videos. All the tracks of an album are in the same place not because I decided that, but because the artist or the music producers willed it that way; all the episodes of a series are in the same place because of course they are, and they are divided by season because that’s how TV series work; all the episodes of a podcast are in the same place for the same reason, maybe divided by year, or by season. If that structure already exists, then what’s the point of flattening it and then trying to recreate it every time out of thin air with a database query?

The end result of constructing a UI that is just a view on top of a database is that your UI will be indistiguishable from a database design and management tool; which is why all music management software looks very much like Microsoft Access from circa 1997 onwards. Of course you can dress it up however you like, by adding fancy views of album covers, but at the end of the day it’s just an Excel spread sheet that occasionally plays music.

Another side effect of writing a database that contains the metadata of a bunch of files is that you’ll end up changing the database instead of changing the files; you could write the changes to the files, but reconciling the files with the database is a hard problem, and it also assumes you have read-write access to those files. Now that you have locked your users into your own database, switching to a new application becomes harder, unless your users enjoy figuring out what they changed over time.

A few years ago, before backing up everything in three separate storages, I had a catastrophic failure on my primary music hard drive; after recovering most of my data, I realised that a lot of the changes I made in the early years weren’t written out to music files, but were stored in some random SQLite database somewhere. I am still recovering from that particular disaster.

I want my music player to have read-only access to my music. I don’t want anything that isn’t me writing to it. I also don’t want to re-index my whole music collection just because I fixed the metadata of one album, and I don’t want to lose all my changes when I find a better music player.

Another detour: non-local media

Yes, yes: everyone listens to streamed media these days, because media (and software) companies are speed-running Adam Smith’s The Wealth of Nations and have just arrived at the bit about rentier economy. After all, why should they want to get paid once for something, when media conglomerates can “reap where they never sowed, and demand a rent even for its natural produce”.

You know what streaming services don’t like? Custom, third party clients that they can’t control, can’t use for metrics, and can’t use to serve people ads.

You know what cloud services that offer to host music don’t like? Duplicate storage, and service files that may potentially infringe the IP of a very litigious industry. Plus, of course, third party clients that they can’t use to serve you ads, as that’s how they can operate at all, because this is the Darkest Timeline, and adtech is the modern Moloch to which we must sacrifice as many lives as we can.

You may have a music player that streams somebody’s music collection, or even yours if you can accept the remote service making a mess of it, but you’re always a bad IPO or a bad quarterly revenue report away from losing access to everything.

Writing a music player for fun and no profit

For the past few years I’ve been meaning to put some time into writing a music player, mostly for my own amusement; I also had the idea of using this project to learn the Rust programming language. In 2015 I was looking for a way to read the metadata of music files with Rust, but since I couldn’t find anything decent, I ended up writing the Rust bindings for taglib. I kept noodling at this side project for the following years, but I was mostly hitting the limits of GTK3 when it came to dealing with my music collection; every single iteration of the user interface ended up with a GtkTreeView and a replica of iTunes 1.0.

In the meantime, though, the Rust ecosystem got exponentially better, with lots of crates dedicated to parsing music file metadata; GTK4 got released with new list widgets; libadwaita is available to take care of nice UI layouts; and the Rust bindings for GTK have become one of the most well curated and maintained projects in the language bindings ecosystem.

Another few things that happened in the meantime: a pandemic, a year of unemployment, and zero conferences, all of which pushed me to streaming my free and open source software contributions on Twitch, as a way to break the isolation.

So, after spending the first couple of months of 2022 on writing the beginners tutorial for the GNOME developer documentation website, in March I began writing Amberol, a local-only music player that has no plans of becoming more than that.

Desktop mode

Amberol’s scope sits in the same grand tradition of Winamp, and while its UI started off as a Muine rip off—down to the same key shortcuts—it has evolved into something that more closely resembles the music player I have on my phone.

Mobile mode

Amberol’s explicit goal is to let me play music on my desktop the same way I typically do when I am using my phone, which is: shuffling all the songs in my music collection; or, alternatively, listening to all the songs in an album or from an artist from start to finish.

Amberol’s explicit non goals are:

  • managing your music collection
  • figuring out your music metadata
  • building playlists
  • accessing external services for stuff like cover art, song lyrics, or the artist’s Wikipedia page

The actual main feature of this application is that it has forced me to figure out how to deal with GStreamer after 15 years.

I did try to write this application in a way that reflects the latest best practices of GTK4:

  • model objects
  • custom view widgets
  • composite widgets using templates
  • property bindings/expressions to couple model/state to its view/representation
  • actions and actionable widgets

The ability to rely on libadwaita has allowed me to implement the recoloring of the main window without having to deal with breakage coming from rando style sheets:

The main thing I did not expect was how much of a good fit was Rust in all of this. The GTK bindings are top notch, and constantly improving; the type system has helped me much more than hindering me, a poor programmer whose mind has been twisted by nearly two decades of C. Good idiomatic practices for GTK are entirely within the same ballpark of idiomatic practices for Rust, especially for application development.

On the tooling side, Builder has been incredibly helpful in letting me concentrate on the project—starting from the basic template for a GNOME application in Rust, to dealing with the build system; from the Flatpak manifest, to running the application under a debugger. My work was basically ready to be submitted to Flathub from day one. I did have some challenge with the AppData validation, mostly caused by appstream-utils undocumented validation rules, but luckily it’s entirely possible to remove the validation after you deal with the basic manifest.

All in all, I am definitely happy with the results of basically two months of hacking and refactoring, mostly off an on (and with two weeks of COVID in the middle).

amberol muine music projects development rust gtk

Older posts

  1. , In which I announce the release of the first GWeather-4 developers snapshot
  2. , In which I explain what is happening in the libgweather repository
  3. , In which I explain some changes in the GObject introspection format that landed in GNOME 41
  4. , In which I explain how to build and publish your library’s API reference on GitLab
  5. , In which I outline what comes next in the developers documentation of the GNOME platform
  6. , In which I introduce a new GObject feature
  7. , In which I report about the status of gi-docgen
  8. , In which I talk about a new tool to generate the API reference for GTK
  9. , In which we talk about derivable types that are not GObject

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