After several months thinking about it, and just two requests, I finally decided
satyr's code. I decided to use github because I already switched to
git, mainly for testing and understanding it. I think I
can live with
hg, althought branch management in
git seems to be given more
thought and a good implementation.
So, without further ado: satyr in github
Remember, it's still a test software, by no means polished or ready for human
consumption, and with very low development force. Still, I think it has some
nice features, like interchangeable skins and a well defined backend,
support, quick tag edition, reasonable collection managment, and, thanks to
Phonon, almost-gapless playback and things like «stop after playing the
current this file» (but not «after any given file» yet).
In Debian Sid it mostly works only with the
GStreamer backend; I haven't tried
xine one and I know
VLC does not emit a signal needed for queueing the
next song, so you have to press «next» after each song. AFAIK this is fixed
satyr-0.3.2 "I should install my own food" is out. The Changelog is not very impressive:
- We can save the list of queued Songs on exit and load it at startup.
- The queue position is not presented when editing the title of a Song that is queued.
- Setting the track number works now (was a bug).
- Fixed a bug in setup.py.
but the last one is somewhat important (Thanks Chipaca). Also, 2 months ago, I made the satyr-0.3.1 "freudian slip" release, when user 'dglent' from http://kde-apps.org/ found a packaging bug. It was not only a bugfixing revision, it also included new features:
- nowPlaying(), exported via dbus.
- 'now playing' plugin for irssi.
- Changes in tags is copied to selected cells (in the same column). This allows 'Massive tag writing'.
- Fixed "NoneType has no attribute 'row'" bug, but this is just a workaround.
- Forgot to install complex.ui.
Now go get it!
One of the things I had to while developing
satyr is building a model for a
QListViewer. It should be straighforward from qt's documentation, but I found
a couple of things that I would like to put in a post, specially because there
doesn't seem to be much models in
PyQt4 easily found in the web.
According to its description, a subclass of
QAbstractListModel as this one
should mostly implement the
rowCount() methods, which is true.
This example creates a read-only model, so no need to implement
but given the simplicity of
data(), it doesn't seem too difficult to do. I
also wanted it to react when more
Songs were added on the fly.
data() is the most important one. It is not only used for
retrieving the data itself, but also some metadata useful for showing the data,
like icons and other stuff. For selecting what the caller wants, it refers a
Qt.ItemDataRole. The role for the data itself is
Qt.DisplayRole. One of the
particularities of this method is that it could be called with any vegetable as
input; namely, it can refer to a row that does not exist anymore or for metadata
that you don't care about. In those cases you must return an empty
None. So, a first implementation is:
def data (self, modelIndex, role): if modelIndex.isValid () and modelIndex.row ()<self.count and role==Qt.DisplayRole: # songForIndex() returns the Song corresponding to the row song= self.songForIndex (modelIndex.row ()) # formatSong() returns a QString with the data to show data= QVariant (self.formatSong (song)) else: data= QVariant () return data
This method, together with a
rowCount() that simply returns
enough for showing data that is already there. Notice that the
be not valid, and in this case we only care about its row because we're a list.
But then I wanted my
QListViewer to show songs progresively as they are
loaded/scanned and also as they are found as new. But then a problem arises:
the view is like a table of only one column. The width of this colunm at the
begining is the same width as the
QListView itself. But what happens when the
string shown is too big? What happens is that it gets chopped. We must inform
the view that some of the rows are bigger. That's where the metadata comes into
Another possible role is
Qt.SizeHintRole. If we return a size instead of an
QVariant, that size will be used to expand the column as needed, even
giving us a scrollbar if it's wider that the view.
