QTKit: QTMovieTimeDidChangeNotification

• Christian Schneider QTKit: QTMovieTimeDidChangeNotification May 11 2005, 14:08
  Hi all,
  
  can anybody tell me, when QTMovieTimeDidChangeNotification is fired? I
  was hoping it will be posted, when the timecode of a movie is changed,
  that is as a new frame is being displayed but that doesn't seem to be
  the case.
  
  Is there another way (*except using the callback mechanism in the
  standard quicktime controller*) to be notified of a movie's progress?
  Also, I'd prefer not to use an NSTimer as that will fire even when the
  movie's not playing.
  
  The reason for my asking is that I need to display the movie's current
  time (plus a certain offset) in a text field.
  
  Thanks
  
  chris
• Marco Scheurer Re: QTKit: QTMovieTimeDidChangeNotification May 11 2005, 20:58
  > can anybody tell me, when QTMovieTimeDidChangeNotification is fired? I
  > was hoping it will be posted, when the timecode of a movie is changed,
  > that is as a new frame is being displayed but that doesn't seem to be
  > the case.
  

  
  As a rule of thumb: not when you would expect. For instance if you
  have a movie, a selection, "plays selection only" and you play the
  notification will be sent *before* any frame is displayed. If you ask
  the movie for its current time upon receiving the notification you'll
  see that it has not changed! Seems pretty useless as it is now, if
  we're not mistaken.
  
  

  > Is there another way (*except using the callback mechanism in the
  > standard quicktime controller*) to be notified of a movie's progress?
  > Also, I'd prefer not to use an NSTimer as that will fire even when the
  > movie's not playing.
  

  
  We ended up using a Timer. You can always start and stop your timer.
  
  marco
  
  Marco Scheurer
  Sen:te, Lausanne, Switzerland  http://www.sente.ch
• Christian Schneider Re: QTKit: QTMovieTimeDidChangeNotification May 11 2005, 21:14
  Marco,
  
  thanks for your answer.
  
  I reverted to using the callback mechanism in QT's movie controller
  which actually is pretty straight forward. If anybody's interested in
  the code, mail me.
  
  chris
  
  On 5/11/05, Marco Scheurer <marco...> wrote:
  

  >> can anybody tell me, when QTMovieTimeDidChangeNotification is fired? I
  >> was hoping it will be posted, when the timecode of a movie is changed,
  >> that is as a new frame is being displayed but that doesn't seem to be
  >> the case.
  >
  > As a rule of thumb: not when you would expect. For instance if you
  > have a movie, a selection, "plays selection only" and you play the
  > notification will be sent *before* any frame is displayed. If you ask
  > the movie for its current time upon receiving the notification you'll
  > see that it has not changed! Seems pretty useless as it is now, if
  > we're not mistaken.
  >
  >> Is there another way (*except using the callback mechanism in the
  >> standard quicktime controller*) to be notified of a movie's progress?
  >> Also, I'd prefer not to use an NSTimer as that will fire even when the
  >> movie's not playing.
  >
  > We ended up using a Timer. You can always start and stop your timer.
  >
  > marco
  >
  >
  > Marco Scheurer
  > Sen:te, Lausanne, Switzerland  http://www.sente.ch
  >
  >
  
• Tim Monroe Re: QTKit: QTMovieTimeDidChangeNotification May 16 2005, 03:51
  On May 11, 2005, at 10:25 AM, Christian Schneider wrote:
  
  

  > can anybody tell me, when QTMovieTimeDidChangeNotification is fired? I
  > was hoping it will be posted, when the timecode of a movie is changed,
  > that is as a new frame is being displayed but that doesn't seem to be
  > the case.
  >
  > Is there another way (*except using the callback mechanism in the
  > standard quicktime controller*) to be notified of a movie's progress?
  > Also, I'd prefer not to use an NSTimer as that will fire even when the
  > movie's not playing.
  >
  > The reason for my asking is that I need to display the movie's current
  > time (plus a certain offset) in a text field.
  

  
  Sorry to take so long to answer this; the
  QTMovieTimeDidChangeNotification is fired whenever the movie time
  changes to a time ***other than what it would be during normal
  playback***. So it's not fired every frame. Some examples are: the user
  clicks in the movie controller bar to change the movie time, or a wired
  action changes the movie time.
  
  I think an NSTimer is the solution you are looking for.
  
  I'll make sure the documentation is updated to reflect this more
  refined notion of time-did-change.
  
  HTH,
  
  Tim Monroe
  QuickTime Engineering
  <monroe...>
• Christian Schneider Re: QTKit: QTMovieTimeDidChangeNotification May 17 2005, 10:47
  On 5/16/05, Tim Monroe <timmon...> wrote:
  

  >
  > On May 11, 2005, at 10:25 AM, Christian Schneider wrote:
  >
  >>
  >> The reason for my asking is that I need to display the movie's current
  >> time (plus a certain offset) in a text field.
  >
  > Sorry to take so long to answer this; the
  > QTMovieTimeDidChangeNotification is fired whenever the movie time
  > changes to a time ***other than what it would be during normal
  > playback***. So it's not fired every frame. Some examples are: the user
  > clicks in the movie controller bar to change the movie time, or a wired
  > action changes the movie time.
  >
  

  
  Thanks for clearing that up.
  
  

  > I think an NSTimer is the solution you are looking for.
  >
  

  
  Really? I am quite happy with the movie controller's callbacks. Is
  there any reason not to use those?
  
  chris