Note to (debugging) developers, especially PyQt developers using QSlider sigals

See Player_and_slider.py for full code.

When you try to put together the relationships of sliders and players, it is possible to call each other (make both of them interdependent), like this:

self.slider.sliderMoved.connect(self.set_pos)
self.slider.sliderPressed.connect(self.set_pos_smooth)
self.player.durationChanged.connect(self.update_dur)
self.player.positionChanged.connect(self.update_pos)  

And the corresponding (simplified) script goes like this:

def set_pos(self, pos):
    self.player.setPosition(pos)


def set_pos_smooth(self):
    self.player.setPosition(self.slider.value())


def update_pos(self, pos):
    self.slider.setValue(pos)


def update_dur(self, dur):
    self.slider.setRange(0, dur)                               

However, it is important to know that different slider signals varies, and have differnet influences on performace.

• sliderMoved->set_pos: Detects the movement of the slider, only triggered by changing playback position of player ( user's intentions does not work, as the slider bounces back). Passes the current position to script (pos).
• valueChanged: Detects the movement of the slider, triggered both by user and player. Passes the current position to script.
  Caution: this makes audio stuck and pop, even when played without user interfering, and might be regarded as buffer issue (which confused me for a while), but the actual cause is unsure.`
• sliderPressed->set_pos_smooth: An intermediate solution to fix the valueChanged issue. Only trigged by users, but does not pass the current position to script, a little tweak in the script set_pos_smooth is made.

In my code, only sliderMoved and sliderPressed are used, to avoid the issue above. The control of the slider between player and user is separate.