Now, we're supposed to show the tags for the
Song (that's what
does if possible; if not, it simply returns the filepath), so this width should
be calculated based on the length of the string that represents the song. But
if we try to read the tags for all the songs as we load the
Collection, we end
up with too much disk activity before you can show anything to the user, which
is unacceptable. So instead we calculate based on the filepath, which is used
Songs with too few tags anyways. Here's the hacky code:
... # FIXME: kinda hacky self.fontMetrics= QFontMetrics (KGlobalSettings.generalFont ()) ... def data (self, modelIndex, role): if modelIndex.isValid () and modelIndex.row ()<self.count: song= self.songForIndex (modelIndex.row ()) if role==Qt.DisplayRole: data= QVariant (self.formatSong (song)) elif role==Qt.SizeHintRole: # calculate something based on the filepath data= QVariant (self.fontMetrics.size (Qt.TextSingleLine, song.filepath)) else: data= QVariant () else: data= QVariant () return data
The last point then is reacting to
Songs are added on the fly. This is also
easy: you tell the views you're about to insert rows, you insert them, tell the
views you finished, and then emit
def addSong (self): # lastIndex keeps track of the last index used. row= self.lastIndex self.lastIndex+= 1 self.beginInsertRows (QModelIndex (), row, row) # actually the Song has already been added to the Collection # so I don't do anything here, # but if you keep your rows in this model you should do something here self.endInsertRows () self.count+= 1 modelIndex= self.index (row, 0) self.dataChanged.emit (modelIndex, modelIndex)
Later I'll post any peculiarities I find porting all this stuff to a read/write
 That's material for another post :)
 This feature can be said to be a little too much. Actually, I get a flicker when scanning.
 Of course the next step is to use a table view and make a model for it.
 Right now the load time for a
Collection of ~6.5k songs is quite long as
 This is a design decision which is not relevant to this example.
So far both the default and complex skins in
satyr were (ab)using the selection
in their respectives views to highlight the current song and, in the case of the
complex skin, that meant that you couldn't select cells. This could be (and will
be) handy for editing several tags at the same time or for grouping songs in an
Album. I decided that this should not longer be this way.
It was really simple: I simple reenabled selection, the extended version (Shift
and Control work as you grew to spect). Now the way to highlight the current
song is to simply change the background and foreground colors for the cells of
that row. How? Simple, extending the
QPlayListModel.data() method to provide
these properties and using
QApplication.palette() to get colors that would
stand out from the normal application colors (even the selection) and would
still make the text readable:
def data (self, modelIndex, role): if modelIndex.isValid () and modelIndex.row ()<self.aggr.count: [...] # check the row so we highlight the whole row and not just the cell elif role==Qt.BackgroundRole and modelIndex.row ()==self.parent_.modelIndex.row (): # highlight the current song # must return a QBrush data= QVariant (QApplication.palette ().dark ()) elif role==Qt.ForegroundRole and modelIndex.row ()==self.parent_.modelIndex.row (): # highlight the current song # must return a QBrush data= QVariant (QApplication.palette ().brightText ()) [...]
And that's almost it... because there's always a but. Whenever the current song
changes, there's a little lag between this happens (you can hear the new song
being played) and the highlighting updates. This is because I update that
self.parent_.modelIndex you see up there, but the
QPLM.data() method is not
called until the next repaint, which doesn't happen inmediately. So, we must
force that repaint. How? Again, it's simple: we already emited the
dataChanged() signal in the method
setData() when the data could be
successfully changed. Now we do the same just so the view updates the
def showSong (self, index): [...] # FIXME? yes, this could be moved to the model (too many self.appModel's) start= self.appModel.index (oldModelIndex.row (), 0) end= self.appModel.index (oldModelIndex.row (), columns) self.appModel.dataChanged.emit (start, end) start= self.appModel.index (self.modelIndex.row (), 0) end= self.appModel.index (self.modelIndex.row (), columns) self.appModel.dataChanged.emit (start, end) [...]
I figured several things after the last/first release. One of those is that one can't try to pull a beta of your first releases. Betas are for well stablished pieces of code which are supposed to be rock solid; initial releases not. Another thing I figured out (or actually remembered) is that old saying: release early, release often.
