Archive for the ‘exaile’ Category

BPM autodetection using python + GStreamer’s bpmdetect plugin

Sunday, August 16th, 2015

I recently found the bpmdetect element in GStreamer, and thought it would be neat to try it out and see how well it works. The GStreamer bpmdetect plugin is mostly undocumented, so I had to dig in the source code to figure out how to extract tags from it. The operation is pretty simple:

  • Setup a pipeline to read in a file, put a fakesink at the end of the pipeline and set ‘sync’ to false
  • Insert the bpmdetect element
    • However, due to this bug, insert a capsfilter before the element to mix it down to a single channel!
  • Attach a message handler, and listen for taglist messages
    • If you already have the BPM tag on the file, then it will be emitted by whatever is decoding the audio too. So, what I do is look for messages that *only* have the beats-per-minute tag in the tag list
    • The bpm is accumulated, so the last BPM message you get will be the calculated rate

Pretty simple! Of course, the results are only as reliable as libsoundtouch’s BPM detection is… but it seems to be correct at least some of the time. Expect to see this code in Exaile soon as a companion to the manual BPM counter! 🙂

Code is available in a gist on github:

GTK3 Composite Widget Templates for Python

Sunday, May 24th, 2015

Recently, the other developers of the Exaile audio player and I decided to finally migrate to GTK3 and GStreamer 1.x. I mentioned that I wanted to use some code I had developed a few years ago to get rid of the manual UI building code that we had and replace it with GtkBuilder XML files, and @mathbr noted that GTK had added a new feature called ‘composite widget templates’ a few years ago. The ideas were similar to mine, and reading the comments in a blog post about the Vala implementation inspired me to create a working version of this for Python. The first implementation took a few hours, and I’ve been adding improvements ever since as I’ve been integrating this into Exaile.

Here’s how the vala demo code from that blog post looks like in Python, turns out it’s not *that* different:

from __future__ import print_function
from gi.repository import Gtk
from gi_composites import GtkTemplate

class MyWidget(Gtk.Box):

    __gtype_name__ = 'MyWidget'
    entry = GtkTemplate.Child()

    def __init__(self, text):
        super(Gtk.Box, self).__init__()
    def button_clicked(self, widget):
        print("The button was clicked with entry text: %s" % self.entry.get_text())

    def entry_changed(self, widget):
        print("The entry text changed: %s" % self.entry.get_text())

The key pieces to note are:

  • Use the @GtkTemplate decorator to load the template for your widget
  • Use GtkTemplate.Child to create attributes on your widget that will be loaded from the XML file (there’s also GtkTemplate.Child.widgets(n) if you need to declare multiple widgets)
  • Use @GtkTemplate.Callback decorator to mark methods to be connected to signals as declared in the XML file

For the full demo + associated GtkBuilder XML file check out the github repo.

I’d love to see this functionality included with GTK’s python bindings, and in fact after creating this I found a bug open on the GNOME bugzilla with a patch to PyGObject to allow python users to use it, but for whatever reason it never got merged. My implementation works on the current release of PyGObject, and possibly older versions too.

Want to get rid of boilerplate in your GTK3 python application? Check out the examples/code on github.

Use GroupTagger to rapidly organize your audio files with Exaile 3.3.0 using the Grouping tag

Saturday, October 6th, 2012

Well, I haven’t blogged here in quite awhile, but it’s been a pretty busy year! One project I’ve been spending a fair amount of time on is Exaile, a cross platform music player for GTK+ (its free and works on Windows, Linux, and even OSX — though, the installation for OSX is rather tricky). I’ve been DJ’ing Lindy Hop dances for almost a year now, and I’ve been fixing up Exaile to be an awesome music player for DJing — adding a BPM counter, secondary output device support (sometimes called pre-listening), and other things that I’ve found to be useful.

One feature in particular I want to highlight is a plugin I’ve created called GroupTagger. This super-useful plugin is distributed with the latest stable version of Exaile. This plugin allows you to easily and rapidly organize your music using the ‘Grouping’ tag in your audio files. The best part about this is that the data is stored in your MP3/OGG/FLAC/whatever audio files, so you can use the data with your favorite audio player if it supports it (Winamp, iTunes, others already do). A lot of people already categorize their music using this tag, and this plugin can manage music that is already tagged this way. To illustrate how useful this is, here are some screenshots and a mini-tutorial.


BPM Counter Plugin for Exaile 0.3.2

Monday, October 3rd, 2011

I’ve been starting to use my desktop machine at home a lot lately, so I’ve been looking for a cross-platform audio player that I can use that doesn’t annoy me. After a long search (and discarding most of the linux audio players: amarok, banshee, etc as too annoying or not the right features or whatever) I finally stumbled across Exaile, which not only doesn’t annoy me greatly, but it’s written in python so its way easy to modify and figure out what it does 🙂

I’ve been doing a bit of swing dancing lately (in particular Lindy Hop), so I’ve been gathering music together to listen to, and I need BPM for the music… one thing Exaile did not already have was a BPM counter, so I wrote a manual beat counter for it. You can write plugins for Exaile, though the documentation is rather sparse. I must say though, using the GLADE widget editor thing has to be the most annoying GUI design tool ever…

Download it at my usual software site.

PS: In case anyone asks, I’m not interested in writing an automated beat counter… this works well enough for me 🙂