AVPlayerLayer goes blank after several presentModalView/dismissModalView calls - iphone

Question

I have a video playing app which displays nothing in the AVPlayerLayer after repeatedly presenting and hiding the modal view which contains it. If I dismiss the modal view when this happens, the next load usually displays fine (?!!). The black screen issue happens roughly 20% of the time.
I build an AVMutableComposition to make the AVPlayerItem, but this bug happens even if there's only a single sample involved.
The issue can also be reproduced with a lot of app switching and turning music on and off. I do include music controls in my app (along with a simple view which displays the currently playing iTunes track).
This only happens on iOS 4. It used to happen on iOS 5 as well, but when I started recycling the view which contains the AVPlayerLayer, it worked fine. The only things I don't recycle are the AVPlayer and the relevant AVPlayerItem.
Here's how I load the assets and build a player:
- (void)loadAssetsFromFiles:(id)sender {
NSLog(#"loadAssetsFromFiles called");
assert ([assetURL2clipID count] > 0);
self.isWaitingToLoadAssets = NO;
composition = [AVMutableComposition new];
videoComposition = [AVMutableVideoComposition new];
[self releaseAssets];
//We're going to add this asset to a composition, so we'll need to have random access available
//WARNING: This can cause slow initial loading, so consider loading files later and as needed.
NSDictionary *assetOptions = [NSDictionary dictionaryWithObject:[NSNumber numberWithBool:YES]
forKey:AVURLAssetPreferPreciseDurationAndTimingKey];
//iterate through the asset urls we know we need to load
for (NSURL *fileURL in [assetURL2clipID allKeys])
{
AVURLAsset *asset = [AVURLAsset URLAssetWithURL:fileURL options:assetOptions];
assert(asset);
//index assets by clipID
[assets setObject:asset forKey:[assetURL2clipID objectForKey:fileURL]];
NSString *tracksKey = #"tracks";
[asset loadValuesAsynchronouslyForKeys:[NSArray arrayWithObject:tracksKey] completionHandler:
^{
NSLog(#"an asset completed loading values for keys.");
NSLog(#"Tracks loaded:");
[asset.tracks enumerateObjectsUsingBlock:
^(AVAssetTrack *obj, NSUInteger index, BOOL *stop)
{
NSLog(#"\n mediaType: %#\n trackID: %d\n", obj.mediaType, obj.trackID);
}];
NSArray *metadata = [asset commonMetadata];
for ( AVMetadataItem* item in metadata ) {
NSString *key = [item commonKey];
NSString *value = [item stringValue];
NSLog(#" metadata key = %#, value = %#", key, value);
}
if (!viewIsActive)
{
NSLog(#"An asset finished loading while the player view was inactive! Did you make sure cancelLoading called on this asset?");
}
// Completion handler block.
NSError *error = nil;
AVKeyValueStatus status = [asset statusOfValueForKey:tracksKey error:&error];
if (status == AVKeyValueStatusLoaded && error == nil) {
//if we've loaded all of our assets, it's time to build the composition and prepare the player!
loadedAssets++;
if (loadedAssets == [assets count])
{
CGSize videoSize = [asset naturalSize];
//every video composition needs these set
videoComposition.renderSize = videoSize;
videoComposition.frameDuration = CMTimeMake(1, 30); // 30 fps. TODO: Set this to the framerate of one of the assets
//using the assets we've already got
[self buildCompositions];
self.playerItem = [AVPlayerItem playerItemWithAsset:composition];
self.playerItem.videoComposition = videoComposition;
//TODO: Adding observer stuff should be on the main thread to prevent a partial notification from happening
[playerItem addObserver:self forKeyPath:#"status"
options:0 context:&ItemStatusContext];
[[NSNotificationCenter defaultCenter] addObserver:self
selector:#selector(playerItemDidReachEnd:)
name:AVPlayerItemDidPlayToEndTimeNotification
object:playerItem];
self.player = [AVPlayer playerWithPlayerItem:playerItem];
[playerView setPlayer:player];
[self.player addObserver:self forKeyPath:#"status" options:NSKeyValueObservingOptionNew context:nil];
self.isObservingPlayerStatus = YES;
}
} else if (error != nil) {
// Deal with the error appropriately.
NSLog(#"WARNING: An asset's tracks were not loaded, so the composition cannot be completed. Error:\n%#\nstatus of asset: %d", [error localizedDescription], status);
}
else
{
//There was no error but we don't know what the problem was.
NSLog(#"WARNING: An asset's tracks were not loaded, so the composition cannot be completed. No error was reported.\nstatus of asset: %d", status);
}
}];
}
}
That [self buildCompositions] function you see builds an AVVideoComposition to do opacity ramps, but I tried bypassing it and get the same problem.
When profiling the program, CoreAnimation reports a framerate of ~45 FPS when everything is working correctly, and 0-4 FPS when the blank screen rears its presumably ugly head.
This guy seems to have had a similar problem, but for me recycling the views really only fixed things for iOS 5:
Playing many different videos on iphone using AVPlayer