So instead of a
0.1 'official' release, where all the bugs are nailed down in
their coffins and everything is as peachy and rock solid as a peachy huge rock
(like the Mount Fitz Roy,
for instance), and only 13 days later than the initial release, we get another
satyr-0.2, codenamed "I love when two branches come
together", is out.
This time we got that pharaonic refactoring I mentioned in the last release, which means that skins are very independient from the rest of the app, which is good for skins developers and the core developers, even if those sets are equal and only contain me.
From the user point of view, the complex skin is nicer to see (column widths and headers, OMG!) and it also allows tag editing. Yes, because we have tag editing! Right now the only way to fire the edition is to start typing, which will erase previous data, but don't worry, I plan to nail that soon. At least it's usefull for filling up new tags. I also fixed the bug which prevented this skin to highlight which is being played. Lastly but not leastly, the complex skin has a seek bar, and the code got tons of cleanups.
So, that's it. It's out, go grab it!
 Right now I would consider
satyr just a small peeble in a highway, only
noticeable if some huge truck picks it up with its wheels and throws it to your
windshield. But I plan to reach at least to be a sizable rock such as that one
found near one of the Vikings in Mars.
More than two months ago I globed about QStrings and
The problem was this: my app accepts paths via command line, which are
KCmdLineOptions; which in turn converts everything to
QStrings. What I wanted were paths, which are more like
QStrings (because the latter have internally an unicode representation;
more on that later). Including
PyQt4 in the equation forced me to resort
QByteArray to get the path as a
str instead of using
PyQt4 doesn't export that function). But that's
only the beginning of the problem.
Take for instance this situation. I have a music collection that I've been
building for years now (more that 10, I think). In the old times of this
collection the filenames were encoded in
iso-8859-1. Then the future came
and converted all my machines to
utf-8. But only the software; the
filesystems were in one way or another inherited from system to system, from
machine to machine. So I ended with a mixture of utf and iso filenames, to
the point where I have a file whose filename is in iso, but the directory
where it is is in utf. Yes, I know, it is a mess. But if I take any decent
media player, I can play the file allright. That's because the filesystem
knows nothing of encodings (otherwise it would reject badly encoded
I just spent last saturday making sure that
satyr only stored filepaths in
QStrings. It took concentration, but having just
a bunch of classes and only 3 or 4 points where the filepaths are managed it
wasn't that difficult. Still, it took a day. But then, as I mentioned in
Phonon the is not able to play such files... or so I thought.
If you run
satyr after executing
export PHONON_XINE_DEBUG=1 you'll see a
Phonon debug info in the console (not that there is another way to
satyr right now anyways). Among all that info you'll see lines such as
void Phonon::Xine::XineStream::setMrl(const QByteArray&, Phonon::Xine::XineStream::StateForNewMrl) ... bool Phonon::Xine::XineStream::xineOpen(Phonon::State) xine_open succeeded for m_mrl = ...
If you're sharp enough (I'm not; sandsmark from
#phonon had to tell me)
you'll note the mention of MRL's. MRL's are
xine's URL for media. As any
URL, they can (and most of the time must) encode 'strange' characters with
the so-called "percent encoding". This means that no matter what encodings
the different parts of a filepath is in, I just add
file:// at the
beginning and then I can safely encode it scaping non-ascii characters to
%xx representations... or that's what the theory says. One thing to note is
file:// part must not be scaped;
xine complains that the file
does not exist in that case.
Looking for help in
Qt's classes one can find
QUrl and the already known
QByteArray. I can call
QByteArray.toPercentEnconding() from my
feed that to
QUrl.fromPercentEncoding() (which strangely returns a
QString, which is exactly what we're avoiding) or
But then the first function encodes too much, replacing
%3A%2F%2F. No fun.
