iOS stream playback with AVPlayer don't work - ios

Question

I play video streams with AVPlayer.
Some of streams plays only if click button "Play" for 2-5 times. (sorry, I can't provide link, and don't sure what especial in this streams, but may be problem only with full hd streams)
I do like that:
fields:
AVPlayerItem *playerItem;
AVPlayer *player;
AVPlayerViewController *playerViewController;
in viewDidLoad:
player = [[AVPlayer alloc] init];
playerViewController = [[AVPlayerViewController alloc] init];
playerViewController.player = player;
when click "Play":
NSURL *videoURL = [NSURL URLWithString:strUrl];
AVURLAsset *asset = [AVURLAsset URLAssetWithURL:videoURL options:nil];
playerItem = [AVPlayerItem playerItemWithAsset:asset];
[playerItem addObserver:self
forKeyPath:#"status"
options: NSKeyValueObservingOptionInitial | NSKeyValueObservingOptionNew
context:nil];
[player replaceCurrentItemWithPlayerItem:playerItem];
and observing:
NSLog(#"status changed");
if (((AVPlayerItem *)object).status == AVPlayerStatusReadyToPlay)
{
NSLog(#"ready to play");
[playerItem removeObserver:self forKeyPath:#"status"];
[self presentViewController:playerViewController animated:YES completion:nil];
[player play];
}
else if (((AVPlayerItem *)object).status == AVPlayerStatusFailed)
{
NSLog(#"failed to ready");
}
else if (((AVPlayerItem *)object).status == AVPlayerStatusUnknown)
{
NSLog(#"unknown");
}
First always "unknown" but in problem cases no messages after (but most streams play normally and I see "ready to play" message)
I've tried to observe player.status but when it ReadyToPlay and I start play I see only first frame and endless message "Loading" in top of screen.