[maemo-developers] Python and GStreamer

[From: Leonardo Sobral Cunha]

hi tony,

there is a bug in your code, you dont need to call createGSTPlayer in
the start method, so you will reuse the pipeline that is already
created in the constructor (__init__).

I have tested your code (without the createGSTPlayer in the start
method) with the test code below and it worked fine.

if __name__ == '__main__':
    argv     = os.sys.argv
    argc     = len(argv)

    if argc != 2:
        print 'Pass filename as parameter'
        exit

    filename = argv[1]

    sc = SoundControl()
    sc.start(filename)
    time.sleep(2)

    print "restarting"
    sc.stop()
    sc.start(filename)
    time.sleep(2)
    print "end"

BR,
-- 
// leo
-------------------------------------------------------
Leonardo Sobral Cunha
INdT - Instituto Nokia de Tecnologia
PGP: 0x5751676C @ wwwkeys.pgp.net
-------------------------------------------------------

On 8/26/07, Tony Maro <tonymaro at gmail.com> wrote:
> I've been trying to figure out how to use gstreamer to play audio.  It
> works, but sometimes it will randomly freeze my application when I try to
> start an mp3 file playing.  I'm only using two mp3 files and they both work
> at other times (like after a reboot) so I know it's not specifically the
> file.
>
> Sometimes I'll start my application which calls the start method of the
> SoundControl class below - and no sound starts.  Then, when my app tries to
> stop the music, everything freezes up.  It always seems to freeze things
> when I call "stop"
>
> After doing this, my application refuses to work at all (always freezes)
> until I reboot my n800.
>
> If anyone has any ideas, I'd greatly appreciate it.  Yes, I know there's
> probably more optimized ways to do some of what I have in this class, but
> it's grown as I've learned gstreamer, and I haven't stopped to refactor it
> yet.
>
> I've gleaned most of this code by looking at ukmp:
>
> class SoundControl(object):
>     def __init__(self):
>         print "Creating music player"
>         self.createGSTPlayer()
>
>     def createGSTPlayer(self):
>         print "Creating player"
>         self.player = gst.parse_launch( "gnomevfssrc name=source !
> dspmp3sink name=sink" ) # id3lib name=id3 !
>          self.source = self.player.get_by_name( "source" )
>         self.sink = self.player.get_by_name( "sink" )
>         self.player.set_name("player")
>         bus = self.player.get_bus ()
>         bus.add_signal_watch()
>         bus.connect('message', self.on_message)
>         print "Player created"
>
>     def start(self, filename, newVolume = 80, repeat=-1):
>         if filename == None: return
>         self.stop()
>         time.sleep(0.10)
>
>         self.createGSTPlayer()
>
>         self.filename = filename
>         self.repeat = repeat
>         self.paused = False
>         if newVolume < 0: newVolume = 0
>         if newVolume > 100: newVolume = 100
>         # self.player.set_property('uri','file://' + filename)
>         print "Setting player location"
>         self.source.set_property ("location", filename)
>         self.sink.set_property('volume',  newVolume*65535/100)
>         self.player.set_state(gst.STATE_PLAYING)
>         print "Player should be playing"
>
>     def stop(self):
>         print "stopping player"
>         self.player.set_state(gst.STATE_NULL)
>
>     def pause(self, state=None):
>         print "Pause toggle"
>         if state == None:
>             if self.paused == True:
>                 self.paused = False
>                 self.player.set_state(gst.STATE_PLAYING)
>                 return
>             self.paused = True
>             self.player.set_state (gst.STATE_PAUSED)
>             return
>         if state == True:
>             self.player.set_state(gst.STATE_PAUSED)
>         else:
>             self.player.set_state(gst.STATE_PLAYING)
>
>     def on_message(self, bus, message):
>         t = message.type
>         if t == gst.MESSAGE_EOS:
>             if self.repeat == -1:
>                 print "Repeat enabled"
>                 time_format = gst.Format(gst.FORMAT_TIME)
>                 self.player.seek_simple(time_format, gst.SEEK_FLAG_FLUSH, 0)
>                 self.player.set_state(gst.STATE_PLAYING)
>                 return
>             if self.repeat > 0:
>                 print "Repeat enabled"
>                 self.repeat = self.repeat - 1
>                 time_format = gst.Format(gst.FORMAT_TIME)
>                 self.player.seek_simple(time_format, gst.SEEK_FLAG_FLUSH, 0)
>                 self.player.set_state (gst.STATE_PLAYING)
>                 return
>             print "No repeat, stopping"
>             self.player.set_state(gst.STATE_NULL)
>         elif t == gst.MESSAGE_ERROR:
>             print "Streamer error"
>             self.player.set_state(gst.STATE_NULL)
>
>
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>
>


-- 
// leo