Ok, let's try creating a
QByteArray with only the
file:// and then
toPercentEncoding() of the path only. It works:
But then calling
<span class="createlink">PyQt4</span>.QtCore.QUrl("file://xn--/home/mdione.../ltimo bondi a finisterre/07- la pequea novia del carioca-wkmz60758d.wav")
The URL got somehow puny-encoded,
which of course
xine doesn't recognize for local files.
Another option is to create an empty
QUrl.StrictMode so we avoid 50 lines of code that start
that try to escape everything all over again (and I already had some
double-or-even-triple-enconding nightmares parsing RSS/Atom feeds last year,
thank you), but we get puny-encoded again (maybe it is 'pwny-encoded'?).
Last resort: backtrack to the point were we created only one
with the path and call
toPercentEncoding(); feed that to the method
setEncodedPath() of an empty
QUrl. Then we add the last piece calling
setScheme('file') and we're ready! Of course we're not:
Notice the lack of the two
xine doesn't like it;
hence, I don't either.
Ok, this post got too long. I hope I can resolve this soon, I already spent too much time on it. At least a good part of it was expaining it, so others don't have to suffer the same as I did.
satyr will shortly be released, whether I fix this bug or not.
 Look at the size of that file! 6k lines to handle URL's! Who would say it was so difficult... Once more I'm remembered of how lucky I am to have this libraries at the tips of my fingers, yay!
Since a long ago I'm looking for a media player for listening my music. In that aspect I'm really exigent. Is not that I need lots of plugins and eye candy, no, I just need a media player that fits my way to listen music.
How do I listen to music? All day long, for starters. I have a collection of
.ogg files, which I normally listen in random mode. From time to time I
want to listen certain song, so I either queue it or simply stop the current
one and start the one I want. Sometimes I enqueue several songs, which might
not be related between them (maybe only in my head they are).
I've been using
Amarok, I really like its random albums feature; that is,
I listen to a whole album, and when it finishes, another album is picked at
random and I listen to all its songs. The last feature, a really important
one: My collection is my playlist and viceversa. I don't build playlists; if
I want to listen to certain songs I just queue them. One feature I like also
is a tag editor and the posibility to rearrange the songs based on its tags
(with support for albums with songs from various authors, like OST's). Last
but no least, reacting to new files in the collection is also well regarded.
I used to use
xmms. I still think it's a very good player for me, but it
lacks utf support and doesn't react when I add songs to the collection. Then
Audacious (I was using it up to
today) and probably a couple more. None of them support all the features, so
today, completely tired of this situation, I started writing my own. I
Satyr. Another reason to do it is to play a little more with
PyKDE. Talking about
KDE, I know the existence of
minirok, but it uses
GStreamer, and I wanted to play with
So, what's different in this media player? If you think about it, if you have a CD (vinyl, cassettes maybe?) collection in your home, what you have is exactly that: a collection of Albums. Most media players manage Songs, grouping them in Albums and by Author too. Notably Amarok used to manage Albums with several artists (what's called a 'Various artists' Album), but since Amarok 2 it doesn't do it anymore, nor the queuing works. So the basic idea is exactly that: you have a Collection of Albums, most of them with songs from the same Author (and sometimes Featuring some other Authors), but sometimes with Songs from different Authors. Of course I will try to implement all the features I mentioned above.
Ok, enough introduction. This post was aimed to show some code, and that's what I'm going to do now. This afternoon I was testing the Phonon Python bindings, trying to make a script to play a simple file. This snippet works:
# qt/kde related from <span class="createlink">PyKDE4</span>.kdecore import KCmdLineArgs, KAboutData, i18n, ki18n from <span class="createlink">PyKDE4</span>.kdeui import KApplication # from <span class="createlink">PyKDE4</span>.phonon import Phonon from <span class="createlink">PyQt4</span>.phonon import Phonon from <span class="createlink">PyQt4</span>.QtCore import SIGNAL media= Phonon.MediaObject () ao= Phonon.AudioOutput (Phonon.MusicCategory, app) print ao.outputDevice ().name () Phonon.createPath (media, ao) media.setCurrentSource (Phonon.MediaSource ("/home/mdione/test.ogg") media.play () app.connect (media, SIGNAL("finished ()"), app.quit) app.exec_ ()
Of course, this must be preceded by the bureaucratic creation of a
KApplication, but it basically plays an ogg file and quits. You just have
to define a
MediaObject as the source, an
AudioOutput as the sink, and
createPath between them. As you can see, with Phonon you don't
even have to worry about where the output will be going: that is defined by
the system/user configuration. You only have to declare that your
AudioOutput is going to play Music (the second actual line of code).
