using gstreamer, playing a playlist without stopping the sink

Question

I want to add playlist functionality to my music player. The first track in the list plays. And typing "next" in the console and hitting return should start playing the next track but song stops playing and nothing happens.

setting the state to GST_STATE_READY instead of GST_STATE_NULL before changing the "location" also does not work.

Can someone correct my code and tell me where I am wrong?

import pygst, gobject, time, sys
pygst.require("0.10")
import gst

class AudioPlayer:
         def __init__(self):
                 self.songs = ['Holy Diver.mp3','Paranoid.mp3','Fast as a Shark.mp3']

                 # create a new gstreamer pipeline
                 self.pipeline = gst.Pipeline("mypipeline")

                 # add a file source to the pipeline
                 self.filesrc = gst.element_factory_make("filesrc","source")
                 self.pipeline.add(self.filesrc)

                 # add a generic decoder to the pipeline and link it to thesource
                 self.decode = gst.element_factory_make("decodebin","decode")
                 self.decode.connect("new-decoded-pad", self.decode_link)
                 self.pipeline.add(self.decode)
                 self.filesrc.link(self.decode)

                 # add a convertor to the pipeline
                 self.convert = gst.element_factory_make("audioconvert","convert")
                 self.pipeline.add(self.convert)

                 # add an alsa sink to the pipeline and link it to theconvertor
                 self.sink = gst.element_factory_make("alsasink", "sink")
                 self.pipeline.add(self.sink)
                 self.convert.link(self.sink)

                 # start playing
                 self.filesrc.set_property("location", self.songs.pop(0))
                 self.pipeline.set_state(gst.STATE_PLAYING)

         def decode_link(self, dbin, pad, islast):
                 pad.link(self.convert.get_pad("sink"))

         def next(self):
                 self.convert.unlink(self.sink)
                 self.filesrc.set_state(gst.STATE_NULL)
                 self.filesrc.set_property("location", self.songs.pop(0))
                 self.convert.link(self.sink)
                 self.pipeline.set_state(gst.STATE_PLAYING)
                 return True

player = AudioPlayer()
loop = gobject.MainLoop()
gobject.threads_init()
context = loop.get_context()

while 1:
         value = sys.stdin.readline()
         if value == "next\n":
                 player.next()
         context.iteration(True)

Answer 1

In next you are setting the wrong thing to NULL:
self.filesrc.set_state(gst.STATE_NULL)

should be
self.pipeline.set_state(gst.STATE_NULL)

That is the crux of your problem, you aren't stopping the pipeline but also you do not need to unlink and relink self.convert either but that is a side issue.