Crate legacylisten

source ·
Expand description


legacylisten is a simple CLI audio player I wrote because no existing one fulfilled my needs. The main feature is that you can change how often a song is played (legacylisten is always on shuffle-all), but there are some other even odder features.

How it works

legacylisten creates a list of all songs in ~/.zvavybir/legacylisten/data1 and sub directories together with their associated so-called “playing likelihood”2 and volume (the standard values are 10 and 10% respectively). Then it will choose a song at random with the probability proportional to it’s playing likelihood and plays it, unless you request something different.

The volume is adjustable on a per-song basis and is saved. Although simple (ridiculously trivial indeed) to implement, there is no way to change the global volume, since I figured that this is better left to the operating system. What a audio player can do very good is recognizing which song is playing and acting according to it. The intended use of that feature is to adjust the volume of very quiet songs once and than the user doesn’t have to be bothered ever again.

Another quite obscure feature is that you can not only pause/quit immediately, but also only on the end of the current song, but the strangest one is that legacylisten will sever all connection to the disk if the *NIX signal SIGUSR1 arrives and only starts reading again when SIGUSR2 arrives. SIGUSR1 doesn’t interrupt an already playing song since songs are buffered3.


Commands are how legacylisten is controlled and consist always out of a single character. Originally these were the first letter of the command name, but since this caused rather strange names (like f – “fainter” – to decrease the volume), I settled to just number them through alphabetically.

To execute a command, just type it’s letter (but remember that terminals are usually line-buffered, meaning that until you press enter legacylisten won’t see – and react to – your input).

The following commands exist:

  • ?: Shows a list of all command with a help message (essentially this very one).4
  • a: Increases playing likelihood of the current song by 1.
  • b: Decreases playing likelihood of the current song by 1.
  • c: Quits legacylisten and saves the songs likelihoods and volumes to ~/.zvavybir/legacylisten/songs.csv.
  • d: Pauses playing.
  • e: Resumes playing after pausing with d or l (doesn’t overwrite SIGUSR1 though).
  • f: Skips song.
  • g: Increases permanently the volume of the current song by 1% (but not above 100%).
  • h: Decreases permanently the volume of the current song by 1% (but not below 0%).
  • i: Shows how long the song is already playing and – if available5 – how long it will take in total.
  • j: Switches between playing and pausing.
  • k: Quits legacylisten as soon as the current song has finished playing (takes precedence over l).
  • l: Like k, but just pauses instead of quitting.
  • m: Shows the metadata in the song’s id3 tag (the length usually has to be queried by i since it’s rarely saved in the id3 tag).
  • n: Opens the cover image of the song in your preferred image viewer (it uses mimeopen which is AFAIK not available on MS Windows, so this won’t work there). If the song has no cover it opens ~/.zvavybir/legacylisten/default.png (doesn’t need to be an PNG file) instead. For the fallback image I use (and made, so it’s quite bad) see here.
  • o: Stops all repeating (but if the current songs is an repetition it’s not ended immediately; if you want that also skip with f).
  • p: Repeats the current song once.
  • q: Repeats the current song forever.
  • r: Skips to the beginning of the current song or – if it already is at the beginning – to the previous one. You can go as many songs back as you want (or more precisely how many there are). All played songs are saved (but only in one run of legacylisten, if you restart it the history is lost) and if you went back the next song is the same as previously followed on that song.

Low memory handler

As already briefly pointed out previously, especially older versions of legacylisten had an horrendous memory footprint, which rendered my system unusable for a few seconds a couple times. Under Linux such problems are usually handled by the OOM killer (which ends the process with least importance and largest memory consumption), but it turns out that the Chromium web browser (the free software variant of Google Chrome), which out of other reasons I’m forced to use every once in a while, is even worse than my crimes. Instead of doing something sensible, I added a routine to legacylisten that watches the amount of free memory and terminates itself when it falls under some certain (configurable) threshold (a GiB currently).