There are a couple of peculiarities with the
Python bindings. First of
Phonon comes both with Qt and separately. The separate one has a
binding in the
PyKDE4 package, but it seems that it doesn't work very
well, so I used the
PyQt binding. For that, I had to install the
python-pyqt4-phonon package. Second, the bindings don't support to call
setCurrentSource() with a string; you have to wrap it in a
The original API supports it. Third, it seems that
is not supported by the bindings either, so I had to build the
by hand. I don't care, it's just a couple lines more.
This code also shows the name of the selected
OutputDevice. I my machine
HDA Intel (STAC92xx Analog).
In the following days I'll be posting more info about what comes out of this project. I will only reveal that right now the code has classes called Player,and Collection. It can scan a Collection from a path given in the command line and play all the files found there. Soon more features will come.
 I'm not planing to do anything about it... yet.
satyr got the possibility to queue songs for playing very early. At that
moment there wasn't any GUI, so the only way to (de)queue songs was via
dbus. Once the GUI was there, we had to provide a way to queue songs. As
satyr aims to be fully usable only using the keyboard, the obvious way was to
setup some shortcut for the action.
Qt and then
KDE have a very nice API for defining 'actions' that can be
fired by the user. The ways to fire them include a shortcut, a menu entry or a
button in a toolbar. I decided to go with the
According to the
documentation, to create an action is just a matter of creating
the action and to add it to an
actionCollection(). The problem is that nowhere
it says where this collection comes from. There's the
but creating one and adding the actions to it seems to be not enough.
If you instead follow the
see that it refers to a
KXmlGuiWindow, which I revised when I was desperately
looking for the misterious
actionCollection(). I don't know why, but the
documentation generated by
PyKDE does not include that method. All in all, the
tutorial code works, so I just ported my
class MainWindow (KXmlGuiWindow): def __init__ (self, parent=None): KXmlGuiWindow.__init__ (self, parent) uipath= __file__[:__file__.rfind ('.')]+'.ui' UIMainWindow, _= uic.loadUiType (uipath) self.ui= UIMainWindow () self.ui.setupUi (self) [...] self.ac= KActionCollection (self) actions.create (self, self.actionCollection ())
def create (parent, ac): '''here be common actions for satyr skins''' queueAction= KAction (parent) queueAction.setShortcut (Qt.CTRL + Qt.Key_Q) ac.addAction ("queue", queueAction) # FIXME? if we don't do this then the skin will be able to choose whether it # wants the action or not. with this it will still be able to do it, but via # implementing empty slots queueAction.triggered.connect (parent.queue)
Very simple, really. But then the action doesn't work! I tried different approaches, but none worked.
The tutorial I mentioned talks about some capabilities of the
one of them, the ability to have the inclusion of actions in menues and
toolbars dumped and loaded from XML file (hence, the XML part of the class
name), and that is handled by the
setupGUI() method. From its documentation:
«Configures the current windows and its actions in the typical
[...] Typically this function replaces
createGUI()». In my case the GUI is
already built by that
self.ui.setupUi() that you see up there, so I ignored
this method. But the thing is that if you don't call this method, the actions
will not be properly hooked, so they don't work; hence, my problem. But just
calling it make the actions work! I'll check later what's the magic behind this
method. For now just adding
self.setupGUI() at the end of the
So, that's it with actions. As a result I also get several things: a populated menu bar with Settings and Help options (but no File; that'll come later with standard actions, of which I'll talk about later, I think), with free report bug, about satyr and configure shortcuts options, among others. The later does work but its state is not saved. That also will come in the same post that standard actions.
