AVPlayerItem preload?

[deseven]

Hi, I've been playing with AVQueuePlayer a bit. It uses AVPlayerItem in order to queue items for playback, however it doesn't load added items immediately and waits until the last possible moment. Not only it adds a bit of a lag before it starts playing the next item, you are also not able to get the item information (like audio duration), which kinda ruins the purpose.

Here's an example:

Code: Select all

EnableExplicit

ImportC "-framework AVKit" : EndImport

; taken from https://www.purebasic.fr/english/viewtopic.php?p=544211#p544211
Structure CMTime
  value.q
  timeScale.l
  flags.l
  CMTimeEpoch.q
EndStructure

Define status,duration.CMTime
Define player = CocoaMessage(0, 0, "AVQueuePlayer new")
Define url = CocoaMessage(0,0,"NSURL fileURLWithPath:$",@"/path/to/file.mp3")
Define playerItem = CocoaMessage(0,0,"AVPlayerItem playerItemWithURL:",url)

CocoaMessage(0,player,"insertItem:",playerItem,"afterItem:",0)

; waiting doesn't do anything
;Delay(1000)

; here the status will always be 0 since the item is not yet loaded
status = CocoaMessage(0,playerItem,"status")
CocoaMessage(@duration,playerItem,"duration")
MessageRequester("test","press ok to play, current item status is " + Str(status) + ", duration is " + Str(duration\value))

CocoaMessage(0,player,"play")
Delay(1000)

; here the status should be 1 since we started playing and gave it some time to load, we also can get a duration now
status = CocoaMessage(0,playerItem,"status")
CocoaMessage(@duration,playerItem,"duration")
MessageRequester("test","started playing, current item status is " + Str(status) + ", duration is " + Str(duration\value / duration\timeScale))

So ideally you need to load the player item before the actual playback and the documentation actually says the following:

If you require inspecting an asset before you enqueue it for playback, call its load(_:) method to retrieve the values of one or more properties. Alternatively, you can tell the player item to automatically load the required properties by passing them to its init(asset:automaticallyLoadedAssetKeys:) initializer.

I tired looking into it, but it's all asynchronous and I have no idea about how to use such things in PB. Could anyone please help? Is it even possible?