AVPlayer freezes when seeking between 2 videos

Does playback transition from one video to the next as expected if you just let it play (instead of seeking around)?

Code Block 
<AVMutableComposition: 0x2819a4000 tracks = (
    "<AVMutableCompositionTrack: 0x28195a540 trackID = 1, mediaType = vide, editCount = 2>",
    "<AVMutableCompositionTrack: 0x281960c40 trackID = 2, mediaType = soun, editCount = 2>"
)>

Looks like this bug still persists in iOS 15 as well. I see this when I have three videos with transition between first two. The returned frame on seek is incorrect, the only way to reset the player to display current frame is by firing AVPlayer.play(). I wonder how such basic bugs persist even after 10 years of AVFoundation framework release!

Still got this issue. Pausing/playing video makes my preview not smooth.

Anyone found a solution to this. I am trying to merge two or more videos but the output has this issue. I have tried to find a solution but there seems to be little to no information regarding this specific... bug?

Hey! I just solved this problem and am very happy to share my working solution. The trick here is that two videos can have different fps. And we need to update the frameDuration AVMutableVideoComposition parameter of our AVPlayerItem

in general, the code looks like this

enum Const {
	static let perciseValue = 1000000
}

struct SemgentModel {
	let framerate: Float
	let timeRange: CMTimeRange
}

var mySegments: [SemgentModel] = ..add segments
var player: AVPlayer?

func updateFramerateOfComposition(newRate: Float) {
	let mutableComposition = player?.playerItem?.videoComposition?.mutableCopy() as? AVMutableVideoComposition
    mutableComposition?.frameDuration = CMTime(value: CMTimeValue(1 * Const.perciseValue), timescale: CMTimeScale(newRate * Float(Const.perciseValue)))
    player?.playerItem?.videoComposition = mutableComposition
}

func setTime(time: CMTime) {
	if let segment = mySegments.first(where: { $0.timeRange.contains(time) }) {
		updateFramerateOfComposition(newRate: segment.framerate)
	}
	player?.seek( to: seekTargetTime, toleranceBefore: .zero, toleranceAfter: .zero) { ... }
}

Hello! It turned out to solve this problem with a trick when creating an AVComposition. Namely, when creating AVComposition, I began to use two instead of one AVCompositionTrack in a checkerboard pattern. This solves the problem of not only different fps for neighboring videos, but also a different transform, if it was applied.

let videoTracks = [
    composition.addMutableTrack(withMediaType: .video, preferredTrackID: kCMPersistentTrackID_Invalid)!, 
    composition.addMutableTrack(withMediaType: .video, preferredTrackID: kCMPersistentTrackID_Invalid)!
]

let timeRangeStart: CMTime = .zero
for (index, asset) in assets.enumerated() {
    let videoTrack = videoTracks[index % 2]
    let assetTrack = asset.tracks(withMediaType: .video).first
    let timeRange = CMTimeRange(start: .zero, duration: asset.duration)
    do {
        try videoTrack.insertTimeRange(
            timeRange,
            of: assetTrack,
            at: timeRangeStart
         )
         timeRangeStart = timeRangeStart + timeRange.duration
    } catch {
        logError()
    }
}

Found another solution here which may be helpful as it doesn't require adding multiple tracks.

Simply call seek time twice, once without specifying tolerance, and then AFTER, with specifying a tolerance for frame by frame increments.

 let seekTime = CMTime(seconds: timeToSeekTo, preferredTimescale: yourPreferredTimescale)
            playerItem?.seek(to: seekTime) { [weak self] _ in // where player item is an AVPlayerItem created using your composition
                
            }
            playerItem?.seek(to: seekTime, toleranceBefore: .zero, toleranceAfter: .zero) { [weak self] _ in
            }

has this issue been resolved by Apple? We are faced with similar issue when seeking very slowly between two videos.