Weird behaviour of AVPlayer

Question

I am merging multiple videos and playing it in AVPlayer. Video starts fine, but after sometime video freezes and only audio plays. I have a UISlider which helps to go forward or backward in video using seekToTime:.

So the weird part is that after video freezes, if I use the slider to go forward or backward, video starts playing perfectly fine. I have tried my app in multiple devices.

So basically I have to use seekToTime: method to give the video a nudge every time it freezes.

My code for merging video and playing back is following:

AVAsset *asset0 = [self currentAsset:0];
AVAsset *asset1 = [self currentAsset:1];
AVAsset *asset2 = [self currentAsset:2];
AVAsset *asset3 = [self currentAsset:3];
AVAsset *asset4 = [self currentAsset:4];

NSArray *assets = @[asset0, asset1, asset2, asset3, asset4];

AVMutableComposition *mutableComposition = [AVMutableComposition composition];
AVMutableCompositionTrack *videoCompositionTrack = [mutableComposition addMutableTrackWithMediaType:AVMediaTypeVideo
                                                                                   preferredTrackID:kCMPersistentTrackID_Invalid];
AVMutableCompositionTrack *audioCompositionTrack = [mutableComposition addMutableTrackWithMediaType:AVMediaTypeAudio
                                                                                   preferredTrackID:kCMPersistentTrackID_Invalid];

NSMutableArray *instructions = [NSMutableArray new];
CGSize size = CGSizeZero;

CMTime time = kCMTimeZero;
for (AVAsset *asset in assets)
{
    AVAssetTrack *assetTrack = [asset tracksWithMediaType:AVMediaTypeVideo].firstObject;
    AVAssetTrack *audioAssetTrack = [asset tracksWithMediaType:AVMediaTypeAudio].firstObject;

    NSError *error;
    [videoCompositionTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, assetTrack.timeRange.duration)
                                   ofTrack:assetTrack
                                    atTime:time
                                     error:&error];
    if (error) {
        NSLog(@"Error - %@", error.debugDescription);
    }

    [audioCompositionTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, assetTrack.timeRange.duration)
                                   ofTrack:audioAssetTrack
                                    atTime:time
                                     error:&error];
    if (error) {
        NSLog(@"Error - %@", error.debugDescription);
    }

    AVMutableVideoCompositionInstruction *videoCompositionInstruction = [AVMutableVideoCompositionInstruction videoCompositionInstruction];
    videoCompositionInstruction.timeRange = CMTimeRangeMake(time, assetTrack.timeRange.duration);
    videoCompositionInstruction.layerInstructions = @[[AVMutableVideoCompositionLayerInstruction videoCompositionLayerInstructionWithAssetTrack:videoCompositionTrack]];
    [instructions addObject:videoCompositionInstruction];

    time = CMTimeAdd(time, assetTrack.timeRange.duration);

    if (CGSizeEqualToSize(size, CGSizeZero)) {
        size = assetTrack.naturalSize;;
    }
}

AVMutableVideoComposition *mutableVideoComposition = [AVMutableVideoComposition videoComposition];
mutableVideoComposition.instructions = instructions;

mutableVideoComposition.frameDuration = CMTimeMake(1, 30);
mutableVideoComposition.renderSize = size;

pi = [AVPlayerItem playerItemWithAsset:mutableComposition];
pi.videoComposition = mutableVideoComposition;

player = [AVPlayer playerWithPlayerItem:[[CameraEngine engine] pi]];

player.volume = 0.75;
playerLayer = [AVPlayerLayer playerLayerWithPlayer: player];

playerLayer.frame = self.bounds;
[self.layer addSublayer: playerLayer];
[playerLayer setNeedsDisplay];
[player play];

UPDATE : Found out this link which describes similar problem. But his solution is not well understood.

"But his solution is not well understood." What do you mean by that? It seems clear enough. Do you mean _you_ don't understand it? — matt, Apr 03 '15 at 18:48
Also, can you explain what you are doing with AVMutableVideoCompositionInstruction? — matt, Apr 03 '15 at 18:50
Can you please comment the videoCompositionInstruction in your code and try the same. may be there is something wrong with that — Nitheesh George, Apr 03 '15 at 19:00

Nikita Arkhipov · Answer 1 · 2015-04-03T18:43:41.287

Why do you call [AVPlayer playerWithPlayerItem:[[CameraEngine engine] pi]] instead of [AVPlayer playerWithPlayerItem:pi]? Your construct your composition and assign it to pi while it is not used anywhere. Try to use [AVPlayer playerWithPlayerItem:pi] instead.

If this will not help try to change your videoComposition generation. Try to do the following:

AVMutableVideoCompositionInstruction *videoCompositionInstruction = [AVMutableVideoCompositionInstruction videoCompositionInstruction];
videoCompositionInstruction.timeRange = CMTimeRangeMake(kCMTimeZero, mutableComposition.timeRange.duration);
videoCompositionInstruction.layerInstructions = @[[AVMutableVideoCompositionLayerInstruction videoCompositionLayerInstructionWithAssetTrack:[mutableComposition tracksWithMediaType:AVMediaTypeVideo].firstObject]];

AVMutableVideoComposition *mutableVideoComposition = [AVMutableVideoComposition videoComposition];
mutableVideoComposition.instructions = @[videoCompositionInstruction];

mutableVideoComposition.frameDuration = CMTimeMake(1, 30);
mutableVideoComposition.renderSize = size;

after your for loop. Hope this helps!

Weird behaviour of AVPlayer

1 Answers1