Why would the FLVPlayback class throw a null reference exception from an internal method originating from a timer event?
As far as I can tell, this code path is not originating from within any of my code, so I cannot even determine why it is happening or what is causing it. Here is the stack trace in FlashDevelop:
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The annoying part is, there's nothing that can be done to prevent the error, since it's occurring in a timer event in a close-source component (FLVPlayback).
The error shouldn't be occurring at all, so my only workaround is to perform a fuzzy match for this particular error on its stack trace in my UncaughtErrorEvent handler: see comment starting with "Fuzzy identification of a particular error/bug..."
I am using FlashDevelop and Flash Professional.
In my original post, you can see the stack trace originates in an internal event registered by the fl.video.VideoPlayer component that calls it's own finishAutoResize and setState (to stopped) methods, which it turn fires and event that is handled by FLVPlayback.internal::handleVideoEvent method, which throws a null reference exception. I have no control over that code and no access to it. Even with FlashDevelop displaying all private/protected variables (the default), there was no source code to inspect.
I wasn't doing anything but using the FLVPlayback component. I loaded a file, registered some listeners, and tried to close the player when the FLV file finished downloading. There were no errors in my own code, but simply closing the FLVPlayback component via its closeVideoPlayer method is causing some kind of error, because in the meantime the VideoPlayer has a timer scheduled to run, which obviously ends up running code in the FLVPlayback component that just closed the video player. The error is definitely occurring in FLVPlayback.internal::handleVideoEvent, and it's probably occurring because, as kglad suggested, the closeVideoPlayer method is removing the video player from the stage, then trying to handle an event after the fact. FLVPlayback should detach all its listeners before it starts deconstructing the VideoPlayer in a way that's going to cause an intermittent time-sensitive error like this.
Here is the thread, stack, and local variables windows in FlashDevelop, along with a note explaining the stack position and the problem:
The code I settled on for closing the player is as follows. It stops the player, closes the underlying VideoPlayer (probably stops timers, etc.), clears the source property of the FLVPlayback component, and finally calls the closeVideoPlayer method to remove the video player. With this code, I haven't been able to reproduce the error, but I really should be able to just call closeVideoPlayer.
public static function closeActiveVideoPlayer( flvPlayer:FLVPlayback ):void
{
if (flvPlayer != null)
{
var activeIndex:uint = flvPlayer.activeVideoPlayerIndex;
try {flvPlayer.stop();} catch (e:Error){} //stop playback
try {flvPlayer.getVideoPlayer( activeIndex ).close();} catch (e2:Error){} //close internal VideoPlayer
try {flvPlayer.source = null;}catch(e3:Error){} //clear the source property
flvPlayer.closeVideoPlayer( activeIndex ); //use the recommended close method
}
}
I updated FLVPlayback.as, so instead of having just a createVideoPlayer method and a closeVideoPlayer method that fails to unwire events...
I've created two clear methods for wiring and unwiring the event listeners.
I've created two clear methods for registering and unregistering a video player.
I've created a separate method to configure/reconfigure a new or existing player.
So now, calling "createVideoPlayer" will create a video player, configure it, save references to it, and wire events.
Meanwhile, calling "closeVideoPlayer" will close/shutdown the video player, unwire events, and finally destroy all references to it last.
Here's what it should look like:
As for the Timer issue, I've filed a bug report, since it's very intermittent and is probably a low-level or platform-specific issue with how Timer events are queued and dispatched. It's hard to reproduce the issue, but it absolutely happens; the stack trace in my original post proves the event is originating at the Timer/tick, and the error confirms that closeVideoPlayer ran beforehand, meaning all timers were already stopped. Timer events should never, ever run after Timer.reset is called within ActionScript.
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