PD: First post from my new internet connection. Will
satyr suffer from this?
Only time will tell...
 then you had to pick the index of the songs either by guessing or looking at the dump of the playlist.
In my last
I said «The next step is to make my
Player class to export its methods
DBus and that's it!». Well, tell you what: is not that easy. If you
try to inherit from
dbus.service.Object you get this error:
In : class Klass (QtCore.QObject, dbus.service.Object): pass <span class="createlink">TypeError</span>: Error when calling the metaclass bases metaclass conflict: the metaclass of a derived class must be a (non-strict) subclass of the metaclasses of all its bases
This occurs when both ancestors have their own metaclasses. Unluckily
Python doesn't resolve it for you. The answer is to create a intermediate
metaclass which inherits from both metaclasses (which we can obtain with
type()) and make it the metaclass of our class. In code:
class <span class="createlink">MetaPlayer</span> (type (QObject), type (dbus.service.Object)): """Dummy metaclass that allows us to inherit from both QObject and d.s.Object""" pass class Player (QObject, dbus.service.Object): __metaclass__= <span class="createlink">MetaPlayer</span> [...]
Is that it now? Can I go and do my code? Unfortunately no. See this:
qdbus org.kde.satyr / /player Cannot introspect object /player at org.kde.satyr: org.freedesktop.DBus.Python.KeyError (Traceback (most recent call last): File "/usr/lib/pymodules/python2.5/dbus/service.py", line 702, in _message_cb retval = candidate_method(self, *args, **keywords) File "/usr/lib/pymodules/python2.5/dbus/service.py", line 759, in Introspect interfaces = self._dbus_class_table[self.__class__.__module__ + '.' + self.__class__.__name__] <span class="createlink">KeyError</span>: '__main__.Player' )
This is the class
dbus.service.Object complaining something else. It's
getting late here and I'm tired, so I'll continue tomorrow.
Satyr handles paths. There are some problems with paths and (sigh)
encondings. Of those, here are two: there's no way to know in which encoding
the filenames in a filesystem are enconded (f.i., there's no way to ask the
filesystem), and even if that were possible, the filenames might not even be
enconded in that enconding. In these (still!) transitioning times, lots and
lots and shitloads of filesystems are used in UTF-8 environments, but some
filenames are still in old ISO-8859-1 or whatever the system was using
QString. I'm taking a path from the command line; this path is
the location of the (right now only)
Collection for the player. I'm
handling the command line using
KCmdLineOptions, which returns
As we all know,
QString, just like the
unicode type in
all the data internally as Unicode, which is The Right Thing™. If you
really need the internal data, say as bytes, you can always call the
constData() method and be happy with it. This would be the case for paths;
you need the bytes.
PyQt4. For some reason, which maybe I will ask in the pyqt
constData() is not available. What to do? Well, that's what this post is
about. What you're about to read is hacky as it can be, but then it works. I
might feel dirty, but I can live with it. As long as I mark it as a
utter/über hack and promise to revert it once that's possible...
# path is a QString qba= QByteArray () qba.append (path) path= str (qba) # now path is a list of bytes/string.
Even if this part of the bug is fixed, then
Phonon.MediaObject.play() fails when feeded that same path with this
ERROR: backend <span class="createlink">MediaObject</span> reached <span class="createlink">ErrorState</span> after 1 . It seems a <span class="createlink">KioMediaStream</span> will not help here, trying anyway.
or simply refusing to continue. Sure, in my case I should simply ignore the filename and inform the user what's going on, but sometimes you can't be so gentle.
 but then it doesn't make much sense now since Phil wants to get rid of QString (for several reasons, which might most possibly include this one).