This uses currently a wrong notion of “free ram” (it counts memory used for disk caching as used although it’s not; see this famous site for more), so it triggers unnecessarily. Although this is better than the reverse, the low memory handler is off as default because of that.

This uses the *NIX function sysconf(3), so it won’t work on outdated platforms.

Configuration file legacylisten can be configured by the

~/.zvavybir/legacylisten/conffile.csv file. If an option can’t be parsed it’s just silently ignored, so be careful. Every option has an own line (with mandatory newline at the end, even for the last line and under MS Windows) and every part of it has to be comma-separated. As an example, this is my configuration file:


There are currently six possible options:

  • data_dir: If you have your music collection somewhere else (like me on an external hard drive or in ~/Music) you can use this option to change the directory legacylisten will search. The ~/ notation is not usable in the configuration file, even under *NIX systems.
  • minimum_ram: The threshold for the low memory handler in bytes.
  • ignore_ram: Disables the low memory handler (possible values are true and false). If this is set (currently the default) minimum_ram is ignored.
  • lang: legacylisten supports basic internationalization and this is the option to activate it. There are currently five possible values for this option:
    • english: Sets the language to English (this is the default).
    • german or deutsch: Sets the language to German.
    • esperanto: Sets the language to Esperanto.
    • dutch or nederlands: Sets the language to Dutch.
    • custom: If you have a translation file, but it’s not included in the official sources (maybe because you’re still working on finishing it, you just want to try something out or you are forbidden by legal reasons to publish it under legacylisten’s license) this option enables you to still use it. This option requires two further values, the path to the translation file and the language ID. As an example, if English weren’t included already you could use such an option to circumvent that:
      The path has no requirements about filename or file extension, but the language identifier has to be correct.

Plugin interface

In case there is no metadata tag in the song, you can use the plugin interface to tell legacylisten the song’s title and artist. Every plugin is a shell script (or executable if you prefer) in the ~/.zvavybir/legacylisten/parser directory (or sub directories thereof) and gets the song’s file name (without new line character) as input (on stdin). If the file name could be parsed it has to output the song’s title and artist (delimited by zero bytes and optionally a trailing zero byte) on stdout. If no zero bytes are in the output the parsing is treated as having failed and will be ignored.


The simplest way to install legacylisten is with rustup and Cargo. After installing rustup as indicated on it’s website, issue to following command to install legacylisten itself:

cargo install legacylisten


As every software legacylisten too always can be improved. While I’m trying to get it usable alone, I don’t have unlimited time and especially not always the best ideas. If you can help with that or on some other way (like with a feature request, an additional language or documentation improvements) please help.

I assume that unless stated otherwise every contribution follows the necessary license.


Though unusual for a rust program, legacylisten is released under the GNU General Public License version 3 or (at your option) any later version.

For more see

  1. Although not intended (even to the contrary) legacylisten should be quite portable (~/ refers to the user’s home directory – in legacylisten even under MS Windows). 

  2. Or “likelihood” for short. 

  3. This is of course quite bad on the memory footprint, but it’s the best I could manage so far (at least it’s a whole magnitude better than the worst implementation I had). If you have an better idea, please contribute

  4. This command is a bit special since it’s handled differently internally. You can see this on the one hand directly by it’s special name (only non-letter one) and on the other hand (when you run legacylisten) that while usually commands are executed strictly in order this one is run before all others specified on the same line. 

  5. legacylisten tries to read it out of the metadata of the audio file or – if that fails (which happen often, since the underlying routine seems to be still work-in-progress) – decodes the whole song a second time to get the length on a simple, but costly way after a short waiting period. Until that is fixed (if you can help, please contribute) I wouldn’t recommend skipping multiple songs in short sequence, since per song there’s one thread trying to decode it – even after it’s already certain that it’s never needed. 


  • Module for API of legacylisten
  • Module for handling audio.
  • Module for handling commands.
  • Enables custom configuration if used as a library.
  • Handles internationalization and some localisation of legacylisten.
  • Entry point for legacylisten.
  • Handles song choosing and processing


  • legacylisten’s Error type.