AVPlayerItem fails with AVStatusFailed and error code "Cannot Decode"

Ok everyone, I have the answer to this straight from Apple. I used one of my developer TSI lifelines to ask the question, and I'll summarize the response.

There is a limit on the number of concurrent video players that AVFoundation will allow. It is due to the limitations of iOS hardware. The limit for current devices is 4 players. If you create a 5th player, you will get the "cannot decode" error. It is not a limit on the number of instances of AVPlayer, or AVPlayerItem. Rather,it is the association of AVPlayerItem with an AVPlayer which creates a "render pipeline", and you are limited to 4 of these. For example, this causes a new render pipeline:

AVPlayer *player = [AVPlayer playerWithPlayerItem:somePlayerItem];  // assuming the AVPlayerItem is ready to go with an AVAsset that has been loaded

I was also warned that you cannot assume that you will have 4 pipelines available to you. Another App may be using one or more. Indeed, I have seen this happen on an iPad, but it was not clear which app was using a pipeline.

So, there you go, it was totally undocumented, but that is the story.

I ran into the same error message after creating 4 AVPlayer instances, the fix in my case wasn't exactly the same though. Perhaps this will help anyone else who comes across this problem.

What I eventually found is that the AVPlayers were not being released when I had thought they were. In my case I was pushing my AVPlayer View Controller onto a Navigation Controller. Even though I was only creating one AVPlayer instance at a time, when the View Controllers are popped off a nav controller they were not being released immediately. It was then very easy for me to reach 4 AVPlayer instances before the old View Controllers were cleaned up.

It wasn't until I made sure that the previous players were released that this problem went away. To be complete I released the AVPlayerItem, AVPlayer and set the player on the AVPlayerLayer to nil before releasing.

I have to wonder if there is some limit on AVPlayer instances, unintentional or not. A related bit of info from the docs:https://developer.apple.com/library/ios/#documentation/AudioVideo/Conceptual/AVFoundationPG/Articles/02_Playback.html

"Multiple player layers: You can create arbitrarily many AVPlayerLayer objects from a single AVPlayer instance, but only the most-recently-created such layer will display any video content on-screen."

This one was absolutely killing me until I figured it out, picking up clues from this thread and a few others. The biggest single problem in my code was that I was instantiating my video player controller every time I wanted to play a video. Now, it gets instantiated once in the primary controller (in this case, my DetailViewContoller):

@interface DetailViewController () {    VideoPlayerViewController *videoPlayerViewController;}- (void) viewDidLoad{    [super viewDidLoad];    videoPlayerViewController = [[VideoPlayerViewController alloc] initWithNibName: nil bundle: nil];}

When I want to show a video, I call my DetailViewController's startVideoPlayback method:

- (void) startVideoPlayback: (NSString *)videoUID{    videoPlayerViewController.videoUID = videoUID;    [self presentModalViewController: videoPlayerViewController animated: YES];}

(NOTE: I'm passing it 'videoUID' -- a unique identified that was used to create the video in another part of the app.)

In the VideoPlayerViewController (which is largely cribbed from Apple's AVPlayerDemo sample), the one-time screen setup (initializing the AVPlayer, setting up the toolbar, etc.) is done in viewDidLoad -- which now only get's called once, and all per-video setup gets done within viewWillAppear, which then calls prepareToPlay:

- (void) prepareToPlay{    [self initScrubberTimer];       [self syncPlayPauseButtons];    [self syncScrubber];    NSString *documentsDirectory = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0];    //*** Retrieve and play video at associated with this videoUID    NSString *destinationPath = [documentsDirectory stringByAppendingFormat: @"/%@.mov", videoUID];    if ([self fileExists: destinationPath]) {        //*** Show the activity indicator spinny thing        [pleaseWait startAnimating];        [self setURL: [NSURL fileURLWithPath: destinationPath]];        //*** Get things going with the first video in this session        if (isFirst) {            isFirst = NO;        //*** Subseqeunt videos replace the first one        } else {            [self.mPlayer replaceCurrentItemWithPlayerItem: [AVPlayerItem playerItemWithURL: [NSURL fileURLWithPath: destinationPath]]];        }    }}